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RADIO ASTRONOMY

Journal of the Society of Amateur Radio Astronomers March- April 2015

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Radio Waves President’s Page 3 Editor’s Notes 4 News Mark Your Calendar 6 Call for Nominations 7 Officer and Director Nominations 8 SARA 2015 Voting Ballot 13 Agenda for Board of Directors Meeting June 22, 2015 14 Summary of 2015 SARA Western Conference 15 SARA Annual Conference at NRAO 19 2015 Annual Conference Keynote Speaker 19 SARA 2015 Conference Abstracts 19 Call for Papers: 2015 SARA Annual Conference 24 Feature Articles European Solar Eclipse Observed by Radio Waves- C. Monstein 24 Coronal Mass Ejection Effects on HF Radio Propagation--W. Reeve 29 Strong RFI Observed in the Protected Deuterium Band-C. Monstein 32 1.4 GHz radio telescope Part 1:- K. Kornstett 35 GPS Network Time Server on Raspberry Pi :GpsNtp—Pi; W. Reeve 51 The Cold Never Bothered Me Anyway—E. Siegel 63 Measuring the Milky Way angle (or how I got into radio astronomy)—K. Kornstett 65 Documentation—D. Typinski 74 Scientific Method—S. Olney 77 Reber’s Cosmology—D. Typinski 83 JJRO Observation Report—Julian Jove 85 Book Review—Radio Propagation-Principles and Practice 86 Book Review: The Hobbyist’s Guide to the RTL-SDR: Really Cheap Software Defined Radio 88 Membership New Members 91 SARA Membership Dues and Promotions 91 Administrative Officers, directors, and additional SARA contacts 94 Resources Great Projects to Get Started in Radio Astronomy 95 Education Links 97 Online Resources 98 For Sale, Trade, and Wanted SARA Polo Shirts 99 For sale 100

Ken Redcap SARA President Kathryn Hagen Editor Whitham D. Reeve Contributing Editor Christian Monstein Contributing Editor Stan Nelson Contributing Editor Lee Scheppmann Technical Editor Radio Astronomy is published bimonthly as the official journal of the Society of Amateur Radio Astronomers. Duplication of uncopyrighted material for educational purposes is permitted but credit shall be given to SARA and to the specific author. Copyrighted materials may not be copied without written permission from the copyright owner. Radio Astronomy is available for download only by SARA members from the SARA web site and may not be posted anywhere else. It is the mission of the Society of Amateur Radio Astronomers (SARA) to: Facilitate the flow of information pertinent to the field of Radio As-tronomy among our members; Promote members to mentor newcomers to our hobby and share the excitement of radio astronomy with other interested persons and organizations; Promote individual and multi station observing programs; Encourage programs that enhance the technical abilities of our members to monitor cosmic radio signals, as well as to share and analyze such signals; Encourage educational programs within SARA and educational outreach initiatives. Founded in 1981, the Society of Amateur Radio Astronomers, Inc. is a membership supported, non-profit [501(c) (3)], educational and scientific corporation. Copyright © 2014 by the Society of Amateur Radio Astronomers, Inc. All rights reserved. Photograph: National Radio Astronomy Observatory, Green Bank, West Virginia

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Radio Waves President’s Page The annual conference in West Virginia is fast approaching (June 21-24) and the deadline for early registration is May 31. After that date, an additional charge will be added to the US$165 fee. In addition to the knowledge shared by our accomplished presenters, attendees will receive snacks, eight meals, a printed copy of the proceedings and their 2016 SARA membership. Note that lodging is NOT included in this fee. Candidates for Treasurer, Secretary, Director and Director-at-Large have also submitted biographies for your consideration. The election will take place at the June conference. A sample ballot appears after the bio section. Our candidates' range of experiences and expertise makes fascinating reading so I hope you'll spend some time with this section. Our Radio Astronomy Journal submissions reflect this range as well. Thanks to all the authors who share the results of their investigations and evaluations with us. We also appreciate your patience as our editor gets accustomed to the way we do things. Last but not least is the Dayton (OH) Hamvention® from May 15-17. This is an excellent outreach activity for SARA, we get new members and we meet new people who are interested in SARA. But to make this all happen, we need volunteers to man the booth. Are you planning on coming to Dayton? Stop in for an hour or two, share your enthusiasm and help promote SARA! Hope to see you in West Virginia! Tom Hagen, Vice President

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Editor’s Notes We are always looking for basic radio astronomy articles, radio astronomy tutorials, theoretical articles, application and construction articles, news pertinent to radio astronomy, profiles and interviews with amateur and professional radio astronomers, book reviews, puzzles (including word challenges, riddles, and crossword puzzles), anecdotes, expository on “bad astronomy,” articles on radio astronomy observations, suggestions for reprint of articles from past journals, book reviews and other publications, and announcements of radio astronomy star parties, meetings, and outreach activities. If you would like to write an article for Radio Astronomy, please follow the Author’s Guide on the SARA web site: http://www.radio-astronomy.org/publicat/RA-JSARA_Author’s_ Guide.pdf. You can also open a template to write your article http://www.radio-astronomy.org/publicat/RA-JSARA_Article_Template.doc Let us know if you have questions; we are glad to assist authors with their articles and papers and will not hesitate to work with you. You may contact your editors any time via email here: editor@radio-astronomy.org. I will acknowledge that I have received your submission within two days. If I don’t, assume I didn’t receive it and please try again.

Please consider submitting your radio astronomy observations for publication: any object, any wavelength. Strip charts, spectrograms, magnetograms, meteor scatter records, space radar records, photographs; examples of radio frequency interference (RFI) are also welcome. Guidelines for submitting observations may be found here: http://www.radio-astronomy.org/publicat/RA-JSARA_Observation_Submission_Guide.pdf

Tentative Radio Astronomy due dates and distribution schedule

Issue Articles Radio Waves Review Distribution Jan – Feb February 12 February 20 February 23 February 28 Mar – Apr April 12 April 20 April 25 April 30 May – Jun June 12 June 20 June 25 June 30 Jul – Aug August 12 August 20 August 25 August 31 Sep – Oct October 12 October 20 October 25 October 31 Nov – Dec December 12 December 15 December 20 December 31

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News 2015 SARA Annual Conference to be Held June 21 to June 24

National Radio Astronomy Observatory, Green Bank, West Virginia, USA

Conference Registration Fees: The fee for the 2015 SARA Conference has been set at U$165 for all registered participants. This fee includes Conference registration, payment of your 2016 SARA membership dues, and one copy of the published Conference Proceedings (to be distributed at the meeting), morning coffee breaks, afternoon snack breaks, evening refreshments, and eight meals, as indicated below. Lodging is NOT included. Please note that all SARA 2015 memberships expire on 15 June 2015. Since SARA Membership Dues are now inseparable from Conference registration; all registered attendees automatically become SARA Members in Good Standing through 15 June 2016. SARA Life Members, or those who have already paid their 2016 membership dues prior to registering, may deduct $20 from the above amount. Those registered for the 2015 Conference who subsequently purchase a Life Membership anytime during the 2015~2016 membership year may deduct $20 from the Life Member Fee (currently set at US$400). And, because SARA offers a special membership rate of US$5.00 for students, all fulltime students under the age of 18 may deduct US$5.00 from the above Conference registration fee. The attendance fee for an accompanying family member (non-participating spouse, child, or companion of a registered Conference attendee) is US$80, which includes morning coffee breaks, afternoon snacks, evening refreshments, and meals. The cited fees are calculated on a break-even basis, and apply only to advance registrations received prior to 31 May 2015. All registrations received thereafter are subject to an additional late registration fee, as indicated below. Included Meal Plan: Green Bank is a small community with few dining establishments. Thus, SARA has arranged for conference registration to include a meal plan at the NRAO employee's cafeteria, to include:

• Dinner Sunday night • Breakfast / Lunch / Dinner Monday and Tuesday • Breakfast on Wednesday

The NRAO Cafeteria is not a public dining facility, does not sell individual meals to visitors, and is, in fact, doing us a favor in allowing our group to use their cafeteria at all. Thus, the Meal Plan is an integral part of, and inseparable from, Conference Registration. Please note that, in addition to the above meals, the Conference fee (or Accompanying Person fee) includes refreshments and coffee breaks during the Conference presentations, and snacks and beverages in the Drake Lounge in the evenings.

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Exceptions to the meal plan will be considered on a case-by-case basis, for those Conference attendees residing on site, or others with special dietary needs. Please contact our Treasurer directly with your specific requests. In general, except under unusual circumstances, one should consider the cost of meals to be a part of, and inseparable from, the conference registration fee. Conference Proceedings: Once again this year, a formal, printed Proceedings is being professionally published. One copy of the Proceedings is included in your paid Conference Registration. (Proceedings are not provided to accompanying family members.) A limited number of additional copies of this year's and previous years' Proceedings will be available at Green Bank for US$20 each. You may, if you wish, reserve and prepay additional Proceedings copies, by including the appropriate amount in your check to our Treasurer. Advance Registration Deadline: Because SARA Conferences require quite a bit of advance planning, early registration is encouraged. To register for the 2015 SARA Conference at the rates cited above, your remittance in full must be received by our Treasurer (not simply postmarked) not later than 31 May, 2015. All registrations received after that date, or walk-in registrations, will be assessed an additional 15% late registration fee. Payment of Conference Fees: Payment for the conference can be made by check, money order, PayPal or credit card. Complete the registration form at http://www.radio-astronomy.org/node/208 and submit with payment. Checks (in US Dollars only, drawn on a US bank) should be sent in advance to:

SARA 2189 Redwood Ave Washington, IA 52353 USA

You can also make payment by going to www.PayPal.com and send money to treasurer@radio-astronomy.org. Additional information concerning lodging, directions and information for first time attendees can be found at this link: http://www.radio-astronomy.org/?q=node/208 Mark Your Calendar May 6, 2015- Nobel Prize recipient Dr. Joseph Taylor, K1JT, will speak at Gloucester County Amateur Radio Club in Williamstown, NJ. The informal session starts at 19:00 and the formal meeting at 19:30. More information on the club can be seen at www.w2mmd.org. May 15-17, 2015 Hamvention Dayton, Ohio http://www.hamvention.org/index.php June 21-24, 2015 SARA Annual Conference at National Radio Astronomy Observatory in Green Bank, West Virginia www.radio-astronomy.org/q=node/208 Do you have an event to share with SARA members? Send information to editor@radio-astronomy.org to be included in the next issue.

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Call for Nominations As required by Section 3 of SARA By-Laws (see below), this is the official call for nominations for SARA officers and board members. If you are interested in running for office and would like to know more about the positions, please contact a board member or SARA President Ken Redcap (president@radio-astronomy.org). The requirement to be on the board is to attend the board meetings at the annual meeting and to actively participate in board-related activities. If you are unable to attend the annual meetings, then the director at large position may be for you. This position is a full board position except that attending the annual meeting is not required. The following positions will be up for election in June 2015: Secretary, Treasurer, two Director at Large and two regular Directors. If you would like to run for one of the available SARA officer or board positions please send a note to Secretary Bruce Randall (secretary@radio-astronomy.org) copying President Ken Redcap. Interested persons should review the duties and responsibilities by reading the Operating Procedures found at http://www.radio-astronomy.org/pdf/operating-procedures.pdf Contact information also is listed in the Administrative Info tab on the SARA website (www.radio-astronomy.org) and in the Administrative section of the SARA journal. Text from the By-Laws: SECTION 3: Elections of Directors and Officers will be accomplished by the President placing an initial call for nominations in "The Journal" no less than ninety (90) days prior to the regular scheduled meeting. Two (2) nominations from different members will be required to nominate a member for an office. No less than thirty (30) days prior to this meeting (in a newsletter issued prior to the meeting), the President will place a notice of the results of the nominations in "The Journal", along with a ballot for the members to use to vote for the nominee of their choice. This ballot will be forwarded to the Secretary for collection and counting at the regular meeting.

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Officer and Director Nominations Treasurer (Two One year term) Nominated for Treasurer- Gary Lynn Memory Born and raised in Springville, Utah and currently living in Purcellville, Virginia with his wife Carla. Has 18 years of overseas assignment experience Attended Brigham Young University and Graduated in Electronics Technology from Utah Technical College in 1982. FCC Radiotelephone with Radar Endorsement Certified by International Society of Certified Electronic Technicians (ISCET) ISCET and FCC license testing administrator Central Intelligence Agency, Retired Field Engineer, Instructor, Division Chief of Engineering, Base/Facility Director Currently employed by Harris Corporation as the USGOV Classified Sales Manager/Consultant Interests:

Ham Radio Extra Class, N7BRJ Private Pilot Ex-EMT Digital photography Astronomy, both radio and visual Pro audio support and recording Building computers from scratch Auto Mechanic NASA History Junkie Long distance running

As a young child I would tear apart new toys to find out how they worked (including a short wave radio that my parents owned). Later I worked for my father in his business as an auto mechanic. Among many other experiences, the process of learning how to tear apart, clean and then rebuild an automobile carburetor has been an unexpected foundation for my life. It led the way toward being able to understand all things from a mechanical perspective. I would later build my own radio and antenna gear. After college my family and I moved to Virginia in order to accept a position with the USGOV. My career required engineering and management of communication systems from “DC to Daylight”. I currently work as a Tactical Communications Consultant. My wife, Carla is also a Ham (N7EVN). We have four children, all of which have graduated from college and are currently pursuing their chosen professions.

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Secretary (Two One year term) Nominated for Secretary- Bruce Randall

Hello I’m Bruce Randall and live in Rock Hill S.C. I was born in 1949, so am getting to be an old timer. My first ham radio license was in 1966. Presently I have an extra class license with the call of NT4RT. (The RT in the call is for “Radio Telescope.”) Ham radio and optical astronomy led to my interest in radio astronomy. I Retired September 2013. I had been an electronic engineer since 1978, with involvement in analog circuit design, power supplies, electromagnetic compatibility, a bit of DSP work and some antenna design. My hobbies include old British cars, astronomy, ham radio and radio astronomy. I also enjoy canoeing, hiking and camping, as time permits. I have been a SARA member for over 20 years and am now a life member. Experiments with radio astronomy started in 1990, in the days of the chart recorder as the output device. The present interested is interferometers and possible extended baselines in the future. I have been on the SARA board in the past and would like to serve SARA as secretary.

Director-At-Large (Two year term) Two Open Positions Nominated for Director-At-Large: Stuart Rumley

Stuart has over thirty years experience in electrical engineering, optical engineering, and metrology engineering. As President and owner of Valon Technology LLC, his principal activity has been designing and developing RF and microwave products for a wide variety of clients.

Products designed include short-range radar transceivers, wireless video devices, RFID readers, high-dynamic range transceivers for WAN applications, wireless automatic meter reading equipment (Smart Meters), short-range transmitters and receivers for keyless entry and property location, and wide variety of RF and analog design projects including expert witness assignments.

Stuart has written many articles and holds several patents.

Prior to establishing Valon Technology, Stuart worked in the wireless technology industry as a hardware engineering manager and as a product design engineer.

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Director-At-Large (Two year term) Two Open Positions Nominated for Director-At-Large: Steve Berl I was born in 1958, the same year as NASA. I’ve always been very interested in space exploration, from the ground and in space, both human, and robotic. I studied Electrical Engineering at Tufts University, then on to get my Masters in Computer Science from UC San Diego. From there it was off to work at NBI in Boulder Colorado, and finally to the San Francisco bay area where I still live and have worked at a variety of companies such as Apple and Cisco Systems. Unfortunately none of those jobs had anything to do with exploring space. Upon retiring a few years ago, I decided to get into space exploration in a big way. I joined Team Phoenicia, one of the entrants in the Google Lunar X Prize competition to build and fly a robotic lander and rover to the moon. The team ran out of funding, and my interest moved to science education. I hope to get young people as excited about science and engineering as I was when I was young and men were flying to the moon. I became a volunteer at Chabot Space and Science Center in Oakland, CA. At Chabot, I am involved in many different activities, from operating our original 1883 8” Alvin Clarke telescope to being crew in the Challenger Learning Center where we take 5th graders on simulated missions to Mars. I’ve implemented both a SuperSID monitor and an Itty Bitty Radio Telescope there to help teach the public about how we study the sun.

I’m also a member of the East Bay Astronomical Society, which together with Chabot Space and Science Center operates the observatory, does outreach throughout the Bay Area. I have given presentations there about radio astronomy, and how to use it as a teaching tool. I also run the machine shop. Current projects include improvements to the SuperSID software to enable real-time display of SID data, an RTL-SDR based forward scatter meteor detection system, and getting my Callisto Solar Radio Spectrometer up and running. And here is a picture of me sitting in a real Soyuz spaceship.

Director Director-At-Large (Two year term) Two Open Positions Nominated for Director-At-Large: Jon Wallace Jon Wallace was an award-winning high school science teacher in Meriden, Connecticut for over 32 years. He is past president of the Connecticut Association of Physics Teachers and was an instructor in Wesleyan University’s Project ASTRO program. He has managed the Naugatuck Valley Community College observatory and run many astronomy classes and training sessions throughout Connecticut. Jon has had an interest in ‘non-visual’ astronomy for over thirty years and has built or purchased various receivers as well as building over 30

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demonstration devices for class use and public displays. He was on the Board of the Society of Amateur Radio Astronomers (SARA), is currently the Education Coordinator for SARA, and helped develop teaching materials for SARA and the NRAO (National Radio Astronomy Observatory) for use with their IBT (Itty-Bitty radio Telescope) educational project as well as beginner materials for the SARA website and journal. In addition, Jon wrote a series of four articles in 2009 and 2010 about radio astronomy for QEX magazine which are reprinted, with permission, on the SARA website. He is currently developing a video and support materials for a microwave antenna demonstration that he hopes to post on the SARA website soon. Other interests include collecting meteorites, raising arthropods (“bugs”) and insectivorous plants. Jon has a BS in Geology from the University of Connecticut; a Master's Degree in Environmental Education from Southern Connecticut State University and a Certificate of Advanced Study (Sixth Year) in Science (Astronomy) from Wesleyan University. Director (Two year term) Two Open Positions Nominated for Director: Dave Cohen

Dave Cohen has been interested in science since an early age. As a child, he was mainly inspired by scientist Carl Sagan and the Apollo Moon missions, both who started a lifelong interest in Astronomy. Scientific American's Amateur Scientist book provided a source of entertaining and dangerous experiments that kept his parents wondering when he might catch the house on fire. Dave later became involved in amateur radio astronomy, and has been a member of SARA since 2011. He currently has an operational Radio Jove, Super SID, and eight-foot homebrew stressed parabolic reflector, with a 1420 MHz SETI feed. He has attended Chattaqua short courses at both Green Bank, WV, and the VLA at Socorro, NM. Dave also mentored the construction

of a Radio Jove telescope at a local high school, and has organized student field trips to the SARA Eastern conference at Green Bank. He has been Flexicell's chief mentor for FIRST Robotics (For Inspiration and Recognition of Science and Technology) since 2006, a national program where youth are trained in the skills necessary to build robots to compete with other high schools across the country. Dave instructs students in 3D solid modeling, machining, and assembly. Dave has been employed as an electrical engineer in controls and automation since 1994, and in industrial robotics since 2004 at Flexicell, Inc. His primary task is the design of electrical controls for Fanuc and Kuka packaging/palletizing systems. He also works with college interns on research and development projects, one of which includes an Automatic Guided Vehicle to integrate with palletizing robots.

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Director (Two year term) Two Open Positions Nominated for Director: Tom Crowley

Tom Crowley's interest in radio astronomy dates back to 1987 when he joined the Society of Amateur Radio Astronomers (SARA). He has held various positions in that organization including president, vice-president, treasurer and director. Tom is a volunteer instructor at the National Radio Astronomy Observatory (NRAO) in Green Bank, West Virginia, teaching people how to use the 40-ft. educational radio telescope. Tom also heads the NRAO Navigator outreach program. Tom has been an optical amateur astronomer since 1985. He has discovered five supernovas, and he has served on the board of the Atlanta Astronomy Club. After a career in technical and executive management in computer manufacturing and international communication networks, Tom retired

in 2002. He and his wife Lynn live part of the year in Florida's Chiefland Astronomy Village. Both the CAV Fall Star Party in November and the CAV Spring Picnic in April are held on his property. Director (Two year term) Two Open Positions Nominated for Director: Charles Osborne Charles Osborne has held various positions from Director, VP, to President within SARA for many years. He was founder of the Southeastern VHF Society and has held Director and President position multiple terms there as well. Professionally Charles is an RF Systems Engineer working in the Antenna Range Instrumentation Product Development group at MITechnologies. Prior to that he held Sr Satcom Systems Engineering positions at DataPath and Rockwell Collins. He was Lead Engineer at AT&T Tridom. Division Manager of Test Engineering at Electromagnetic Sciences, and Manager of RF Engineering in the Satcom Division of Scientific Atlanta. For 8 years ('99~2007) he was on the Professional side of Radio Astronomy working as Technical Director of the Pisgah Astronomical Research Institute. There helping to convert a NASA/DOD surplus facility into a radio and optical astronomy remote lab for university students in North Carolina and surrounding states. Prior to that he was an advisor on radio astronomy and RF systems engineering to a student project for Georgia Tech renovating two surplus 100ft dishes in Woodbury Georgia. He also won county teacher of the Year for volunteer teaching science for K~3rd grade gifted students. He called it "Quantum Mechanics for Third Graders". Charles has a BSEE degree from NC State University specializing in RF and Antenna Engineering. His hobby interests are widely varied: radio ( 3.7m dish) and optical astronomy of course, amateur radio VHF/microwave design, metal working, art glass, long range target shooting, restoring vintage cars & motorcycles, gardening, model rockets, computers, RF test equipment, photography, oil and water color painting, flying, and when Janis lets him, he drives her red '67 Camaro convertible show car.

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SARA 2015 Voting Ballot

Treasurer: Vote for One (1)

___ Gary Memory

___ Write In _______________________________

Secretary: Vote for One (1)

___ Bruce Randall

___ Write In _______________________________

Director: Vote for Two (2)

___ Dave Cohen

___ Tom Crowley

___ Charles Osborne

___ Write In _______________________________

___ Write In _______________________________

Director at Large: Vote for Two (2)

___ Steve Berl

___ Stuart Rumley

___ Jon Wallace

___ Write In _______________________________

___ Write In _______________________________

___ Write In _______________________________

Members voting by e-mail should send their completed ballot to: secretary@radio-astronomy.org no later than June 22, 2015 11:00 PM EDST.

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Agenda for Board of Directors Meeting June 22, 2015

Reports from Officers President Vice-President Treasury Secretary Other Reports Grant Committee Education Outreach SuperSID program- Tom Hagen/ Keith Payea SARA Journal- Kathryn Hagen Old Business RASDR Update Website- Chip Sufitchi SARA Store SARA Sections- Stephen Tzikas New Business Annual Meeting location and time Western Conference location and time, March 2016, Embry-Riddle University, Prescott, AZ Volunteers needed for: Orlando Hamcation, February 12-14, 2016 USA Science & Engineering Festival, Washington, DC, April 16-17, 2016 Dayton Hamvention, May 20-22, 2016 Astronomy on the Lawn, Washington, DC, June 2016

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Summary of 2015 SARA Western Conference Stanford, California Julian Jove The 2015 SARA Western Conference was held on Stanford University campus in Palo Alto, California USA over the weekend of 20~22 March. David Westman, Keith Payea, Lorraine Rumley, and of course Bill and Melinda Lord with the onsite help of Debbie and Phillip Scherrer again worked hard to get everything set up. We had 40± attendees and speakers at this year’s conference and to my knowledge there were no trouble-makers in the group except our new president, Ken Redcap, who was elected and replaced our previous resident trouble-maker and past president Bill Lord. The format for this conference included presentations by SARA members and outside speakers and a tour of the Stanford Linear Accelerator Center (SLAC) and Kavli Institute for Particle Astrophysics and Cosmology (KIPAC) facility on the Stanford campus.

Dave Westman opened the conference and was followed by a welcome from Philip Scherrer, Research Professor in the Department of Physics at Stanford University. Ken Redcap, SARA president, then oversaw introductions of all attendees and made the first presentation: 611 MHz Total Power Radio Telescope. This was a continuation of Ken’s presentations at previous SARA conferences. In this one he described several software defined radio (SDR) receivers and accessories that may be used in amateur radio astronomy including the HackRF One, AirSpy, NooElec and the Ham-It-Up up-converter. The cost of the devices described ranges from around 15 USD to 200 USD. The NooElec SDR represents the bottom in

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cost and performance with the more expensive units generally providing higher performance in terms of continuous frequency range and RF and IF filtering and frequency stability. Next, the inimitable SARA director Curt Kinghorn presented Amateur Radio Astronomy Overview on the cheap. In particular, he described a system that receives in the band allocated to unused TV channel 37 (608 to 614 MHz). The system he described required an investment less than 500 USD. It uses an array of off-the-shelf television antennas, CATV preamplifier, a used general coverage receiver (Icom R7000), laptop soundcard, and Radio-SkyPipe software. Curt was inspired by a presentation made at the 2010 SARA Western Conference, in which a presenter suggested the viability of using channel 37 for amateur radio astronomy. Curt described, in a machinegun cadence, making 611 MHz radio sky maps from Radio-SkyPipe drift-scan data. After collection the data is imported into Excel. Conditional cell formatting of the data provides a coarse sky map in the spreadsheet. The data also can be imported into Stellarium (a free planetarium program) as an overlay on an optical sky map. To quote Curt, making radio sky maps in this fashion is “honkin’ big stuff” and we believe him. Dean Knight followed Curt with a presentation on Student’s Hands-On Introduction to Radio and Radio Astronomy at Sonoma Valley High School, which included descriptions of the Sonoma Valley High Engineering Academy, Sonoma Valley Electronics Club and Valley of the Moon Amateur Radio Club (VOMARC). Dean demonstrated several electronics projects that can be built cheaply, simply and easily. SARA vice president Tom Hagen’s presentation VLF Receiver for Making Calibrated Magnetic Field Strength Measurements was a follow-up of his presentation at the 2014 SARA Western Conference at Bishop, California. He described construction of the receiver preamplifier using an instrumentation amplifier and construction methods for a balanced (center-tapped) loop antenna. Tom uses a Syba soundcard for his tests and measurements and he discussed alternative preamplifiers using a grounded (unbalanced) loop, relevant loop equations, noise analysis and measurements. Tom and Ken Redcap later setup the system for demonstration outside between the Varian and the Physics and Astrophysics buildings. The number of VLF stations received and processed by SpectrumLab software was astounding considering the high RF noise level at this location. Later, we learned about the “Hagen Effect”, which states “If the velocity is constant, the first derivative is zero.” Thanks, Tom! Ray Fobes came over from Prescott, Arizona, where he runs the radio astronomy facilities at Embry-Riddle University, to describe their Dipole Array Radio Telescope. The DART is patterned after the Murchison Widefield Array Low Frequency Demonstrator (MWA LFD). Ray’s system uses a 3-tile array, each with 16 crossed-dipole antennas at a total cost of around 30 thousand USD. Ray acknowledges this is cost prohibitive for most amateur radio astronomers. Ray hopes to have the system ready for the next SARA Western Conference

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planned at Prescott in 2016. Next, Paul Shuch delivered his presentation on Electromagnetic Spectrum Basics, which covered the entire electromagnetic spectrum from dc to gamma rays, the terminology used to describe wavelength and frequency and their relationship to the speed of propagation. Whitham Reeve followed Paul with Sudden Frequency Deviations Caused by Solar Flares, a 6-month study he undertook from June to December 2014 using WWV and WWVH time signals on 15 and 20 MHz. Sudden frequency deviations result from perturbations in Earth’s ionosphere when energetic particles ejected by a solar flare impact Earth’s atmosphere causing Doppler shifts in the time signals. Time was allocated at the conference for short impromptu discussions and presentations, called Open Mic. This year we saw Scotty Butler’s picture tour of antennas she has photographed around the world, Glenn Worstell talked about software defined radios, Dave Westman described Galaxyzoo.org, the Zooniverse and related radio applications, Eve Klopf discussed radio activities at Oregon Tech and asked about suggested radio astronomy projects, and Stuart Rumley told us to throw away our QST magazines because they are near-useless and instead get QEX magazine, Microwaves & RF magazine and the Microwave Journal. Getting back to scheduled presentations, Tushar Sharma traveled originally from India to Canada and then to our conference to present Radio Jove Instrumentation and Education Outreach. This was a personal tour describing his path of motivation and achievement in which radio observation of a solar eclipse was a life-changing experience. Tushar moved from India and attended university in Calgary, Alberta, Canada, where he received help and encouragement from SARA member Bruce Rout over a 5 year period. Maria Spasojevic, Senior Research Associate in Stanford’s VLF Group, was introduced by SARA director Keith Payea, and, remarkably, he pronounced her name correctly. Maria spoke on Quantifying the Role of Wave-Particle Interactions in Controlling the Dynamics of the Earth’s Radiation Belt. We learned how scientists use these to study Earth’s electric fields and magnetosphere, including the Chorus and Whistlers, radio manifestations at extremely low and very low frequencies of particle interactions. Next, Leif Svalgaard’s presentation Radio, Ionosphere, Magnetism, and Sunspots, gave us a history of Earth’s magnetism measurements dating back to the early 1700s, which until relatively recently did not use electronics in any way. His premise is that by working backwards using long-term data dating back hundreds of years, we may be able to better understand the Sun. Leif is a Research Physicist at Stanford. Phil Scherrer brought us up to date with Viewing the Sun, Inside and Out with SDO. Attendees at this year’s conference who also attended the 2012 SARA Western Conference recognized Phil, who at that time described the new Solar Dynamics Observatory spacecraft to us. This time, Phil gave us a complete update of what has been discovered as well as

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new questions resulting from the research. We got to see one of the 4k x 4k imager wafers, one of 50 that were manufactured to get six flyable units at a total cost of 2 million USD. Money well spent in our opinion! Jack Welch then discussed Low Noise Feeds for the Allen Telescope Array. The ATA, which is located in Northern California, uses offset Gregorian dish antennas and originally was built for SETI purposes but presently is used both for SETI and “regular radio astronomy”. The present feed system for the antennas was modified with a glass bottle enclosure to cool not only the low noise amplifier but also the entire log periodic antenna used in the feed system. The modified feeds have been installed on a few dish antennas with the remainder planned for installation over the next year or so. Jon Richards, Senior Software Engineer at the ATA, presented The Signal Search at the Allen Telescope Array. In particular, he described a narrowband search mode with 1 Hz resolution and the automation used to alert personnel of possible contact by alien life. The system looks for signal signatures that are thought to indicate intentional transmissions. There are several “hits” per day and all are investigated in detail. Many have been extremely weak signals from far-away spacecraft or other manmade signals, but “the search continues.” Jon mentioned an experiment using one of the NooElec SDR dongles (mentioned by Ken Redcap earlier) and he demonstrated his use of the free baudline.com software for signal analysis. Of the many activities associated with SARA Western conferences, one is the drawing for items related to amateur radio astronomy. Each registered attendee receives a numbered coupon and one duplicate at a time is pulled from (in this case) Ken Redcap’s red cap until everything has been given away. This year SARA gave away several NooElec SDR dongles, a SuperSID Kit including a USB soundcard dongle, SARA documentation CD sets, and an RS232 to digital/analog converter interface. Another tradition of the SARA Western conferences is the social gatherings at local restaurants in the evenings. On Friday evening several attendees walked from the Marriott Courtyard hotel in Los Altos to Hobee’s for a variety of southwestern style food. Here we met a local skydiver who by chance also was interested in radio astronomy. On Saturday evening we all met at Celia’s Mexican Restaurant on El Camino Real, also within walking distance, for margaritas and Mexican dishes. By the way, the Marriott Courtyard was a good choice and we appreciate Lorraine Rumley’s work in securing it as the operations base for the conference. If you did not attend the 2015 SARA Western Conference, you missed wonderful technical sessions and a chance to learn from and talk to your friends and colleagues and scientists from Stanford University. We are grateful to Stanford and especially Debbie and Phil Scherrer for their help and hospitality.

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SARA Annual Conference at NRAO 2015 Annual Conference Keynote Speaker

Duncan Lorimer from West Virginia University Department of Physics and Astronomy has agreed to be the Keynote Speaker at the 2015 Annual SARA Conference to be held June 20 to 24 at the National Radio Astronomy Observatory (NRAO) in Green Bank, WV. The following excerpt is from WVU website:

I’m an astronomer interested in compact objects (black holes, neutron stars and white dwarfs) which I study using radio pulsars: rapidly spinning, highly magnetized neutron stars. Pulsars are great fun to study and have lead to a lot of exciting adventures over the years. A nice behind-the-scenes article describing how this work is

carried out can be found here .

I arrived at WVU in May 2006 from the Jodrell Bank Pulsar Group where I worked as a Royal Society Research Fellow. Before that I was at Arecibo Observatory (1998-2001) and at the MPIfR in Bonn (1995-1998). My research revolves around surveys for radio pulsars and what they tell us about the population of neutron stars. This work is carried out with many collaborators and uses some of the classic radio telescopes around the world. Of particular interest are young, energetic pulsars and binary systems where the orbiting companion is a white dwarf, a main sequence star, another neutron star, and (perhaps soon!) a stellar-mass black hole.

SARA 2015 Conference Abstracts Author: Professor Duncan Lorimer Title: Pulsars, flickers and cosmic flashes: the transient radio universe Abstract: I will describe a brief history of discovery and some exciting recent developments in the world of pulsars and fast radio bursts. Pulsars, rapidly rotating highly magnetized neutron stars, were discovered in 1967 and continue to surprise and delight astronomers as powerful probes of fundamental physics and astrophysics. Fast radio bursts are millisecond-duration pulses of currently unknown origin that were discovered in 2007. Both pulsars and fast radio bursts have great promise at probing the universe on large scales and in fundamental ways. I will describe the science opportunities these phenomena present, and discuss the challenges and opportunities presented in their discovery.

Author: Tom Hagen

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Title: Portable VLF Receiver for Making Calibrated Magnetic Field Strength Measurements Abstract: This presentation is about the author's continuing efforts to get calibrated measurements of the field strengths of the various VLF stations used by the SuperSID program as reference sources to detect sudden ionospheric disturbances (SID’s). Presently, the amplitude of data coming in from the various SuperSID stations around the world is uncalibrated. When a SID is detected, there is a measurable change in relative signal strength, but actual field strengths are unknown. If a portable VLF receiver and loop antenna setup could be developed that is calibrated, then such a setup could be shipped to different sites for calibrated field strength measurements. Users could even build their own receiver and loop antenna from standard plans. A small loop design and two receiver designs are discussed. Estimated sensitivities of each receiver design are calculated. Calculations are verified with laboratory tests.

Author: Ken Redcap (KR5ARA) Title: 611 MHz Total Power Radio Telescope - Part 0x03 (Software) Abstract: Part 0x02 of this presentation was given at the SARA 2014 East Conference. Parts 0x01 and 0x02 dealt with the hardware (antennas (< $100 each), USB dongle (< $30), etc.) being used for this ongoing project. Part 0x03 will focus on the programs available on the website SDRSharp.Com and how to make modifications. Other topics will include Visual Studio (Microsoft) used to build the application SDRSharp and an introduction to the new hardware (AIRSPY ($200)) available on the same website that is compatible with SDRSharp. This project is a work in progress and is my first effort on a radio telescope to detect energy in this frequency range. The telescope is being set up at the McMath Hulbert Solar Observatory (MHO) in Lake Angelus, MI. All electronic components and antennas required were purchased from Amazon except for the low noise amplifier. All freeware software components were derived from sites with various versions of SDR# like SDRSharp.Com. Inspiration for the project comes from Curt Kinghorn's presentation at the 2013 SARA Western Conference on low cost radio telescopes using off-the-shelf TV receive antennas and an article in the August, 2013 SARA Journal about a low cost HI receiver.

Authors: Dr. J. Wayne McCain, Professor and Kevin Keenan, Student Title: SARA/JOVE Activities In A College-Level, Management Of Technology (MOT) Curriculum Abstract: The Management of Technology BS degree program within Athens State University’s College of Business is a specialized management degree with particular emphasis on technical risk management,technology innovation management, and overall assessment, identification, acquisition, and implementation of technology within an organization. Specific case studies are used to illustrate MOT principles and provide students with as many ‘hands-on’ experiences as possible. One such activity has been the development of the Athens State University Radio JOVE Observatory (ASURJO) which includes not only participation in the NASA-Sponsored and SARA-supported Jupiter decameter emissions monitoring program (Project JOVE), but also the Stanford Solar Center/SARA Super-SID solar disturbance monitoring program, and general amateur radio astronomy observing. Student activities have included receiving hardware and antenna construction/installation; monitoring/recording/reporting software implementation; general facility design, construction, and maintenance; along with development of related research paper topics and open student ‘star parties’. This paper gives an overview of faculty and student activities with examples of student work

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accomplishments which might serve as guidelines or inspiration for other college-level, radio astronomy-based involvement.

Author: H. Paul Shuch, N6TX Title: Who Speaks for Earth?

The scientific Search for Extraterrestrial Intelligence (SETI) has, for the past 55 years, centered primarily on observational research into electromagnetic emissions reaching Earth from space. But, there have been sporadic efforts to reverse the experiment, instead transmitting messages from Earth toward our possible cosmic companions. Recent technological advances now put the equipment required for METI (Messaging to Extraterrestrial Intelligence) within the capabilities, reach, and budget of a wide range of institutions, businesses, and even individuals; thus, METI activity is on the rise. The scientific community is sharply divided about the advisability of METI, with several SETI organizations now taking stands, pro and con. This paper will discuss the legal and societal implications of transmission from Earth, summarizing arguments for and against, so that such policy-making bodies as the International Academy of Astronautics SETI Permanent Committee might better consider the big picture.

Author: Paul Oxley Title: RASDRviewer Pulsar Feature Update Abstract: The author published a paper in the SARA Journal titled “RASDRviewer PULSAR FEATURE DESCRIPTION”. This paper summarizes the Journal Article and enhances the content based on the learning that has occurred since its publication. The major enhancements are in the processing capabilities available in RASDRviewer, the addition of a simulator and the addition of references to the TEMPO program that can be used to aid in establishing the Pulse Period range. Changes to the original Journal text have also been included based on questions and comments received since its publication. The Journal Published document described the proposed process for capturing a pulse from a Pulsar. The objective of the process is to be able to display and record the pulse profile during the period when the Pulsar is within the beam width of the antenna. The process works in near real time on a high end Windows PC. The process uses In phase and Quadrature (I & Q) samples that are presented to a Fast Fourier Transform (FFT). The FFT output is entered into an accumulation matrix of time verses frequency bins. The accumulated values are coherently integrated to improve the Signal to Noise Ratio (S/N). The Time difference between each FFT is varied to allow the selection of the appropriate slope (DT/DF) that will cancel the dispersion present in the Pulsar data. Further processing is accomplished using a lower frequency clock rate to identify both the fundamental frequency of the pulse and its phase. The low frequency clock is locked to this phase to allow further coherent integration (Folding).

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Author: Curt Kinghorn Title: Graphic Radio Astronomy Data Abstract: Most amateurs with total power radio telescopes take data in the form of drift scans. Drift scans take samples periodically from antennas aligned either north or south that are raised to a desired declination. The data is typically recorded in the form of strip charts, either paper or electronic. Many people say, when looking at the squiggly lines produced by drift scans, “All I see is squiggly lines. Unless you show me a picture, I don’t get it!” But, it is hard to convert this drift scan data to maps. This presentation will show several ways to convert strip recording chart data to maps and show such maps made from real data.

Author: Carl Lyster Title: Field Demonstration of the Radio Astronomy Supplies SpectaCyber Radio Astronomy Receiver Abstract: The Spectracyber has been in continuous production since the early 90’s. It has evolved as the electronics industry has changed over the decades but still retains the same basic analog design and is the culmination of the inventor’s dreams since age 15! The unit is optimized to deliver very impressive Hydrogen Spectra from a simple 10 foot TVRO dish and can give very good results with as little as a 3 foot horn. The lowest noise figure components commercially available are used in the front-end along with custom manufactured RF filters in all of the necessary places. The triple conversion design uses a unique single quartz crystal for both first and second local oscillator injection. A simple stepped PLL oscillator performs the third conversion to the final IF for amplification and detection. A true square-law detector feeding adjustable DC gain and integration stages is digitized by a 12 bit A/D converter and sent out over RS-232 data lines at 2400 baud. Data can be transferred via an RS-232 to USB cable with Windows 7. A typical 400 point spectrum can be gathered in less than 1 minute with a measurement accuracy of 1 km/second. The maximum scanning range is +/- 400 km/second from hydrogen rest. Red and blue shifted spectra are displayed on a color graph in real time and can be saved and played back in fast motion to present a “movie” of the passage of Hydrogen clouds through the beam of the antenna. Remote site operation of the software is possible through several commercial programs such as “Go To PC” etc. Each Spectracyber is hand built from hundreds of surface mount components and represents approximately 100 hours of construction and testing time per unit.

Author: Ciprian Sufitchi Title: Detecting meteor radio echoes using the RTL/SDR USB dongle Abstract: The Software Defined Radio (SDR) has become a popular concept for radio astronomers and radio amateurs. Inexpensive implementations allow hobbyists to dedicate SDR devices for various experiments such as monitoring radio echoes originating from meteors, as they enter the atmosphere. In particular, the "RTL-SDR USB receiver" is a very affordable SDR that uses a DVB-T TV tuner dongle based on the RTL2832U chipset. Priced of $15 per unit (approximately), this entry level SDR, when connected to a standard computer, represents an interesting option for monitoring meteor scatter activity 24 hours a day. This paper describes a practical method to receive meteor radio echoes and explains how the web site livemeteors.com works."

Author: Skip Crilly Title: Shannon Entropy Measurements of Radio Telescope Signals

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Abstract: A two-element 5.4 m dish interferometer system is described. The telescope system is used to observe celestial objects at 1405 to1452 MHz using a software-cross-correlator, and is used for SETI. Observation of the Crab Nebula is presented. One dish measures potential short duration frequency-variable modulated pulses, hypothetically of ETI origin. A speculative pulse decoder has been programmed into the twelve million channel, 3.7 Hz bin receiver. SNR and Shannon Entropy is calculated for each decoded symbol. This paper will describe the radio telescope and some unexpected low probability events that imply a requirement for further analysis and follow-up.

Author: Steve Tzikas Title: New SARA Sections Abstract: The Introduction to SARA Sections has the goal of providing a vision and process to help SARA enhance itself in the near, intermediate, and long-term future. It is proposed that by incorporating a sectional basis to the activities performed by SARA, that many organizational pursuits will have a structure to fulfill themselves. Goals include, but are not limited to, strategic planning, standardized data collection, methodologies and protocols, and member empowerment via section coordinators and assistant coordinators. This presentation will involved a discussion centered around the recently posted SARA sections and how they can be used to transformed SARA by bench-marking opportunities with organizational structures from other well established amateur astronomical organizations.

Author: Bascombe J. Wilson Title: Developing a Radio Astronomy Program For Community Observatories Abstract: This paper aims to share the experiences of the Little Thompson Observatory (LTO) of Berthoud, Colorado, as the facility added radio telescopes to its robust program of astronomy education and hands-on experience for students, their families and the community. The experience at LTO may be helpful to other observatories and community science centers that may be considering the implementation of a radio astronomy program. The paper focuses less on the technical aspects and more on the programmatic and management issues of such an undertaking because as a rule the technology can be bought off-the-shelf or built rather directly, but creating a program from scratch, attracting support, and demonstrating success requires much more than antenna dishes and radios. The hardest challenges in getting started aren’t technical—Maxwell worked most of the technical stuff out (OK, he was helped a little by Jansky, Reber, Kraus and some others) —but organizational, budgetary, interpersonal and operational considerations enter into every single scientific undertaking, and often they are the toughest part of the equation.

Author: Various Title: Open Mic Session This speaker’s slot will be reserved for shorter presentations (~10 minutes or less) for partially completed projects, general questions to the SARA audience, or other humorous or entertaining topics. This was a successful format at the 2015 West conference in Palo Alto CA.

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Call for Papers: 2015 SARA Annual Conference Final versions of papers for the Society of Amateur Radio Astronomers (SARA) 2015 Annual Conference are due no later than 4 May. Be sure to include your full name, affiliation, postal address, and email address, and indicate your willingness to attend the conference to present your paper. Submitters will receive an email response, typically within one week. Guidelines for presenter papers are located at:http://radio-astronomy.org/pdf/guidelines-submitting-papers.pdf Formal printed Proceedings will be published for this conference and all presentations can be made available on CD. Tentative Schedule Sunday 21 June, will start with an introduction to Radio Astronomy at the Science Center classroom, followed by learning to operate the forty foot radio telescope (1,420 MHz (21 cm). Presentations by SARA members and guests are scheduled on Monday and Tuesday. A High Tech tour of the NRAO facility will be conducted on Tuesday 23 June.

Feature Articles

European Solar Eclipse Observed by Radio Waves Christian Monstein The Sun radiates not only at visual wavelength but also in ultra-violet, X-rays and, among others, also at radio wavelengths. The institute for Astronomy at ETH Zurich has operated two small radio telescopes for more than 30 years at Bleien Observatory, about 50 km south of Zurich. These use 5 and 7 m parabolic dish antennas connected to CALLISTO frequency agile radio spectrometers, which are used as cheap and reliable back-ends. In the future they will be replaced by high speed, high dynamic FFT-spectrometers to improve sensitivity and resolution in the time and frequency domains. Both dish antennas were originally designed and built explicitly for solar radio observations. Despite the considerable research at ETH and elsewhere, one of the burning questions is what causes the Sun’s coronal heating. There are many theories about it but none of them can cleanly and clearly explain how the high coronal

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temperature of millions of kelvins is produced. A solar eclipse, such as the one of 20 March 2015, is ideal to study the geometrical structure and temperature at different heights above the Sun surface. The telescopes at Bleien Observatory track the sun automatically every day from sunrise to sunset independent of weather conditions. Radio telescopes such as these can observe the Sun through clouds and rain with only minor attenuation of the received emissions. In figure 1 we see three light curves of the 20 March eclipse produced by the 7 m dish antenna. The dish antenna is shown in figure 2.

Fig 1: ~Light curves of three frequencies in UHF range observed with the 7 m dish antenna, which tell us something about the dimensions and temperatures at higher layers in the solar corona. The traces show sunrise around 06:15 UT and around 08:30 UT we observe a decrease in the radio flux due to shadowing of the Moon disc during the eclipse on 20 March. Maximum occultation of the Sun by the Moon corresponds to the minimum in the light curve at around 09:30 UT. Close to 11 UT the partial eclipse is finished and the radio flux remains constant until about 16:30 UT except for some negative drift due to temperature changes. Sunset is around 17 UT and we can see that even the bushes and trees at the horizon radiate at radio frequencies with a level of 1 ... 3 sfu (solar flux unit).

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Fig. 2 ~ Parabolic dish 7 m diameter for observing from 100 MHz up to 4000 MHz in dual circular polarization at Bleien Observatory. The radio telescopes continue tracking the Sun even below the optical horizon due to refraction. Therefore, at radio wavelengths we can observe the Sun a few minutes longer than at optical wavelengths. Shortly after 17 UT every night the antennas are automatically parked at a fixed 180° azimuth and 30° elevation as preparation for the following day. The radio flux at the parked position is less than 1 sfu (Note: 1 sfu = 10 000 Jansky = 10-22 W/m2/Hz). The strongest radio source in the sky radiates in the order of 2000 Jansky, corresponding to 0.2 sfu. In figure 3 we observe the light curves of the eclipse received at microwave frequencies between 1000 MHz and 1256 MHz with the 5 m dish. These frequencies correspond to wavelengths of 30 cm to 23.8 cm. This frequency range will be used in the future for cosmological observation of the low red-shifted hydrogen line. In the case of the Sun, these wavelengths are radiated from lower layers in the corona where the temperatures are just a few thousand kelvin. The light curves for some frequencies show oscillations during sunrise and sunset. This is interference between the direct radiation received from the Sun and reflected radiation received from the ground. And in figure 4 the same eclipse was also observed at Humain which is the radio telescope location of the Royal Observatory of Belgium (ROB). It’s again a Callisto hooked up to a 6m parabolic dish, tracking the sun.

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Fig. 3: ~Light curves of 5 microwave frequencies received by the 5 m dish have a similar shape to those seen with the 7 m dish.

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Fig. 4: ~Light curves of 5 different meter-wave frequencies, received by a 6 m dish at Humain, Belgium. Christian Monstein ETH Zürich Institute for Astronomy Wolfgang-Pauli Strasse 27 8093 Zürich email: monstein@astro.phys.ethz.ch

2011 Annual SARA Conference

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Coronal Mass Ejection Effects on HF Radio Propagation at Anchorage, Alaska 17 March 2015 Whitham D. Reeve Radio: Sudden frequency deviations of WWV and WWVH on 10 MHz, peak-to-peak deviation approximately 33 Hz. Chart covers time period 0441 to 0454 UTC. Note: Anchorage sunset: 0404 UTC (2004 AKDT).

Geomagnetic: Geomagnetic sudden Impulse coincident with SFD at 0445 UTC with deviation: 54 nT. Chart covers a 24 h period. The sudden impulse was likely caused by the full-halo coronal mass ejection observed early on 15 March (see image next page). Geomagnetic storm conditions quickly developed after the SI. Additional storm conditions followed later, likely caused by a recurring coronal hole high-speed stream.

Sudden Impulse at 0445

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Sudden impulse as received at Anchorage, Alaska plotted as horizontal component determined from original X- and Y-component data. Data plotted at same time scale as Argo chart on previous page. Data sampling rate 0.1 Hz. Image © 2015 W. Reeve

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Influence of Coronal Hole High-Speed Stream

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Solar: Coronal mass ejection imaged by SOHO LASCO C2 on 15 March 2015. The CME impacted Earth’s magnetosphere at 0445 on 17 March. Image courtesy SOHO (ESA/NASA)

How to read charts: In the radio section, the Argo chart is a form of narrowband spectrogram, which shows the received frequency after SSB detection. The Icom R-75 receiver is set to USB and its frequency is tuned about 1 kHz below the carrier frequency of 10 MHz. Therefore, the trace shows an audio trace as proxy for the actual 10 MHz carrier. Time in UTC is shown on the horizontal scale (1 min time stamps) and frequency in Hz is shown on the vertical scale. The frequency span shown is about 40 Hz. Relative intensity of the received signal is shown by the brightness of the trace. Two charts are shown in the geomagnetic section. The first is a 24 h magnetogram produced by the SAM-III magnetometer and SAM_VIEW software. Time in UTC is shown on the horizontal scale and magnetic field flux density (magnetic induction) is shown on the vertical scale. The traces show the three field components Bx, By and Bz (key is in the lower-left corner). The software normalizes the field measurements at the beginning of each day, so the trace amplitudes are relative to the field values at 0000 UTC. The second chart is an Excel chart produced from the SAM-III data. It is a zoomed-in trace of only the sudden impulse. Time in UTC is on the horizontal scale and field flux density on the vertical scale. The trace shows absolute flux density and is not normalized. The image shown in the solar section is a false color image produced by the LASCO spacecraft. The outline of the Sun is the white circle in the center of the occulting disc on the spacecraft imager. A movie of the CME leaving the Sun is here: http://sohowww.nascom.nasa.gov/pickoftheweek/Earth_boundCME_C2_best.mp4

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Strong RFI Observed in the Protected Deuterium Band at Bleien Observatory, Switzerland Christian Monstein Beginning in December 2014 strong sporadic radio frequency interference (RFI) was observed at Bleien Observatory in the frequency range 200 to 450 MHz. The intensity was stronger than the quiet Sun. It usually started around 0600 UT and lasted 10 to 20 minutes. On weekends, Saturday and Sunday, the RFI was on for at least one hour and sometimes up to 4 hours. Coincidentally, the nearby farmer lamented that he could not listen to DAB-T anymore and therefore procured a new radio receiver. Unfortunately, listening was still not possible with the new receiver in the morning and weekends. I sent a short report to the Federal Office of Communications of Switzerland, OFCOM, about the facts found so far, and we discussed several procedures on how to identify the RFI source. The farmer and I started to note times of RFI and we compared the results. We noted that when I could not observe the radio Sun below 1 GHz due to the RFI, the farmer’s family could not listen to the radio. However, we were unable to identify the RFI source. On March 11, I went up to the observatory at 0500 UT to make live observations of the RFI and to find its direction. I planned to use the 7 m dish antenna over a 50° to 270° azimuth range and 5° elevation in both left-hand and right-hand circular polarizations. Unfortunately, I was 45 minutes late and the RFI shown in figure 1 had already ceased. I went up even earlier on March 12 at 0400 UT. I positioned the 7m dish at 108° azimuth and 4° elevation, directly at the farmer’s house, and just waited while watching the spectrometer display. At precisely 0620:20 UT the RFI suddenly appeared very clear and strong as seen in figure 2. I immediately called the farmer by phone and asked for permission to conduct radio measurements in his home, see figure 3. He said yes, so I started direction finding using the handheld spectrum analyzer and directional antenna shown in figure 4. I found nothing serious on the ground floor but detected strong RFI on the 1st (upper) floor, the flat of the farmer’s son Samuel and his girlfriend. The living room showed strong RFI in all directions. To isolate the noise source we switched off all electrical gadgets one at a time including smart-phone chargers, coffee machine and the lights. As soon as the light was switched off, the RFI disappeared, see figure 4 at 0628UT and 0632UT. We pulled all illumination devices one at a time and found that an LED lamp in figure 6 was the source of RFI. The light had been ordered at the beginning of December 2014 from the web-shop LED.CH. The only information available on the LED and on the box is: MR16 3*1W 12V WARM WHITE CE. Now, with the LED off we can observe the Sun again and the farmer’s family can listen to DAB-T.

Abbreviations DAB-T: Digital Audio Broadcasting – Terrestrial LED: Light Emitting Diode RFI: Radio Frequency Interference UT: Universal Time

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Figure 1 ~ RFI on Wednesday, 11 March 2015 early morning 07:10 local time, the usual time when people get breakfast bevore going to work. On this day, I was too late to track and identify the source of RFI.

Figure 4 ~ RFI spectrum on Thursday, 12 March.2015. LED was switched on at 06:21 UT to enjoy breakfast and light was switched off around 06:28 UT for checking. At 06:32 UT the LED was removed from the installation.

Figure 3 ~ 7 m dish left pointing to the Moon with the farmers’ house in the background right. Samuel's living room is on the 1st (upper) floor right-most window.

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Figure 4~ Logarithmic periodic dipole array (LPDA) from AARONIA, type HL 7040 covering 700 MHz – 4 GHz (left) and 2.7 GHz RF Spectrum Analyzer PSA2702 from TTi (right) connected via a thin SMA coax cable to the LPDA. Frequency range was adjusted to cover 200 to 400 MHz. For spectrum, see figure 5.

Figure 5~ Observed spectrum close to the RFI-producing LED in 1st floor of Samuel Brunners home. The antenna low frequency design limit is 700 MHz (!); nevertheless quite some power was received, much stronger than the quiet Sun‘s radio radiation.

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Figure 6 ~ Guilty LED of type MR16 3*1W 12V WARM WHITE (CE), procured from LED.CH for CHF 28.60 per unit. The LED was parallel to a few other incandescent lamps and was driven by a 12V ac-transformer.

Meet the author: Christian Monstein is a native of Switzerland and lives in Freienbach. He obtained Electronics Engineer, B.S. degree at Konstanz University, Germany. Christian is a SARA member since 1987 and is licensed as amateur radio operator, HB9SCT. He has experience designing test systems in the telecommunications industry and is proficient in several programming languages including C and C++. He presently works at ETH-Zürich on the design of digital radio spectrometers (frequency agile and FFT) and is responsible for the hardware and software associated with the e-CALLISTO Project. He also has participated in the European Space Agency space telescope Herschel (HIFI), European Southern Observatory project MUSE for VLT in Chile, and NANTEN2 (delivery of the radio spectrometer for the

Submillimeter Observatory at Pampa la Bola, Chile). Currently he is quite involved to prepare the radio telescopes for cosmological test observations at Bleien observatory. He is a member of the steering committee of ISWI at UN office for outer space affairs in Vienna. And he plays also the role of a coordinator of SetiLeague in Switzerland. Email: monstein@astro.phys.ethz.ch

1.4 GHz radio telescope Part 1: Selecting a Software Designed Radio (SDR), using it, getting data out of it, and spectrally analyzing that data By Kenneth Kornstett Abstract Part 1 is about a 1.4 GHz radio telescope project to obtain the spectrum of the galactic hydrogen doppler signal. The SDR and a Fast Fourier Transform (FFT) are used to get the spectrum. Since the RF front end to the SDR does not yet exist, a standard FM radio station signal is used to simulate the galactic hydrogen doppler signal. This paper describes the selection of the SDR, use of it, extraction of data from it, and finding the spectrum of that data with a FFT.

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1. Introduction A 1.4 GHz radio telescope can be used to obtain the spectrum of the galactic hydrogen doppler shift at different galactic longitudes. After converting each doppler shift data into a spectrum, the velocity can be calculated then a galactic rotation curve can be created. Such a curve is used to calculate galactic mass. The 1.4 GHz telescope will have a RF front end and a SDR. The SDR data will be converted to a frequency spectrum via a FFT. This paper is part 1 of that system because the RF front end has not been built yet. Without a real signal, a wideband FM signal will be used to simulate the galactic hydrogen doppler shift signal (both are spectrums). A FM radio station will be used as the simulated signal. This paper will examine the SDR in four parts: selection of a SDR, use of a SDR, extraction of data from a SDR, and spectrally analyzing that data with the FFT. 2. How I selected a SDR A receiver trade study and literature survey are described that led to selecting a SDR. 2.1 Receiver architecture trade study To obtain the frequency spectrum of the galactic hydrogen doppler shift, one uses a spectrometer. There are three ways in radio astronomy to obtain the spectrum: 1) spectrum analyzer [1], 2) analog spectrometer (channelized receiver with parallel filter banks) [2], or 3) digital spectrometer (SDR and FFT). I did not have access to a spectrum analyzer, and I did not want to buy one because of the cost. The second method reference describes a board that has several analog filters tuned to different frequencies. I am aware of a channelized receiver that used fixed frequency filters. Unless fixed frequency filters (expensive) are used, then tuned filters would have to be used. Since, I did not have a signal generator to tune the filters, I would need to buy one or build a signal generator. I did not want to buy a signal generator, so I looked at building one. I found a cheap synthesizer chip (Analog Device AD9850/AD9851 dds module) for less than $20. But, I would have to use a computer or switches to enter frequency data into that chip to produce different frequencies in order to tune the different filters. Cost and construction time were an issue with building a channelized filter bank and signal generator. The SDR and FFT method was attractive because only the SDR would be needed. The FFT could be done in software. The SDR had several important features: wide frequency range, high sample rate, wide bandwidth, and digital output. I knew that I could use the FFT on digital data to find the frequency, so that was a plus factor. Already being in a digital format, the data was in the computer and would not have to be input into the computer later. The SDR and FFT method was the cheapest solution and no construction time was needed. Also, it would allow me to experiment with the SDR. Two immediate questions were: 1) how steep would the SDR learning curve be and 2) would the SDR 8 bit output be enough for a the galactic doppler low level signal? The simple trade study had pointed toward the SDR but with concerns. The RF front end for the SDR and FFT method would only require an antenna, Low Noise Amplifier (LNA), and band pass filter. (A second amplifier after the LNA might be needed depending on the gain of the SDR.) 2.2 Literature/information phase I found so much information on the internet, that I was reminded of the old expression about drinking from a fire hose. I soon discovered that the SDR had been used for obtaining the 1.4 GHz doppler shift data, so proof of concept for the SDR used as part of 1.4 GHz system had been demonstrated. I quickly found that 8 bits was adequate to detect galactic hydrogen signal because other people had used an SDR and FFT to plot galactic

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doppler spectrum curves. For the other SDR concern, a steep learning curve, I decided that based on personal experience with early microprocessors and digital signal processors, I could learn to use a SDR. Now that I had chosen the SDR approach, I researched the SDR in more detail. The history of the software radio goes back a few decades. I forgot that I had once worked in the same building at the company that coined the phrase “software radio” [3]. That system was very large compared to the modern SDRs. There are two modern types of SDRs that can be separated by size and cost. The smaller SDRs are thumb sized and attach to a laptop computer via a USB connector. Power is supplied to the SDR via the USB connector. Such a small USB system is often called a dongle. The bigger modern SDRs fit in a small box. Cost wise, some dongles are cheaper than the box sized SDR that can cost up to several hundred dollars. This paper is only concerned with the small and cheap ($20) SDR dongle. One popular cheap SDR was originally used to decode European type television signals, but enterprising individuals figured out (hacked) how to use it as a digital receiver [4]. 2.3 How I chose a SDR (more literature/information search) The next problem was to physically select a SDR. The trade study had convinced me to try a SDR, so I continued the literature search. To reduce that amount of information, I began by selecting what computer I wanted to use the SDR with. Modern SDRs can be used with Windows or Linux operating systems. I decided to use Windows because I had a Windows 7 x64 laptop. Also, I would use free programs (applications) that did not require programming. Those decisions reduced the web searching. Basically the small thumb size USB SDR has two chips inside: a tuner chip and a demodulator. The tuner chip down converts the RF signal, and it determines the input frequency range. The tuner chip that had the biggest frequency range was the Rafael Micro R820T which went from 24 to 1766 MHz [5]. That would work fine for my 1.4 GHz system. The tuner obviously had an oscillator, mixer, and filter inside the chip. I decided to use a SDR with the R820T tuner chip. The second chip (demodulator) detected the signal and output a digital signal. I found that the Realtek RTL 2832U demodulator chip was used in many SDRs. I decided upon the RTL 2832U with R820T tuner chip for several reasons. First, I discovered that this SDR has been used in a 1.4 GHz system described in the SARA Journal [6]. Another 1.4 GHz system using this SDR but using the Linux operating system is found on the internet [7]. Second, this chip was available from different suppliers. Third, it was very cheap. Prices range from about 10 to 22 US$. In particular, I chose the NooElec R820T SDR & DVB-1 SDR for several reasons. In addition to having both of the above tuner and demodulator chips, it had electrostatic protected diodes on the RF input so I would not accidently short out the SDR. Some SDRs do not have such protection. Also, it was available from Amazon for just over $22 plus shipping (cheaper now). They are cheaper from other sources, but I felt more comfortable using Amazon as a source. With respect to my future 1.4 GHz galactic hydrogen system, I now had the digital part (the heart) with the purchase of this particular SDR [8]. In the literature search, I found a web site for using the RTL SDR dongle for meteor detection [9]. However, it is probably too much trouble to build a meteor system based on the SDR (just use a FM radio). A SDR intensity interferometer is described in two papers [10]. 2.4 What came with my SDR (from Amazon) The SDR came with a small monopole antenna (with no ground plane) and a remote control for European television. I put the remote control in a drawer and forgot about it. By the way, there were no instructions. The SDR RF connector was a female MCX type (similar to a small SMA type), but the male connector (from the antenna to the SDR) pushes in rather than screwing in. I also ordered a short cable to connect the SDR to a type

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F connector from Amazon for $6 (anticipating getting my 1.4 GHz system built). I selected the short cable because I thought that a MCX to type F adapter may stress the SDR dongle. The SDR and monopole antenna are shown in Figure 1. The size of the SDR and antenna can be compared to the enclosed red thumb USB drive.

Figure 1. NooElec R820T and SDR & DVB-1, included antenna, and a thumb drive (for comparison). The monopole antenna has been reported to be bad (junk) by many people on the internet, but I have had good reception with it. I read somewhere on the internet that one needs to put a drop of glue where the tiny coax cable enters the base of the monopole to keep from accidently pulling the coax cable out of the base of the antenna. I did that immediately after determining that my SDR worked. I have also read that some antennas were not connected inside the antenna base which sounds like bad quality control. (Perhaps, NooElec has better quality control.) The antenna base has a magnet so it will attach to metal surfaces. The SDR plugged into the laptop is shown in Figure 2. Notice that the USB connector does not seem to completely fit into the USB socket, but it works. The SDR disconnected a couple of times while I was using it. I fixed that by running the SDR tiny coax cable over the power cord instead of under the power cord. One may want to put a support under the SDR dongle (like a small book). By the way, this SDR does not work with USB 3. Also, I have read that one should not use a long USB cable with the SDR. If I get noise in the SDR later when I connect it to the RF front end, I will put tin foil around the dongle to shield it (Faraday shield) from computer laptop noise.

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Figure 2. NooElec R820T and SDR & DVB-1 attached to laptop and monopole antenna

3. How I got the SDR to work In this section, how to install software to receive signals on the SDR is described. In addition, a program to track planes that are equipped to transmit certain digital signals will be briefly described. It has nothing to do with radio astronomy, but it was fun to use. 3.1 Installing the SDR on a Windows computers While waiting for the SDR to arrive in the mail, I continued to search on the internet and watch SDR related videos. Appendix 1 contains a brief list of Windows SDRSharp (or SDR#) instructions that I wrote for a friend. Appendix 2 has hints for that installation. For windows 8 (or Linux) one should google SDRSharp installation instructions. I used the x32 version which worked fine on my Windows 7 x64 laptop. 3.2 Using the SDR As encouragement, within 30 minutes of starting the installation, I was receiving a normal US FM radio station with the SDR. After installation of the SDRSharp, instructions for using the SDR are found in Appendix 3. To begin using the SDRSharp application, double click on the blue SDRSharp ICON in the unzipped folder (Figure 3). When the display comes up, in the upper left corner, select RTL-SDR/USB in the Source window. (This is the only time that you will have to do that.) Click on the play button (second button in upper left).

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Figure 3. SDRSharp Icon to start the program The SDRSharp screen comes up as shown in Figure 4. The screen will have two graphical displays and a control panel. The graphics displays can be dragged around on the monitor screen with the mouse. In this figure, the spectrum is shown on top and the waterfall display underneath the spectrum. To the left is the control panel. In the top of the control panel there are several symbols. The second symbol in this picture is a black square box (pause). When your display first comes up, it will be a play button symbol (sideways arrow head). It is the run/pause button. Under those controls is a compartment entitled source, it should indicate that you have a RTL SDR USB installed. Under that control is another box entitled radio and it has modulations to be selected. Wideband FM (WFM) is selected in the figure. Just click on the desired modulation button to select it.

Figure 4. SDR# display (WFM) Click on the numbers to the right top and enter a FM radio station frequency (e.g. 100,000.000 with no commas). Make sure the WFM button in the radio menu (to the left) has been clicked. If no signal, move the

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mouse on the upper spectrum display to a bump and click on it. If no spectral bumps, check the RF gain by clicking on the gear symbol next to the play button. Move the gain to the right. If no audio, click on the speaker symbol and adjust the audio gain slide to the right of the speaker symbol. Look back at the spectrum display (top) in the figure. Notice that several bumps are shown. You tune to a spectrum bump by dragging the red line (with a mouse) to the bump, or double clicking on the bump, or entering the frequency in the box at the top (click on numbers, enter frequency, then depress carriage return). This is quite manual, but there are SDR programs which act like a scanner. Notice in this figure, some information about the station is shown at the top of the spectrum box. The waterfall display will track the spectrum but it is a time history. The colors of the displays can be easily changed. Notice the lack of a help control. Figure 5 shows another signal being monitored. You may notice that it is a narrow band FM signal. The frequency may tell you that is a US FM weather station. Experiment with the display controls.

Figure 5. SDR# display (NFM).

3.2 Other SDR programs While not radio astronomy applications, there are other interesting SDR programs that can be downloaded and used without programming. Besides the scanner, there is an interesting SDR program included in the SDRSharp download directory. It is called ADSBSharp and the green ICON (to start the program) is shown in Figure 6. You will also need to download a program to display the ADSBSharp program data. I used ADSBScope as shown in Figure 7 (download instructions are found on the internet).

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Figure 6. ADSBSharp ICON

Figure 7. ADSBScope display screen ADSB is Automatic dependent surveillance broadcast which is a digital signal sent automatically by airplanes with ADSB equipment [11]. Since the SDR is a receive only radio, we are actually receiving the signal from an airplane. Most commercial airplanes are equipped with ADSB. Such systems will become mandatory worldwide in a few more years. There are two frequencies but 1090 MHz is the common one that this program is tuned for. I was surprised that the little monopole antenna worked fine at that high frequency. I have run this program for 24 hours at a time and taken screen snapshots. I put the screen snapshots in a video and speeded it up (to show nearby ADSB air traffic). I counted the number of planes per hour from those screenshots, plotted the count, and even spectrally analyzed the curve. I live where there is a lot of air traffic. I have read that some location like Oregon may only get a few airplanes a day. Initially, I did not receive any signals until I raised my monopole antenna up a couple of feet in the air (away from the laptop). If you think your ADSB system is not working, move the antenna first. You may have to go near a large airport to get a signal. The line of sight for my system was over a hundred miles. There is a cheap and easy to make collinear coaxial antenna described on the internet to get more gain compared to the little monopole antenna (google “collinear coaxial adsb antenna”).

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There is a little procedure for turning on the ADSBScope program that can be found on the internet. My difficulty was in the last step, I could not find the last button to push, to cause the program to display. I discovered the correct button by watching an ADSB video on YouTube. Web site http://www.flightradar24.com/36.6,-92.5/7 shows airplane traffic all over the world, and you can zoom and drag the display around to your physical location. Apparently many hobbyists are using plane spotter programs. Again, there are different ADSB programs that do the same thing as described in this paper, but you need an ADSB decoder program and a display program. I turn on the ADSBSharp program then turn on the ADSBScope program. I hacked into the ADSB data stream and was overwhelmed by the amount available. One can fill a hard drive in a short time. I wrote a program to sort the data based on message types, but there were still a lot of data left over. Fortunately, most of the interesting data (flight number, identification number which can be used to look the plane up on the internet, position data, velocity, height, and such things) are displayed on the ADSBScope screen. The ADSB data is both interesting and alarming from a security viewpoint. 4. How to extract data from the SDR In this section, I will describe getting data from the SDR. It is complex data which means that it has two parts: Inphase and Quadrature (I&Q). Both I & Q are 8 bits each and are the inphase and quadrature parts of the signal (out of the demodulator chip). 4.1 Getting data out of the SDR We will use a free program (rtl_sdr.exe) to extract digital data from the SDR. The simplified instructions to download that free program and use it are shown in Appendix 4. Figure 8 is a screen snap shop and shows the steps involved in using that free program (rtl_sdr.exe). Note the comment “Signal caught, exciting!” Also notice that the top of this window says “Command Prompt.

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Figure 8. RTL_SDR screen capture Now, go back to the x32 directory and find the file that you just captured. If you open the file using a text editor like Windows notepad, the file will take some time to display (because it is a large file) and the characters will be unreadable. The binary file must now be converted into a text file (ASCII) to be usable. If you look at Figure 8 carefully, you can see that I went (navigated) to the x32 directory and did a directory command (dir). Next, I did a CD rtl_sdr (change directory) which produced an error saying that it could not find the path. Next, I typed only rtl_sdr which caused the rtl_sdr.exe program to start (just like in the old DOS window of years ago), and the rtl_sdr commands were displayed.

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Next, I typed rtl_sdr –s 2400000 –f 88500000 capture.bin. Then some characteristics of the SDR and the commands are displayed. (Take time to look at them.) After a short time, I depressed control C (lower left key plus the c key) to stop the program. The commands set the sample rate and frequency. The data is stored in capture.bin file. This is described in the appendix. If you just click on rtl_sdr.exe file in the directory, the window will appear then quickly disappear. Thus, one has to use the command prompt (to get the window to stay up). To exit the Command Prompt window, type exit and depress carriage return. 4.2 Converting the binary file to usable data. In Appendix 5, a simple BASIC program is shown to open the binary file, convert it to a text file (ASCII), and store it in an output file. You could use whatever programming language you prefer to accomplish the conversion, just open the file, read and convert the data, and store the data in another file. Time wise, to reflect upon the time spent to get to this point, I got the SDR and had it working within 30 minutes. Two days later, I got the ADSBSharp plane tracking program working. I played with ADSB program for several days (couple of weeks). In just under 3 weeks from getting the SDR, I captured data from it. The next day, I did a FFT the SDR data. 5. Spectrally analyzing the captured data As previously mentioned, whether a FM radio station signal or a galactic hydrogen doppler signal, both have a spectrum. Thus, a FM radio station was used to simulate the galactic hydrogen doppler signal for testing purposes. The SDR data just captured can be converted to a spectrum using a FFT program. FFT programs are available on the internet. You just need some program that will run it. I have a Windows 7 x64 laptop, but I have an XP mode emulator which allows me to run old XP software. A free visual basic program for Windows 7 can be downloaded from Microsoft. Such a program could be used to convert the SDR data and do a FFT. I have downloaded such a free program, but have not gotten around to using it yet. In addition, Python has several scientific routines which can be called. Python could probably be used to extract data from the SDR, rather than the clumsy manual way we extracted data using rtl_sdr. A free Python program can be downloaded, and I have done that. I had good intentions, but I have not got around to learning how to use it. Python is similar to the C programming language. 5.1 Performing the FFT I used a 4K point FFT to obtain the frequency spectrum of the FM music station. One just separates the complex (I and the Q) data and processes it with the FFT. You can read the first number (I) and toss the second number (Q) away, then process it in the FFT. In that case, the I data would be put in the real input and zero into the imaginary input. Or one could use the complex data and do a complex FFT. It might be advisable to let the SDR settle down before using the FFT on the data. To do that toss away a multiple of 2 (because it is complex data) bytes of the first part of the data stream. For example, read two thousand bytes of data, but ignore it. That would be 1000 pairs of complex data. After that, read the data into the algorithm input array and compute the spectrum. From reading about processing a real galactic hydrogen doppler signal, several FFTs are averaged because the hydrogen doppler signal is weak (low). I read the SARA google group often and sometimes search past posts [12]. That reference also contain a web reference that lists the SARA Journal article titles. That is an excellent search aid to the SARA Journals.

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Before we plot the FFT output data using a spread sheet program, we have to scale the spreadsheet frequency axis. Two values are needed to determine the output FFT bin size: 1. the sampling rate (which we told rtl_sdr to sample at and 2. the FFT size we used to analyze the signal. Using those two values, we calculate the bin size (for the graph): Bin size = (sampling rate/2) / (FFT size / 2) = (2.4 MHz / 2) / (4096 / 2) = 585.9 Hz/bin. The output of the FFT is the bin number and the FFT value. Thus, full scale on the FFT chart is bin size multiplied by the half FFT size. Full scale on the FFT frequency axis now is 1.2 MHz which is half the sample rate. This illustrates the Nyquist-Shannon sampling theorem. If you do not sample at twice the highest frequency, you will get aliasing (fold over). Aliasing is why wagon wheels in old western movies appear to move backwards. We multiply the bin size by the bin number and use it for the x axis as frequency. The FFT power spectrum value is plotted on the y axis. The FFT is shown in Figure 9. Remember that a FM music radio station is modulated by frequency deviation (FM) as opposed to amplitude modulation (AM). FM modulation for US FM stations is normally under 200 KHz [13]. Notice from the graph that this particular FFT shows a frequency deviation of 85 KHz. Also notice another little spectral “bump” to the right of the main signal. Various “data” are often a part of the FM transmission (like title of song, radio station identification, or even background music). I went to that “bump” and could hear digital data (no music). For a galactic hydrogen signal, one would use 2.0 MHz sample rate rather than the 2.4 MHz sampling rate. (I have read that sampling at 2.0 MHz with this SDR is more reliable than at 2.4 GHz. Unfortunately I do not remember where I found that information.)

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Figure 9. 4K FFT of the captured data In summary, we have shown how to select a SDR, use it, get data out of it, and convert that data into spectrum data with a FFT. A FM radio station signal simulated a galactic hydrogen doppler shift signal, since the RF front end has not been built. This part of the 1.4 GHz radio telescope will work, so the RF front end to the SDR can be built. Part two will describe the RF front end and will present data obtained from the radio telescope. This ends part 1 of the 1.4 GHz radio telescope project. Now, I could order the RF front end parts and build the antenna. Since I had previously built a 1.4 GHz helical antenna, I would build a better helical antenna for part 2. I plan to build a horn and reflector antenna for later use with the system. Also, I decided to list a few of the many PDF files that I found on the internet. Appendix 6 contains that list, but I did not list any of the many websites that I looked at. As a last comment, I found that researching the SDR was more difficult than using it. Appendices Appendix 1. SDR# installations for Windows 1. Go to http://www.rtl-sdr.com/rtl-sdr-quick-start-guide/ 2. Go to “SDR# (SDRSharp) Set Up Guide (Tested on Windows Vista/7 + XP)” step2 and open the web link in another web page. 3. Download that zipped file. I created a SDR folder in my download files to download it into. In step 4, I extracted the zipped file in the SDR folder. 4. Run install in that unzipped folder. A window will open on the screen. Your antivirus may try to stop the download. Allow the download. The window will display several lines. When the window says “Press any key to continue . . .” then depress a key and the window will disappear. Sdrsharp will be a new directory. 5. Continue with the instructions on web site in step 2. When you get to step 6 you plug the SDR dongle in the USB connector. (I first plugged in the monopole antenna into the dongle). Wait for the system plug and play to tell you the dongle is ready. Be sure to follow the instructions and install the zadig driver. Continue with the rest of the instructions. Appendix 2. Hints for the installation: 1. Make note of the directory that the software is downloading to. I used the download directory to download the zip file. Then, when I unzipped the zip file, it used the same directory (download) to download the SDRSharp software 2. Be patient and wait for steps to complete 3. Do not plug in the dongle until the instructions tell you to 4. Before I plugged in the dongle, I carefully connected the antenna connection to the dongle by pushing it in until it clicked. No screwing was required, Also, even though I had an ESD protected front end, I kept one finger on the outside metal USB connector, as I connected the antenna, just to be safe.) 5. Wait for dongle to install before continuing. Appendix 3. Using the SDR after installing SDRSharp 1. Power up laptop normally 2. Plug the dongle into the same USB port every time (or it will not work) and wait for it to come on (blue light and sound of laptop recognizing USB device). I leave the antenna connected to the dongle. 3. Go to the directory where your SDRSharp software downloaded and click on blue SDRSharp application (SDRSharp.exe) as shown (highlighted) in Figure 3. 3. Click on play button

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4. The spectrum will be on the top of the display and the waterfall on the lower part. 5. Click on the upper number and enter the frequency and use the mouse to click on a “spectrum” bump. You will have to select the demodulation for the frequency you are turning to. For example, if it is a US FM station, select WFM (Wide FM) or if a US weather station select NFM (Narrow FM). 6. Plug the SDR into the same USB connector that you used to install the SDR# program. 7. I eject the SDR dongle when I am finished using it. Appendix 4. Downloading the program to read data from the SDR and use it 1. Download RelWithDebInfo.zip and unzip it. I used the download directory and unzipped it into that directory. 2. Go to that directory and find rtl-sdr-rlease folder. Go down to x32 folder and verify that there is a file named rtl_sdr.exe. (If you double click on rtl_sdr.exe a window will come up and quickly close. To use that file, we have to use the command prompt which is like the old DOS commands. (I have windows 7 x64 and x32 directory worked for me.) 3. Open a command prompt (click on Windows start button in lower left screen corner and type command prompt at the bottom of the window. When command prompt comes up double click on it. 4. Navigate to the download file. (For example, type dir and look for “RelWithDebInfo.zip” directory. Type cd “r*) and locate RelWithDebInfo directory (it is the unzipped directory). Continue going down until you get to the x32 directory.) If you need to back up type .. and depress carriage return. 5. After you have gotten to the x32 directory type rtl_sdr (and carriage return). You will get a display of rtl_sdr commands. 6. At this point install your SDR with antenna. You will get a USB ding and the SDR blue LED light will come. 7. Carefully type the following command and depress carriage return: > rtl_sdr -s 2400000 -f 88500000 capture.bin (Explanation, this tunes the SDR to 88.5Mhz and sets the sample rate to 2.4Mhz. This command captures data and stores it into the file capture.bin. Bin just stands for binary. It could be “dat” for data file.) 8. To stop the data capture, type the control key and the c key at the same time. Warning, the file will grow very quickly. 9. To exit the command prompt window type exit and depress the carriage return. Appendix 5. BASIC program to convert binary file to an American Standard Code for Information Interchange (ASCII) text file OPEN "input file name goes here" FOR BINARY AS #1 OPEN "output file name goes here" FOR OUTPUT AS #2 DIM a AS STRING * 1 WHILE NOT EOF(1) GET #1, , a ‘ read one character at a time x = ASC(a) ‘ convert the binary data to ASCII (readable data) PRINT #2, x ‘ store data in output file WEND CLOSE #1 CLOSE #2 END Appendix 6. The following files are a list of the more interesting PDF files that I found on the internet during the literature search. I did not include the many web pages that I looked at. They are not in any particular order.

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Some incomplete and brief comments are noted after each entry. I was aware of Marcus Leech and Dr. David Morgan before I started the SDR search. They do good work. 1. SDR equivalents to analog functions in a small-scale radio telescope by Marcus Leech http://www.sbrac.org/files/sdr_vs_analog.pdf Good overview. Discusses analog and digital spectrometer 2. A Software-Defined Radio for the Masses, Part 1 By Gerald Youngblood, AC5OG https://www.arrl.org/files/file/Technology/tis/info/pdf/020708qex013.pdf Very high level overview (no specific SDRs). 3. Some Measurements on DVB-T Dongles with E4000 and R820T Tuners: Image Rejection, Internal Signals, Sensitivity, Overload, 1dB Compression, Intermodulation http://f6fvy.free.fr/rtl_sdr/Some_Measurements_on_E4000_and_R820_Tuners.pdf August 2013 HB9AJG Good. Has some on E4000 and R820 front ends for the RTL SDR (our front end was the R820T). 4. Ultra Low-Cost Software-Defined Radio: A Mobile Studio for Teaching Digital Signal Processing http://www.asee.org/public/conferences/32/papers/10633/view click on view in upper right. Dr. Cory J. Prust (PrustHollandKelnhofer_ASee2014_SDR_FinalPaper.pdf) Discusses $700 to $1700 SDRs then gets to the SDR used in this paper (page 6). Has some on GNU, but is about courses taught. 5. Experiments with a Software Defined Radio Telescope http://www.dmradas.co.uk/new%20files%20dec%202011/RAG%20site%20pdfs/An_SDR_Radio_Telescope.pdf By Dr. David Morgan 2011 (An_SDR_Radio_Telescope.pdf) Uses the FUNcube dongle SDR 6. Welcome to the $20 SDR Receiver_UPDATED 3_2013.pdf http://www.qsl.net/4/4x1zq/4all/ham/Welcome%20to%20the%20$20%20SDR%20Receiver_UPDATED%203_2013.pdf 4Xida 2011. A presentation but good overview. 7. R820T Preliminary version of Rafael spec sheet (tuner used in the SDR described in this paper). http://superkuh.com/gnuradio/R820T_datasheet-Non_R-20111130_unlocked.pdf 8. ECE 4670 Spring 2014 Lab 6 Software Defined Radio and the RTL-SDR USB Dongle (lab6.pdf) http://www.eas.uccs.edu/wickert/ece4670/lecture_notes/lab6.pdf Has good overview of RTS-SDR USB dongle R820T. It has a picture of RTL SDR R820T without the cover on page 6 that is like the SDR used in this paper. 9. Rtl-sdr Tuning USD 20 Realtek DVB-T receiver into a SDR by Harald Welte. (rtl-sdr2.pdf) http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CB4QFjAA&url=http%3A%2F%2Fsdr.osmocom.org%2Ftrac%2Fraw-attachment%2Fwiki%2Frtl-sdr%2Frtl-sdr.2.pdf&ei=cCoGVd7KD-y1sASl2oKAAQ&usg=AFQjCNE1Jqsr3WmImDOY1SxXc0bKsEIOSA&bvm=bv.88198703,d.cGU A presentation. FUNcube dongle SDR and OsmoSDR (2012) 14 bit, RTL2832U based DVB-T. Talks about Gnuradio architecture. References [1] SARA July-August 2012, pages 63- 67, Using a Small Antenna to Detect the Neutral Hydrogen Line, Jan Lustrup. [2] The Radio Astronomy Handbook Fourth Edition 1992-1993, pages 173-177, out of print, Op Amp Filter/Detector Scan Board, Robert Sickels. [3] http://en.wikipedia.org/wiki/Software-defined_radio [4] http://rtlsdr.org/#history_and_discovery_of_rtlsdr [5] http://sdr.osmocom.org/trac/wiki/rtl-sdr [6] SARA Aug 2013, pages 38- 46, Low Cost Hydrogen Line Radio ￡160 using the RTL SDR, Peter East. [7] http://www.sbrac.org/files/budget_radio_telescope.pdf A 21cm Radio Telescope for the Cost-Conscious, Marcus Leech [8] The RF front end hardware needed for a 1.4 GHz system would be an antenna (dish, horn, yagi, or helical), Low Noise Amplifier (LNA), and a band pass filter. Depending on the antenna gain, a cheap in line satellite type amplifier might be needed after the LNA. I have thought that I might try a satellite finder initially for the band pass filter. While the satellite finder’s bandwidth is wide, the SDR has an adjustable filter which may work. If it

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works, I will try it without the satellite finder. If it does not work, I will I will buy a band pass filter or build a 1420 MHz interdigital band pass filter. Buying a filter would be simpler because I would need a signal generator to adjust the filter. [9] http://www.rtl-sdr.com/tag/meteor-scatter/ describes using the RTL SDR to detect meteors. [10] In interferometry the inverse FFT is used on a complex signal to obtain position. The SDR complex signal is not the same as normal interferometers (where the I signal comes from one antenna and the Q signal from another antenna). However, http://www.superkuh.com/rtlsdrinterferometer.html explains an intensity interferometer that sums both antennas and is fed into a RTL SDR. That article states "A special case of the interferometer is the intensity interferometer, which performs an intensity correlation of signals from the two detectors. Although in the intensity interferometer the phase information from the two antennas is discarded, the correlation of the two signals remains useful. Aperture synthesis is not practical, but some important source characteristics may be determined." Aperture synthesis is using the inverse FFT to get position of the source in the sky. Also, notice that article states that the phase information is thrown away. I know that two different LNBFs with incoherent oscillators would be a problem, but I suppose that two incoherent oscillators would produce some kind of beat frequency. Notice that the SDR in the picture is shown “wrapped in aluminum tape” (search the website for that phrase). That is obviously a homemade Faraday shield to reduce noise. Also notice that the RTL SDR has the e4k tuner which is an improved version of the e4000. It is not the tuner that is described in this article. More interferometer information is found at http://www.sbrac.org/files/DTP_RX.pdf RTLSDR-based, Software Defined Radio Alternative to Switched Radiometers for Continuum Radio Astronomy by Ken Tapping and Marcus Leech. A standard Dicke radiometer and a “RTLSDR dongle+Gnu Radio Version” Dicke radiometer are discussed in section 2. Section 3 discusses a standard phase switched interferometer and a “RTLSDR dongle+Gnu Radio Version” phase switched interferometer. Both of the SDRs in the above references use Linux and GNU. [11] http://en.wikipedia.org/wiki/Automatic_dependent_surveillance_%E2%80%93_broadcast [12] https://groups.google.com/forum/#!forum/sara-list. Also, a list to SARA articles is found at: https://drive.google.com/file/d/0B3WMi2fu54AMRnRQbWFkX0NFZ3M/edit?pli=1 [13] http://en.wikipedia.org/wiki/FM_broadcast_band

Kenneth Kornstett holds a Masters of Physics degree from the University of Tennessee. He has worked in various technical and engineering jobs for various companies in the US and overseas. He once taught several three day microprocessor seminars in major cities across the US in the 70s. He can be contacted at kennethk_us@yahoo.com. Please put “SDR” in the subject line.

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GPS Network Time Server on Raspberry Pi :GpsNtp—Pi Whitham D. Reeve

1. Introduction This article describes an application of the Raspberry Pi, or RPi, as a network time server. A network time server determines the time from an accurate reference clock and distributes this time to clients on a local area network (LAN) or a wide area network (WAN) such as the internet. The clients typically are ordinary PCs used in radio astronomy observations. The RPi hardware and software is combined with the Network Time Protocol and a Global Navigation Satellite System receiver to produce a high performance device. In the following sections I provide descriptions of the protocols, reference clocks and hardware requirements as well as statistical analyses of two RPi network time server systems. A companion document, GpsNtp-Pi Time Server Installation and Operation Guide {GpsNtp-Pi}, provides detailed setup instructions.

Figure 1 ~ GpsNtp-Pi time server block diagram. The server’s main functional components are the Raspberry Pi platform and GNSS (or GPS) receiver on the left. The time server can be provisioned and used through a wired or wireless network connection and can serve time to clients on the LAN or WAN. It also can work with external time servers. The Global Navigation Satellite System, or GNSS, is most often simply called GPS after the original Global Positioning System deployed by the US government; however, GNSS includes navigation satellites and systems by other countries. By their very nature these systems provide very high time accuracy to receivers, which can

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Note: Internet links in braces { } and references in brackets [ ] are provided in section 9.

Abbreviations: GNSS; Global Navigation Satellite System GPIO: General Purpose Input-Output GPS: Global Positioning System GPSD: GPS Daemon LAN: Local Area Network NMEA: National Marine Electronics Association NTP: Network Time Protocol NTPD: NTP Daemon PC: Personal Computer PPS: Pulse Per Second RPi: Raspberry Pi USD: US Dollar UT: Universal Time UTC: Coordinated Universal Time WAN: Wide Area Network WLAN: Wireless LAN

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then produce reference clocks for a network time server. The Network Time Protocol, or NTP, is the most common protocol for exchanging time information over a network. It is used to synchronize and accurately maintain time-of-day clocks in PCs and larger computer systems (figure 1). As described here, the GpsNtp-Pi network time server total cost is about 100 USD. This system can operate as a standalone NTP time server. Standalone in this context means the GpsNtp-Pi has no connection to any other NTP server; it is not an autonomous time server because it relies on reception of GNSS signals. The GpsNtp-Pi also can be used in conjunction with other local NTP servers or a pool of remote NTP servers to improve overall performance and reliability (the remote NTP servers do not have to be based on RPi technology). The system meets the needs of many radio astronomy applications where there is the need for accurate time stamps on radio observations produced on a PC. In the GNSS and NTP environments, all times are in Coordinated Universal Time (UTC). The GpsNtp-Pi does not have a holdover clock, so a failure of the GPS receiver or loss of satellite reception results in time server failure. I claim no originality for the concept of combining the Raspberry Pi with a GPS receiver. However, I have introduced a number of enhancements compared to the NTP server projects described on internet websites. In particular, the standalone operation described here is not described in any useful detail anywhere else. Also, I have provided specific installation and provisioning details that I had to determine through considerable research, lengthy testing and trial and error. Many NTP server projects found online perpetuate provisioning mistakes and errors from other projects, and some online information and setups are just plain wrong. The project described here corrects those mistakes or avoids them altogether. This project follows two of my previous RPi projects, LWA TV {LWATV) and Callisto-Pi (ReeveCPi). RPi hardware descriptions as well as brief overviews are given there.

2. Network Time Protocol Network Time Protocol is a set of procedures used by computers and PCs to exchange time information and then to compensate for the relative inaccuracy of a PC’s real-time (or time-of-day) clock. NTP is run as a background process or daemon. The underlying software is called NTP daemon or just NTPD. The software currently is version 4 (NTPv4), and it as well as tutorials and configuration information can be downloaded from the NTP website {NTPOrg}. NTPD can operate as a time client or server, and it always uses Coordinated Universal Time (UTC). When installed as a client on a PC it synchronizes and regulates the PC clock by periodically obtaining time information from an external NTP server, either on the same LAN or over the internet (WAN). NTP can use a reference clock, which is a clock that obtains accurate time information from an external source such as a GPS receiver or atomic clock. NTP cannot operate on a client PC unless it has at least one source of time information, either a reference clock or the URL or IP address of an NTP server. Most PCs operate as NTP clients, typically by running a free software application such as SymmTime, Dimension4 or Meinberg NTP. Many other clients will be revealed by an internet search.

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There may be considerable variability in the networks between NTP clients and servers, leading to variable delays in synchronization messages between a network time server and a client PC. NTPD’s job is to monitor these delays in real time and then estimate what synchronization actions are needed at the client to reduce the difference between the PC’s clock time and the NTP server’s clock time. NTPD speeds up or slows down the PC’s clock until synchronization is achieved. NTPD has an ultimate precision of about 200 ps but PCs and most other computer systems cannot measure time to this resolution. Generally, after the PC’s clock is set, NTPD will maintain it within 128 ms even in the face of extreme network path congestion and jitter. NTPD slews the client’s clock in very small steps, effectively providing a continuous timescale. The maximum slew rate under most conditions is limited to 500 parts per million. A simple calculation shows that the maximum slew rate is 2000 s for each 1 s error. An overall goal of using NTP on a PC is to maintain the clock offset from UTC to ≤ 100 ms. This means that the polling and correction interval by the PC’s NTP client cannot be too long. For example, if the PC’s clock drifts 250 ms/h (equivalent to 6 s/day) and the NTP polling interval is 24 h, the goal never will be achieved. Windows PCs that have the built-in Internet Time feature enabled use a 7 day update interval by default, much too long to be of any use in radio observations. On the other hand, a polling interval that is too short usually serves no useful purpose, increasing network load and potentially manifesting as clock instability. I have found that the best interval is between 15 min and 2 h for most PCs. Generally, the shorter interval is used on PCs subject to considerable short-term temperature variations and longer interval for PCs in stable environments. It should be noted that PCs running many CPU-intensive processes throughout the day will experience higher internal temperature variations and thus larger clock variations even though they may be in a stable ambient environment. The NTPD handles leap seconds very easily and procedures are included in the installation guide so that it automatically implements a leap second when the time comes. A leap second is added or subtracted every so often to keep Universal Time (UT, in particular, UT1) and Coordinated Universal Time (UTC) synchronized within less than ±0.9 second. The UT time scale is based on Earth’s rotation rate. Embedded in UT is the mean astronomical second, which is defined as 1/86 400 of the mean solar day as determined by precise measurements. On the other hand, UTC is an atomic time scale based on the emissions frequency of cesium atoms when certain electrons change state. Embedded in UTC is the definition of the second, which is 9 192 631 770 periods (a frequency of about 9.193 GHz) of the radiation emitted from cesium 133 when it is in a specific environment. As of this writing (February 2015), the most recent leap second was added at the end of June 2012 and another one is scheduled to be added at end of June 2015 (see {RvTime}).

3. Time Sources and Reference Clocks In the NTP server described here, two reference clocks are used, both obtained from the GPS receiver. The first is a series of pulses on one of the receiver output pins. These pulses very accurately indicate the start of a UTC second and are called pulse-per-second or PPS. The PPS signal is a simple pulse train

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(figure 2) aligned within 10 to 30 ns of the start of a second depending on the receiver. The PPS is used in in this RPi implementation in a kernel-mode process, which is more accurate than the alternately available shared memory process. The kernel-mode PPS is capable of maintaining the server time to within ±1 μs. Clock measurements are described in section 8. The second reference clock is the data output by the GPS receiver on its serial port. All GPS receivers provide time and date, and this data is used to establish a coarse time setting by removing the ambiguity inherent to the PPS. The PPS marks the beginning of a second and the serial data immediately follows with the date and time information in the NMEA sentence format {NMEA}. This data is subject to variations because it is sent from the receiver to the RPi over an asynchronous serial data port and time is required to parse and derive the needed information. My measurements indicate the resulting offset is 534 ms for one receiver and 125 ms for the other receiver in my lab test systems.

Figure 2 ~ Left: PPS pulse measurements show the 1 s pulse period (1 Hz frequency). Right: Pulse-width measurements using the oscilloscope cursors indicate 100 ms pulse width (0.1 or 10% duty cycle).

The NMEA sentence formats are well documented. Below is an example of the GNRMC data block taken 15 February 2015 from one of the GpsNtp-Pi lab test systems. Navigation and time data such as these are viewable with software tools on the RPi console through the GPS daemon program GPSD. $GNRMC,170554.00,A,6111.95839,N,14957.38320,W,0.024,,150215,,,D*72\x0d\x0a Where: GN Mixed GPS and GLONASS satellite data (GP would be GPS only) RMC Recommended Minimum navigational data using sentence C 170554.00 Time of fix: 17:05:54.00 UTC A Status: A=Active or V=Void. 6111.95839,N Latitude in ddmm.mmmmm, N/S: 61° 11.95839' N 14957.38320,W Longitude in ddmm.mmmmm, E/W: 149° 57.38320' W 0.024 Speed over the ground in knots: 0.024 (receiver was at rest) ,, Track angle in degrees true: null value shown (receiver was at rest) 150215 Date: 15 February 2015 ,,, Magnetic variation in degrees, E or W: null values shown D FAA mode indicator: A=autonomous, D=differential

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*72 Checksum: beginning with * \x0d\x0a Carriage return (CR)\Line feed (LF) in hex In operation, the RPi NTP server obtains coarse time by decoding the NMEA data and then refines the time with the PPS output signal. In this standalone mode, the NTP server needs no connection to any other time source or reference clock. The RPi platform itself does not have a built-in real-time clock or any kind of holdover clock and requires an external source (GPS receiver) for this information.

4. GPS Receivers I built two NTP servers with different GPS receivers (figure 3). The first is a GlobalTop Technology (GTop) FGPMMOPA6H standalone GPS module, which is based on the MediaTek MT3339 GPS chipset. The module can use its built-in patch antenna or an external active antenna with automatic switching when the external antenna is connected. The GPS receiver supplies the high accuracy PPS on an output pin after it has obtained a 3-dimensional position fix. The receiver also includes a bidirectional serial port for sending NMEA position, time and date data to the RPi and receiving control data (the control function is not needed in this implementation). The GPS receiver with internal patch antenna is a small surface mount device, about 16 x 16 x 3 mm.

Figure 3 ~ GPS receivers installed on the RPi platform. Left: The Adafruit board is shown with a WLAN USB dongle installed (black object on far-left). The GPS board has a prototyping area that may be used for additional circuits. The GPS receiver chip, which has a built-in patch antenna, is on the right-middle of the board and the battery is directly above it. Right: The HAB Supplies board uses a larger battery and the receiver is in the upper-right corner just below the SMA antenna connector. This receiver is smaller because it does not have a built-in antenna. The GTop receiver is available from Adafruit {GPSHat} already mounted on an RPi compatible printed circuit board with an EEPROM integrated circuit (not used), battery holder, fix indicating LED, connector and a few passive components. The battery provides backup for the receiver’s real-time clock and configuration settings. The PCB is installed as a daughterboard on the RPi and called a Hat by Adafruit. It connects to the GPIO connector on the RPi, which supplies 3.3 Vdc to the receiver and has connections for the serial port and PPS.

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The second GPS receiver is the uBlox Max M8Q {uBLOX}. This receiver is functionally similar to the GTop unit above but the module is smaller at 10 x 10 x 3 mm and it requires an external active antenna. It is supplied already mounted on a PCB with battery holder, connector and other components, but no EEPROM, by HAB Supplies {GPSHAB}. As with the Adafruit unit, the HAB board installs as a daughterboard and receives power from the RPi. Both receivers have a real-time clock (RTC) that can operate from a battery backup when power is removed. The battery backup retains this data in RAM to improve satellite acquisition time when power is restored. This is called a warm-start or hot-start depending on the length of the power loss. A cold-start is when the receiver has no previous data in RAM and power is applied. In my tests, warm-starts typically required < 1 min even when the antennas did not have a clear view of the sky. Hot-starts typically required a few seconds. The cold-start sensitivity of both receivers is worse than after satellite acquisition is completed and the receiver transitions to tracking mode. When in tracking mode the sensitivity improves by about 20 dB. Both receivers can concurrently receive GPS and GLONASS satellites in 66 channels (GTop) or 72 channels (uBlox), and the uBlox receiver also can receive the BeiDou satellites. Both receivers have an onboard RF connector for an external active antenna. The Adafruit board uses a tiny U.FL (male) connector and the HAB Supplies board uses an SMA (female). Both connectors and their PCB attachments are relatively fragile (especially so for the tiny U.FL connector) and thus require a flexible pigtail or jumper for connection to the main antenna cable to relieve mechanical stress. The U.FL connector on the Adafruit Hat is not designed for routine connection and disconnection and is rated for only 30 connect/disconnect cycles. The GPS receivers use the L1 band at about 1575 MHz. At this frequency coaxial cable loss can be significant if the cable is long, nullifying the gain of an active antenna. During tests, I had very good results by simply placing the RPi with GPS daughterboard (Adafruit) or the active antenna (HAB Supplies) near a window. I also found that both receivers can acquire satellites when in my lab, which is on the lower level with no windows that have a clear view of the sky (trees and interior walls obstruct the view). I did additional tests on the GTop receiver with its built-in antenna. While it was sitting on a north-facing windowsill (worst case for satellite view) and in tracking mode, I placed a sheet of insulated aluminum foil over the entire RPi assembly for several hours with no obvious ill-effects. I also placed it in a cardboard box with no problems. The only way I could prevent GPS lock was to place a small kitchen LCD television within about 30 cm and turn the TV on. The RFI from the TV definitely caused satellite acquisition problems. Overall, I found the GTop receiver to be a slightly better than the U-Blox receiver in the NTP server application in terms of clock offsets, but both receivers are adequate.

5. System Packaging In a practical application, the RPi platform with GNSS receiver would be packaged in a metal enclosure to provide mechanical protection. In such a setup, the GTop receiver would have to be used with an external

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antenna. In one of my prototype systems, I used an extruded aluminum enclosure and a small 5 W dc-dc converter, input power filter and a few other components (figure 4).

Figure 4 ~ Upper-left: GpsNtp-Pi system prototype packaged in an extruded aluminum enclosure 162 x 105 x 57 mm (external antenna not shown) with a dc-dc converter. A WLAN dongle can be seen in a USB port. Upper-right: The rear panel has a 2.1 x 5.5 mm dc power jack, power switch and power LED. Lower-left: The RPi is mounted on 6 mm standoffs and an adapter cable connects the Adafruit GPS receiver board to an SMA-F panel connector. Lower-right: A dc-dc converter converts the nominal 9...15 Vdc input to 5 Vdc for the RPi and is mounted on a small printed circuit card with a Pi input EMI filter and polarity guard diode. The RPi board supplies 3.3 Vdc to the receiver.

6. Standalone Operation The GpsNtp-Pi can be operated as a standalone time server or in conjunction with other time servers on the LAN or WAN. Time servers have the best accuracy and performance when operated in a peering arrangement in which the ensemble time typically is better than the time produced by any one server. However, there may be situations where a single, or standalone, time server is the only practical setup (figure 5). This would be useful in installations that do not have access to other time servers on the same LAN or via the internet or there is a need to minimize internet traffic.

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During development of this project, attaining true standalone operation of the GpsNtp-Pi was problematic. In particular, I found that if the power was removed from the RPi and GPS receiver for more than about 4 hours, the NTP protocol would not synchronize with the GPSD shared memory data and PPS. The GPS receiver real-time clocks have a battery backup and continue running after power removal. When repowered the current time is used to start the synchronization process, but this was not happening. Through a series of lengthy tests, I traced this to the default settings in the shared memory driver for the GPS serial data. After changing the default, the system will acquire and track the correct time within a few minutes after power is reapplied regardless of the outage length.

Figure 5 ~ In the standalone mode, the GpsNtp-Pi time server is operated without network connections to any other time server but still can serve time over the LAN or WAN.

7. Hardware and Software Hardware: This project was developed on an unmodified Raspberry Pi model B+. It most likely will work on the model B but has not been tested. The RPi is operated “headless”; that is, it is used without a directly connected keyboard, mouse or monitor. All provisioning is done from a PC running a Secure Shell (SSH) terminal program and connected to the same LAN as the RPi. The hardware requirements are minimal and costs are low (table 1).

Table 1 ~ Hardware Requirements and Costs

Item Adafruit HAB Supplies

Base system Raspberry Pi B+, 35 USD Raspberry Pi B+, 35 USD

GPS receiver assembly Ultimate GPS Hat for Raspberry Pi {GPSHat}, 45 USD

Raspberry Pi+ GPS Expansion Board {GPSHAB}, 70 USD

External active antenna Optional, 13 USD Required, 15 USD Internal patch antenna Yes No Soldering required Yes Yes Mounting hardware required Yes Yes

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RPi power supply 5 Vdc 10 W 5 Vdc 10 W Software: The system uses the Raspbian distribution, which is a version of Linux. Although the software includes NTPD it must be recompiled to include PPS support. GPSD also must be installed. All programs and applications may be freely downloaded from the internet, and installation details are provided in the setup guide.

8. Performance Measurements The time domain quality of a clock is specified by its accuracy and stability, where accuracy indicates how close the clock time is to UTC and stability indicates how well it maintains a constant time interval (for example, 1 s). Clock measurements are made at regular intervals and then used to compute statistical variances – Allan Variance (AVAR), Modified Allan Variance (MVAR) and Allan Time Variance (TVAR) or their square roots Allan Deviation (ADEV), Modified Allan Deviation (MDEV) and Allan Time Deviation (TDEV) – over various averaging intervals. I used NTPD’s built-in statistics logs and the Alavar software application to perform the computations {Alavar}. The PPS reference clock and associated processing determines the overall stability of the GpsNtp-Pi time server with respect to UTC. Measurements were made using a flag in the PPS software driver that provides a time stamp for each PPS. First, the time server was operated in standalone mode for at least 24 hours to allow NTP synchronization to stabilize. The flag then was set and the server run for another 24 hours to gather the offset data (specifically, the clockstats parameter). One system was operated in standalone mode and the other in pooled mode to provide comparative measurements. The Adafruit system with GTop receiver was setup in standalone mode to use its built-in antenna and a wireless network connection, and the HAB Supplies system with uBlox receiver was setup in pooled mode to use an inexpensive external patch antenna and a wired network connection. In all measurement setups, the systems were placed on or near the sill of a north-facing window, which perhaps is a worst-case scenario for measuring performance under poor operating conditions. The network connection type does not affect system performance when in standalone mode (no network connection is needed) but can affect operation in pooled mode because the time messages from external servers are sent and received in a variable network transmission environment. It should be noted that the network connection type can affect the time stability of an NTP client. During my measurements, the ambient temperature near a window varied throughout the day and night, but I made no measurements of the range. Both systems show a small offset from perfect synchronization with UTC as indicated by the basic data in Table 2 and the TDEV plots, which have an average slope of about 1 μs/s [figure 6(a) and (b)]. Most of the offset likely is due to the processing time within the RPi platform. If there had been no offset, the TDEV plots would have zero slopes. The clock stability indicated by the Allan Deviation (ADEV) is approximately 1.0 to 1.5 μs. Much of this probably is due to the environment but processing variations in the RPi also have an effect. The ADEV plots for perfectly stable clocks would be straight horizontal lines (zero slopes). The original data [figure 7(a) and (b)] shows some systematic variations, which are discussed below.

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The TDEV and ADEV measurements are several orders of magnitude worse than atomic clocks, which typically have 0.02 to 0.5 ns accuracy and 30 to 50 ps stability, or even good oven-controlled crystal oscillators (OCXO). An oven-controlled oscillator typically has 10 ns accuracy and 1 ps stability. High-performance clocks usually include an OCXO for short-term stability and a cesium or rubidium atomic oscillator for long-term stability. Rubidium clocks often are disciplined by a GNSS receiver to reduce effects of aging and drift. The GpsNtp-Pi uses a GNSS receiver, which provides accuracy traceable to an ensemble of atomic clocks, but it does not have a crystal oscillator to improve its short-term performance. Nevertheless, the GpsNtp-Pi performance is quite remarkable considering its simplicity and cost.

Table 2 ~ GpsNtp-Pi Statistics

System Receiver

Average offset (s)

Standard deviation (s) ADEV slope

Stability (ADEV at τ = 1 s)

Remarks

GTop 77.318 10−− ⋅ 65.928 10−⋅ 0.099 61.107 10−⋅ Standalone, wireless network uBlox 73.376 10−− ⋅ 64.651 10−⋅ –0.000132 61.589 10−⋅ Pooled, wired network

Figure 6(a) ~ TDEV (blue trace) and ADEV (red trace) with error bars for GpsNtp-Pi based on Adafruit board with GTop receiver. Standalone mode with 1 s sampling interval (τ = 1 s). The TDEV plot indicates some variation in offset for various averaging times. The ADEV plot shows that the stability is the best when the variance is calculated with an averaging time of approximately 17 s and is the worst at 1000 s.

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Figure 6(b) ~ TDEV (blue trace) and ADEV (red trace) with error bars for GpsNtp-Pi based on HAB Supplies board with uBlox receiver. Pooled mode with 1 s sampling interval (τ = 1 s). The TDEV plot shows a slightly more constant offset than the GTop receiver system. The ADEV plot shows that the stability is the best when the variance is calculated with an averaging time of approximately 67 s and is the worst at 17 s.

Figure 7(a) ~ Original data for GpsNtp-Pi based on Adafruit board with GTop receiver taken with 1 s sampling interval (τ = 1 s). The index is the sample number counted in sequence from the start time of 0000 UTC. The plot clearly shows systematic variations in the data, most likely caused by temperature variations. A setback thermostat engages at 0730 (index = 27 000 s) and disengages 7 h later (index = 50 000).

Figure 7(a) ~ Original data for GpsNtp-Pi based on HAB Supplies board with uBlox receiver taken with 1 s sampling interval (τ = 1 s) . The index is the sample number counted in sequence from the start time of 0000 UTC. The plot shows systematic data variations similar to 7(a) but of a different character.

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The oscillatory behavior of the data plots, particularly evident for the GTop receiver, most likely indicates a temperature influence on clock offset stability. At night the setback thermostat for the room lowers the temperature as seen by the well between about 27000 and 50000 points. Each point is 1 s and the data starts at 0000 UTC (1500 local time). The temperature starts to drop around 0700 UTC (2200 local) and begins to rise 7 h later. The HAB Supplies unit was farther from the baseboard heater and registered more rapid variations, possibly related to the faster sampling of the GPSD data on the uBlox receiver. Future work includes more measurements: A more complete characterization of the GpsNtp-Pi would entail a total of four measurements on each unit:

Measure each unit with and without a pool of time servers and wired and wireless network connections (it is expected that the network connection might affect only the measurements with a server pool and that a wireless connection will result in much higher time jitter)

It would be interesting to see if using an external antenna with the GTop receiver changes any of the results It would be useful to measure the units while in a temperature controlled enclosure (requiring external

antennas on both units) Measurements over periods longer than 24 h would be useful for demonstrating long-term stability (or

instability)

9. References, Web Links and Further Reading {Alavar} http://www.alamath.com/ {ReeveCPi} http://www.reeve.com/Documents/Articles%20Papers/Reeve_Callisto-Pi.pdf {GPSHAB} http://ava.upuaut.net/store/index.php?route=product/product&path=59_60&product_id=117 {GPSHat} https://blog.adafruit.com/2014/12/26/new-product-adafruit-ultimate-gps-hat-for-raspberry-pi-a-

or-b-mini-kit/ {GpsNtp-Pi} http://www.reeve.com/Documents/Articles%20Papers/Reeve_GpsNtp-Pi_Setup.pdf {GTOP} http://www.gtop-tech.com/en/product/LadyBird-1/MT3339_GPS_Module_04.html {LWATV} http://www.reeve.com/Documents/Articles%20Papers/Reeve_RPi-LWATV.pdf {NMEA} http://www.gpsinformation.org/dale/nmea.htm {NTPOrg} http://www.ntp.org {RvTime} http://www.reeve.com/Documents/Articles%20Papers/Reeve_LeapSec2015.pdf {uBLOX} http://www.u-blox.com/en/gps-modules/pvt-modules/max-m8-series-concurrent-gnss-

modules.html Acknowledgements: David J. Taylor worked with me to determine the proper settings in the ntp.conf file for standalone operation. His website at http://satsignal.eu/ntp/Raspberry-Pi-NTP.html includes many helpful details and includes performance charts for his own RPi time servers.

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Ken Redcap, right, answers a visitor’s question.

The Cold Never Bothered Me Anyway Ethan Siegel

For those of us in the northern hemisphere, winter brings long, cold nights, which are often excellent for sky watchers (so long as there's a way to keep warm!) But there's often an added bonus that comes along when conditions are just right: the polar lights, or the Aurora Borealis around the North Pole. Here on our world, a brilliant green light often appears for observers at high northern latitudes, with occasional, dimmer reds and even blues lighting up a clear night.

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Auroral overlay over Antarctica, from the IMAGE spacecraft. Image credit: NASA Earth Observatory (Goddard Space Flight Center) / Blue Marble team. We had always assumed that there was some connection between particles emitted from the Sun and the aurorae, as particularly intense displays were observed around three days after a solar storm occurred in the direction of Earth. Presumably, particles originating from the Sun—ionized electrons and atomic nuclei like protons and alpha particles—make up the vast majority of the solar wind and get funneled by the Earth's magnetic field into a circle around its magnetic poles. They're energetic enough to knock electrons off atoms and molecules at various layers in the upper atmosphere—particles like molecular nitrogen, oxygen and atomic hydrogen. And when the electrons fall back either onto the atoms or to lower energy levels, they emit light of varying but particular wavelengths—oxygen producing the most common green signature, with less common states of oxygen and hydrogen producing red and the occasional blue from nitrogen. But it wasn't until the 2000s that this picture was directly confirmed! NASA's Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) satellite (which ceased operations in December 2005) was able to find out

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how the magnetosphere responded to solar wind changes, how the plasmas were energized, transported and in some cases) lost, and many more properties of our magnetosphere. Planets without significant magnetic fields such as Venus and Mars have much smaller, weaker aurorae than we do, and gas giant planets like Saturn have aurorae that primarily shine in the ultraviolet rather than the visible. Nevertheless, the aurorae are a spectacular sight in the evening, particularly for observers in Alaska, Canada and the Scandinavian countries. But when a solar storm comes our way, keep your eyes towards the north at night; the views will be well worth braving the cold! Astronomy? Impossible to understand and madness to investigate.—Sophocles, c. 420 BCE Measuring the Milky Way angle (or how I got into radio astronomy) Kenneth Kornstett Abstract A simple inexpensive radio telescope was built using off the shelf components: a small TV satellite dish and a battery powered satellite finder. It was used with the sun to calculate the dish antenna beamwidth. After that, a data logger was built and the sidereal time was measured. As an afterthought, the angle of the Milky Way was calculated a couple of months later. 1. Introduction

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This project was done in 2008. The results were later an application note for a microcomputer company. Unfortunately, that paper has been deleted from the internet. The paper was rewritten with more radio astronomy detail and less microcomputer detail for the SARA Journal. The project will be described in three sections: 1) background (literature) search, 2) proof of concept, and 3) measurements of the Milky Way. 1.1 Literature search The radio astronomy background search began with just an idea. After building a simple VHF weather satellite receiving system, I thought about receiving RF signals from Jupiter, but the size of the HF antennas would interfere with mowing the grass. Next, I thought about the sun. Earlier I had built a simple field strength meter (FSM) with a homemade 2.4 GHz quad antenna with reflector. I could detect the sun by swinging the portable FSM across the sun, but it had a wide beamwidth antenna. I turned to the internet for sun data such as frequency ranges, signal levels, and ideas in general. In the process, I found a web site with two introductory radio astronomy books and ordered both [1]. While reading those books, I thought about a satellite TV dish antenna which was at a higher frequency than the FSM. The FSM quad antenna was wide beamwidth compared to a narrow beamwidth dish antenna. I found on the internet that gain is needed even for a narrow beam dish when observing the sun [2]. On another website I found that a 12 GHz TV satellite dish with a Low Noise Block Feedhorn (LNBF) and a satellite finder had been used to detect the sun. About that time, I got a free used satellite dish with LNBF [3]. I started looking and found a cheap satellite finder with a battery pack ($25 + shipping). Satellite TV installers use a satellite finder to point the satellite antenna. It connects to the LNBF and produces both an audio tone and a meter reading of the signal level. I decided to use it as an amplitude modulation (AM) detector [4]. The Milky Way would be large (angularly) compared with the sun, but I suspected that I might even be able to detect the Milky Way with it. At worst case, I could use a cheap inline satellite amplifier ($5). I decided to try without an amplifier first. At that point, I did a calculation and decided that the satellite dish and LNBF would work [5]. I now had a simple system to demonstrate proof of concept (detecting the sun). 2.0 Proof of Concept 2.1 Mounting the antenna I mounted the antenna using a homemade support attached to a deck post. I found a scrap piece of pipe to slide into the satellite antenna mounting hole. Figure 1 show the satellite antenna mounted on the deck. The LNBF is part of the satellite system and is positioned at the focus of the dish. The LNBF had three feedhorns which can be used to obtain three different satellites. I used the center feedhorn, but at first I connected to the wrong jack at the base of the LNBF. I found the correct jack from a picture on the internet. I would use the antenna in the drift mode where the antenna beam pointed south and the sky drifted past the beam. I would only change the antenna elevation. Thus, I would not need any antenna pointing electronics. It would be a simple and “dumb” system to experimentally detect the sun (proof of concept).

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Figure 1. Satellite antenna and LNBF mount The satellite finder and power pack are shown on the rail next to the antenna. Figure 2 shows the satellite finder and battery pack. Notice gain knob on front. I would keep the gain setting constant for each run (relative measurement).

Figure 2. Satellite finder and battery pack

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2.2 Observing the sun The first data was taken by pointing the antenna at where the sun would be at noon. I manually read and recorded the satellite finder analog meter (1 minute intervals). I plotted the data using a spreadsheet. The data curve was good; even though I started the data run a little late. The sun curve is shown in Figure 3. The curve axes are time and signal power (the satellite finder detector is acting as a square law detector). From that curve, the beamwidth of the antenna can be calculated. One just finds the half power points (from maximum peak to the baseline) and measures the time between those two points. The beamwidth was calculated to be 2.25 degrees from those two points [6]. The sun is 0.5 degrees so a lot of cold sky is in the background while the sun passes through the antenna beamwidth. Obtaining a good beamwidth curve was a good start, and I was surprised that it worked so well.

Figure 3. Antenna beamwidth curve

This test demonstrated that the system was working for a strong radio signal source like the sun. The next step was to build a data logger for remote monitoring. I did not want to have to write every reading on a piece of paper, so I designed and built a data logger shown in Figure 4 behind the laptop computer. The voltage from the satellite finder meter was buffered and amplified with cheap operational amplifiers, then digitized with an analog to digital converter (ADC) controlled by a microcomputer. The data was sent to the laptop, time stamped, and stored in a file. This 8 bit data logger circuit is part of a previous SARA article [7].

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Figure 4. Homemade data logger with power injector and satellite finder (I later upgraded the 8 bit ADC chip with a 12 bit ADC chip that was pin for pin compatible and only required one extra resistor and one extra capacitor. The microcomputer code was slightly changed.) I replaced the battery pack with a power injector that is shown on deck floor to the left of the laptop. I later built a homemade power source and injector to replace the power injector. (Power injector supplies power to the LNBF and satellite finder via the coax cable that carried the RF signal.) In summary of the proof of concept stage, the simple battery power system worked. The original battery system was less than $30 (satellite finder) in 2008, but the satellite dish and LNBF were free. The satellite dish and LNBF could cost up to a hundred dollars if purchased. The power injector was about $30 plus shipping, but I had all the parts for the data logger on hand. My other costs were for RG6 ordinary satellite TV coaxial cable. Now it was time to use the radio telescope. By the way, the LNBF (without the bulky dish) and battery pack can easily be taken to a school to demonstrate microwave detection of body heat, the sky, and the ground. Planck’s radiation law could be briefly discussed at the same time. 3. Measurements of the Milky Way 3.1 Sidereal time measurement With the data logger, I was now ready to perform some automated radio astronomy measurements. After detecting the galactic center, I made two consecutive measurements with the antenna pointed at the same elevation over a two day period. (Sidereal time is the reason constellations arise earlier each day.) The galactic center is near Sagittarius A (Right Ascension 17:46 and Declination -28:51). I turned the system on before the Milky Way came into the dish beamwidth, then later turned the system off. Figure 5 shows those two curves for the galactic center. The data samples were taken at one minute intervals. I initially tried 15 then 10 minutes sampling rates. The one minute sample rate allowed me to observe the sidereal time. Sidereal time is actually a little less than 4 minutes [8]. Notice the gradual upward baseline drift on the green curve. I suspected the detector in the satellite finder was temperature sensitive. The LNBF could also be the problem.

Figure 5. Sidereal Time Plots

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The next year (2009), I built a 1.4 GHz system (with helical antenna). I used the FSM as a detector [9]. However, the baseline again drifted in the cooler night temperature. This time, I put the helical system detector with a light bulb in a Styrofoam bucket to temperature stabilize the detector. A night picture of that homemade heat bath is shown in Figure 6. (I remember that the extra light attracted insects at night.) Figure 7 shows a comparison of the dish vs the helical system (same signal source and same antenna elevation angle). Notice the helical data baseline did not drift. While crude (and not recommended), the temporary solution solved the baseline drift problem. (Also notice that graph shows the difference between narrow and wide beam antennas. The antenna beam is mathematically convolving the signal from the Milky Way galactic center.)

Figure 6. Helical system detector homemade heat bath

Figure 7. Baseline Comparison for Dish vs Helical (detector heated)

Returning to the dish system, the Milky Way was detected and the sidereal time difference between two consecutive days was measured to the resolution of the sampling rate (1 sample per minute). A little later I disassembled the system after a few more observations at different points along the Milky Way. A couple of

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months later, it occurred to me while reexamining the data that I could make an angular measurement of the galactic plane without having to set up the radio telescope again. 3.2 Milky Way angle I realized that I had made two Milky Way runs near Orion in the Milky Way at different antenna elevations. I then realized I could use those two runs to calculate the Milky Way angle. (It is important to keep records of one’s observations to avoid losing data because it is very easy to later forget.) Before I begin, antenna elevation is calculated from one’s latitude and the desired declination one is interested in observing [10]. The Milky Way calculation is explained geometrically in Figure 8. Think of side “a” as the declination and side “b” as Right Ascension (RA). The angle theta is the angle of the Milky Way and represents arctangent (Declination/Right Ascension).

Figure 8. Milky Way Triangle

The data curves are shown in Figure 9. The value of triangle side “a” is the difference between the two declinations (28-20), but the Right Ascension time (triangle side “b”) must be converted to the same day. I used 4 minutes for the sidereal time to put both data curves on the same day. (I know the sidereal time is less than 4 minutes, but this was a back of the envelope calculation.) I also used the center of the signal “bump.” With the data now on the same day, I found the difference in time (for that day) to be 12 minutes which converted to 3 degrees (using 0.25 degrees/minutes). Now both the Declination and RA are in degrees. The angle of the Milky Way is found by calculating the arctangent (8/3) which is 69.4 degrees. Thus, we have experimentally measured the angle of the Milky Way near Canis Major (big dog constellation with Right Ascension 7 and Declination -20 degrees and near the Orion constellation).

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Figure 9. Milky Way angle data

For the Milky Way at that particular location, I used the RAs and the declinations with an Orion DeepMap 600 star map to geometrically measure the Milky Way angle. I used the average of the Milky Way contour on that star chart. The reference angle from the star map was 63.4 degrees. The experimentally determined Milky Way angle was less than 10% from the star chart, so I was satisfied. The primary error in the calculation was due to antenna pointing angles (very crude). Minor error sources would be not using the exact sidereal time and possible laptop computer time drift. In summary, I got into radio astronomy with a simple and inexpensive system [11]. With that cheap system, I was able to measure the antenna beamwidth. I upgraded the simple system with a data logger, which enabled me to measure sidereal time and calculate the angle of the Milky Way to within 10%. This system got me into radio astronomy, but I found that moisture in my area often interfered with the 12 GHz signal. The radio telescopes that I built later were at lower frequencies. For beginners to radio astronomy, I recommend the two books [1]. References [1] Radio Astronomy Projects 3rd Edition by William Lonc (292 pages) is a practical book about experiments with a radio astronomy system (www.radiosky.com/booksra.html) and Radio Astronomy Teacher's Notebook 3rd Revised Edition (150 pages) a practical book about building radio telescopes (www.radiosky.com/booksra.html). Both books are now sold as a package for $24 plus shipping. The first book was very good, and the second book was a little dated with many typing errors, but was useful with plans, suggestions, and good ideas. Lonc’s book describes Right Ascension (R.A.) and Declination on pages 4-10. Lonc describes minimum detectable signal on pages 11-15. [2] http://www.setileague.org/askdr/radiomet.htm gives an example of power from the sun for a 500 MHz bandwidth which is p=kTB = (1.38*10^-23 )*5780*500 MHz = 3.98*10^(-11) or about 40 pico watts. This means dBm = 10 log [(3.98(10-11))/1 milliwatt] = -74 dBm of signal. It gets even worst if one considers the angular size of the sun and beamwidth of the dish. A narrow beam dish is seeing a lot of cold space compared to the 0.5 degree diameter of the sun. So more gain is needed (e.g. dish gain and LNBF gain). [3] This particular antenna was a Dish 2000-2 antenna. It was 23"x19" oval dish and could receive three

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satellites via three LNBs and three feedhorns (Dish Pro). This dish and LNBF receives satellite signals in the range of 12.2 to 12.7 GHz (Ku band) and the LNBF down converts and filters the signal to 950 to 2150 GHz (C band). (2150-950 = 1200 GHz bandwidth). I used the center feedhorn and LNBF. Note the center feedhorn is not the center jack on the base of the LNBF. The dish was a 25 ¼” wide by 20 ¼” oval. [4] The SF95LK satellite finder kit had a satellite finder and battery pack. It has an input level of -25 to -75 dBm. The satellite finder had 11 dB gain and bandwidth of 950 - 2050 MHz (1100 MHz). The system (dish and LNBF) received the signal and the satellite finder detected the signal, displaying the signal power on a meter and as an audio tone. (I found the gain for the dish and the LNBF on the internet, but I forgot where I put that data. (Seems like both gains were around 30 to 35 dBs.) The unit connected to the LNBF with type F connectors so I used cheap RG6 satellite coax cables. I later disconnected the audio tone because it was annoying. [5] Using the formula in Radio Astronomy Projects 3rd Edition by William Lonc on page 271, I calculated the sun’s RF power. Power = polarization loss * antenna efficiency * flux * 1*10^(-26) * bandwidth * area of antenna. For 50% polarization loss and 50% antenna efficiency, I calculated the dish’s area using a 20” diameter as 0.2 meter squared (although the oval dish is not a parabola because it feeds three feedhorns). The satellite finder had the narrowest bandwidth (1100 MHz). The flux values for the sun and the Milky Way are given at http://en.wikipedia.org/wiki/Jansky as 10 GHz for the sun 4*10^6 Jy and 2*10^3 Jy for the Milky Way. (For this example 10 GHz is close to 12 GHz.) Using the above values, the power of the sun is 22.2 picowatt and 1.111 *10^(-15) watts for the Milky Way. The watts were converted to dBm by the formula 10*log(watt/milliwatt). The sun was -86.5 dBm and the Milky Way was -111.1 dBm. For a dish gain of about 30 dB, LNBF gain of about 30 dB, and satellite finder input level of -25 to -75 dBm, the RF link budget was 30 + 30 + 75 = 135 dB, so the system had enough gain to receive the weaker Milky Way signal. Therefore, I would not need any inline amplifiers or cheap attenuators. [6] The time measurement is the half power point (half of peak to bottom baseline). This is called the half power beamwidth (HPBW). Time is converted to degrees by multiplying by 0.25 degrees/minute which is 360 degrees / (24 hours * 60 min/hour). The measured time was 9 minutes which is 2.25 degrees. That sounds about right since satellites are pretty close to each other in geostationary orbit. This particular antenna had three feedhorns, which means the oval dish feeds all three feedhorns. (Thus, a simple calculation of the diameter of the dish will not yield the dish beamwidth.) [7] Kenneth Kornstett, “Cheap and Simple Demonstration Radio Interferometer,” SARA Journal 2014_oct.pdf, pp 28-35. [8] http://en.wikipedia.org/wiki/Sidereal_time [9] I do not remember why I did not use the satellite finder as the detector (for the helical antenna radio telescope). I may have accidently damaged it. I went through a couple of cheap satellite finders over the last few years. My last satellite finder was about $7 plus shipping. I later made a detector using Schottky diodes. [10] Declination is calculated from the formula: antenna elevation = 90 – latitude + declination. This formula was found on page 36 in the “Radio Astronomy Teacher's Notebook 3rd Revised Edition” book in reference [1]. [11] The cheap system cost less than $70, but I only bought a satellite finder and power inserter. The satellite dish and LNBF were free. I did not include the price of the two books or the data logger (since I had all the parts on hand).

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Kenneth Kornstett holds a Masters of Physics degree from the University of Tennessee. He has worked in various technical and engineering jobs for various companies in the US and overseas. He once taught several three day microprocessor seminars in major cities across the US in the 70s. He can be contacted at kennethk_us@yahoo.com. Please put “Milky Way” in the subject line. Documentation Dave Typinski As the saying goes, “no job is complete until the paperwork is done.” This was a lesson learned by all (we hope) upon their first trip to the bathroom. For me, the lesson was driven home even more when I became an aircraft mechanic. You can’t touch an airplane without filling out some kind of form – at least the FAA says you’re not supposed to, and for good reason. Screw up an airplane and people die, simple as that. In radio astronomy, nobody is going to die if you mess something up or forget to document what you did. You will, however, feel pretty lousy when you realize all your effort was for naught because you got lazy and didn’t do the documentation and you have to do everything all over again. That’s a lesson we’ve all had to learn the hard way at one time or another. If you design something, build something, change something, or make an observation, then documentation is very important. Documentation of failures is even more important – so you don’t waste time and money trying the same thing again. An engineering log is one of the first things one should begin when starting out in radio astronomy. Two logs, even: one for observations you’ve tried and/or made, and one for the station hardware engineering. Observation logs are common in amateur optical astronomy, but unfortunately not so much in amateur radio

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astronomy. If your radio telescope runs 24x7 on autopilot, then the data itself can be an observation log. Otherwise, it is very useful to keep a log of what you observed and when you observed it, the prevailing conditions (lots of RFI?), the equipment used, and the results. An engineering log is important because it lets you understand how the changes you’ve made to your telescope affect your observing success. Moreover, it allows you to look back and see what your configuration was when someone asks you what you used to get that really cool data three and a half years ago. This log should include things like antenna configuration, feed line loss, and receiver configuration – frequency, pre-detection bandwidth, gain settings, FFT parameters and anything else you can possibly think of. Going to all the trouble of setting up a nice, calibrated radio telescope without keeping an engineering log is a one way ticket to avoidable regret. Then we come to the observing reports themselves. Just like they taught us in high school English class, you should document the five W’s: who, what, when, where, and why. The “how” is covered by the engineering log, but so what: put it in your report anyway since anyone reading your report probably doesn’t have access to your engineering log. The report should be meaningful: your observatory location, who did the observing, what was observed, when it was observed, why you wanted to observe it, a description of the instrumentation used, a description of the data processing, and then of course a description of the results of your effort. If the report is one among a series of ongoing observations, then a thorough write-up is not necessary until you tie them together with a more elaborate description and package it for publication. It is usually enough to log only the particulars of the observed emission, leaving most of the instrumentation description out of it if nothing has changed since the previous such report. If the report is to stand by itself, however, then it should contain all the information necessary to allow someone else versed in the field to duplicate your results. That’s simply how science works. For example, merely stating “we used a receiver tuned to 20 MHz with the AGC turned off” isn’t good enough. What receiver? Make and model? Demodulation mode? Likewise, the data processing description must contain all the pertinent details. “We used FFT analysis” doesn’t mean much if you don’t describe the FFT parameters or the raw data. Same for data decimation and autocorrelation (data folding). Plots used in the report should have meaningful axis labels, with units. A y-axis label of “Amplitude” is almost as bad as no label at all. Amplitude in what? Janskys? Candlepower? Decibels? (Relative to what?) Kilograms? Oompa-Loompas? Well, you get the point. If you’re making a claim of an uncommon observational feat – say, that you observed a radio burst from Zeta Reticuli at 146 MHz – then you should back up your claim with good evidence. Merely pointing at a bump on a plot isn’t good enough here. You have to explain – in detail – why you think that bump represents Zeta Reticuli instead of a random fluctuation in the background noise. Nobody is perfect – we all forget to log something here and there, and we all omit an important piece of information from documentation now and again because it seems “so obvious” at the time. Unfortunately, we nearly always regret it when we realize a few years (or days) later that the undocumented whateveritis is no longer so obvious. In sum, if you take yourself and your radio astronomy efforts seriously, and if you respect yourself as an amateur scientist – or as a professional scientist, for that matter – then thorough documentation is your best friend. Sure it’s a pain, but it’s worth it. I encourage everyone to document as much as they can, whenever they can.

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Dave Typinski is a professional businessman and amateur scientist who has been tinkering with things electrical and mechanical since he was old enough to hold a soldering iron and a Crescent wrench. He is an active member of the Radio Jove project, operating AJ4CO Observatory in High Springs, Florida.

The 21 cm feed SETI pioneer Dr. Frank Drake used in 1960 for Project Ozma, the first modern SETI experiment.

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Scientific Method Steve Olney (VK2XV) – NRARAO The scientific method is discussed and why it is important to adhere to its principles. Wired for Optimism

Studies have shown that we are hard-wired to be optimistic. When a group of individuals are asked to estimate the likelihood of certain events occurring they are prone to over-estimate the likelihood of good things happening (winning the lottery) and under-estimate the bad things (getting cancer). Furthermore, when presented with the actual probability of these events, these same individuals, upon re-questioning, revised their estimates upwards if they were overly pessimistic originally. However, if they were overly optimistic originally they tended to keep their optimistic view. In other words we tend to look at the world through rose-coloured glasses. It also explains why individuals who by nature have a realistic view of life tend to be labelled as pessimists. While there are probably good evolutionary reasons for this optimistic view of the world (otherwise we might never have emerged from the caves for fear of the saber-toothed tiger), it makes us inherently poor estimators of the real world. That is, we naturally use what could be termed the Human Nature Method (HNM) rather than the scientific method. Cherry-Picking

We all have our own particular view of the world and we garner support for that view by referring to 'evidence'. Unfortunately we are very much prone to selecting that evidence which supports our view, whilst rejecting the evidence which does not – cherry-picking. Proponents of particular ideologies select facts and figures which seem to confirm their ideas. Unless the listener has access to ALL the data it is difficult to detect cherry-picking. One can be reasonable suspicious when only a small amount of supporting data is supplied, especially when the topic is complex. The bad news is that cherry-picking can occur on both input data and the presentation of results. The good news is that it can largely be avoided by adhering to the scientific method. An Example

The following example is drawn from real data and outlines the effect of NOT adhering to scientific methodology. Detection of the Vela Pulsar

Currently I am involving in a personal quest to build a system which can detect the signals from the Vela Pulsar. As part of that endeavour I have developed hardware and software customised for the purpose. During testing activities I have collected daily data runs of 4 hours duration for 28 days (when Vela is transiting). This principally was to do an RFI survey at the selected observational frequency of 400 MHz as well as a stress test of the software. The antenna used was an existing 6M (50 MHz) dipole at a height of 3m. The LNA and BPF were located at the receiver indoors and there was a 20m run of RG-58 coaxial cable between the antenna and the first LNA.

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Daily Analysis

While calculations predict that the Vela Pulsar signal should be more than 10 dB below the noise level, examination of daily data showed that on some days there appeared to be a signal right on the predicted frequency of the pulsar.

Figure 1: Example Daily Analysis Out of the 28 daily data runs 9 days show a peak of varying amplitudes right on the predicted Vela Pulsar frequency for that day. Applying the HNM (Human Nature Method) principle it could be surmised that the days which do not show a significant peak at the predicted Velar Pulsar frequency could have been subject to cross-polarisation losses or RFI and so could be eliminated from the analysis. The analysis software has the ability to compensate for the drift in topocentric frequency from day to day ('diurnal tracking') and analysing and summing the 9 daily data files with a peak > 1 standard deviation gives the result shown in Figure 2.

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Figure 2: Incoherent Summing of Daily Data with SD > 1 The sigma level for the peak at the predicted Vela Pulsar frequency is 5.7 which specifies that the probability of this being random is 1 in 26 million. OK – we know we have eliminated 'inconvenient' data, but we are reluctant to dismiss this result. Perhaps we can vindicate this result by making a prediction. As the result in Figure 2 was produced by summing topocentric corrected data, if we sum instead without correction we should see a smaller peak which also should be wider as the 'pulsar peak' drifts lower in frequency as each day passes. This result is shown in Figure 3.

Figure 3: Incoherent Summing Without Diurnal Tracking

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Here we can see that the peak has broadened and dropped in amplitude and also the peak has drifted lower in frequency as predicted. As the days are summed we would expect the peak now to be averaged in frequency by an amount of half the end to end drift. The drift from the first day to the last day is calculated to be ~ -24ppm. The peak in Figure 3 is offset by half that amount at ~ -12ppm. Perhaps by now we are tempted to overlook the elimination of the 'bad data' days. Perhaps we can display the data in a more challenging way to support the result in Figure 2. Let's widen the display to include more frequencies as shown in Figure 4. Still we have a peak at the predicted frequency, but now sigma has dropped to 4.27. This is still a probability of being mere chance of 1 in 150,000. On face value, fairly convincing.

Figure 4: Wider Display Once again we repeat this with diurnal tracking turned off as shown in Figure 5. The peak at the predicted frequency has disappeared into the noise as expected.

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Figure 5: Wider Display Without Diurnal Tracking Comment

So we are left with a result where there appears to be a signal which behaves like a Vela Pulsar signal (tracks exactly as the expected daily drift in topocentric frequency) which holds over a time span of 28 days. The question is: Is this a valid result? The answer is: NO!!! Despite looking like a very convincing detection of the Vela Pulsar signal it is invalid. Why? Because it violates a basic principle of the scientific method which states data cannot be excluded on the basis that it makes the result look bad. Of course we can eliminate data which is obviously corrupted before analysis, but not after doing analysis which identifies data which is 'inconvenient'. The only valid result for this whole exercise is shown in Figure 6 which is the result of incoherently summed ALL 28 days of data. This shows that a peak can be seen in the data at the predicted frequency, but at a level which is statistically insignificant. An 'encouraging' result – but not a valid Vela Pulsar signal detection.

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Figure 6: All 28 Days Summed Without 'Cherry-Picking' Conclusions

There are good reasons for the development of the scientific method. It is the best method for establishing the probability that a result is valid or otherwise. It is not sufficient to simply present data as shown in Figure 2 which looks very convincing. The principle of eliminating data simply because it makes the result look bad violates a basic principle of the scientific method. Another principle is 'peer review'. Results which are protected from peer review must be viewed as invalid. Details of how the data was captured and how, if any, data exclusion was done must be presented. The power of this technique is that the review is being done by other parties who are not emotionally attached to the result. Leave the 'cherry-picking' to the politicians…

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Reber’s Cosmology Dave Typinski March, 2015 The January-February 2015 issue of the SARA journal, Radio Astronomy, included a reprint of a 1989 article by Grote Reber.[1] Most radio astronomers, this author included, place Mr. Reber on something of a pedestal, for he performed the first real radio astronomy—and he was an amateur to boot. His view of cosmology therefore came as a great surprise. Not so much because he was wrong, but because he was writing more like a True Believer than a scientist. His emotional insistence that observed red shifts do not indicate an expanding universe is a good cautionary tale for all scientists, amateur and professional alike. Mr. Reber was, apparently, a staunch opponent of big bang cosmology, liking instead something called the “tired light” hypothesis to explain the red shifts observed in the spectral lines in light from distant galaxies. He did not like the idea that these red shifts were being used as evidence of cosmic expansion in support of the big bang theory. This in itself was okay – he was in good company at the time. Unfortunately, he and his good company turned out to be wrong. One can only wonder what he would have thought about the fact that the universe is not only expanding, but expanding ever faster. The jury is still out on exactly what happened at the instant of the big bang itself, but best anyone can tell, the universe is expanding and the observed red shifts are produced by this expansion. Recent observations falsify tired light theory in three principal ways.[2]

♦ Distant galaxies observed in the Hubble Deep Field are not blurred, thus the Compton scattering mechanism at the heart of tired light theory cannot be at work. Scattered photons do not make clear pictures.

♦ Tired light theory cannot account for the observed time dilation in high red shift supernova decay times. Tired light predicts the same characteristic decay time regardless of red shift. We observe, however, that red shifted supernovae take longer to decay, and the greater the red shift, the longer the decay time.

♦ Tired light theory does not predict the correct spectrum of the cosmic microwave background radiation (CMBR). The CMBR spectrum predicted by tired light theory disagrees with the CMBR spectrum observed by COBE by about 100,000 standard deviations. This puts tired light in Wolfgang Pauli’s “not even wrong” category.

All of which would have been no problem had Mr. Reber been a bit more careful with his emotional attachment to a pet theory. When rational scientists receive data that contradicts their views, they simply change their minds accordingly. This can be somewhat painful, however, if one has already publicly called the opposing camp a bunch of reactionary idiots like Mr. Reber did. Mr. Reber’s fondness for tired light was an opinion to which he was entitled, for he did not have the benefit of the recent observation data that falsifies the theory. There is little excuse, however, for not understanding the core concept against which one is railing. Mr. Reber complained that the observed spectral shifts could not be Doppler phenomena because a) there are no observed blue shifts*, and b) the spectral shifts are proportional to distance. The problem here is that such phenomena are exactly what one would expect if the spectral shifts were due to cosmic expansion. * There are in fact observed blue shifts. For example, the Andromeda galaxy exhibits a blue shift and will likely collide with our galaxy in about 4 billion years or so. Blue shifts are rare because cosmic expansion swamps the

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peculiar motion of the observed galaxy – unless the galaxy is nearby, where the velocity due to cosmic expansion is low. Grote Reber was a great radio astronomer, pioneering a field where others saw nothing useful. He made a huge contribution to the field and is worthy of our respect and admiration for that. As a cosmologist, however, perhaps not so much. There are plenty of things about which we don’t know everything – dark matter, dark energy, mass… even the humble electron. All of these concepts are just names, placeholders for our ignorance about what these things are on a deeper level. Some of them may – probably all of them, eventually – turn out to be a quite different than we imagine. A good scientist leaves room for that. References & Further Reading [1] Reber, G., The Big Bang is Bunk, Radio Astronomy, Jan-Feb 2015; originally published in 21st Century Science & Technology, Mar-Apr 1989. http://www.21stcenturysciencetech.com/Articles_2011/BigBang_Bunk.pdf [2] Wright, N., Errors in Tired Light Cosmology, UCLA, 2008 http://www.astro.ucla.edu/~wright/tiredlit.htm Susskind, L., Cosmology (online lecture videos, 14 hours), Stanford, 2013. https://www.youtube.com/watch?v=P-medYaqVak&list=PLpGHT1n4-mAuVGJ2E1uF9GSwLsx7p1xtm Susskind, L., Modern Physics – The Theoretical Minimum, Stanford, 2009 http://newpackettech.com/Resources/Susskind/Susskind.htm Dave Typinski is a professional businessman and amateur scientist who has

been tinkering with things electrical and mechanical since he was old enough to hold a soldering iron and a Crescent wrench. He is an active member of the Radio Jove project, operating AJ4CO Observatory in High Springs, Florida.

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JJRO Observation Report Julian Jove Julian Jove is a prolific radio observer (PRO) who routinely produces totally astounding results as seen in the time-spanning example below, which was submitted to us next year. JJRO Observation Report Date: 01 April 2016 Observer: Julian Jove Target: Pulsar Q0496+102 Left Descension: 27h32m14.93s Superation: +102.4762932° P0: 19.32478956234879 microfortnights S400: 247.6 horsepower fortnights per square furlong Frequency: 314159265.3589793 cycles Bandwidth: 5.00+j7.35 Tempo5 setting: 12 Facebook score: -10101 x 10-7 Hagen factor: dv/dt = 0 Saturation instability setting: Not applicable

Antenna: AE-35 variant (dual bipolar) Reflector Surface: pre-fabulated amulite, 1/10 zeta Feed Horn: fractal cubic spline VHF hyper-torus (bipolar) Preamp: panametric semi-deltoid, liquid dark matter cooling Receiver: CRM-114 with wide bandwidth option, OPE variant Integration Time: 82.7 nanofortnights Dzus callout: 0.0045 twits/tweet Log Switch: OFF, Branch Switch: ON, Leaf Switch: MEDIUM Detector DC Offset: 0+j6 volts (phase angle only) Johnson bar: Engaged Data Processing: reverse Runge-Kutta anti-discretization Period Analysis: double hermaphroditic non-linear time compression manual auto-erotic-correlation Binary level criterion: 17 nibbles

0

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Time (microfortnights) — 82.672 nanofortnights per tick

Pulsar Q0496+102 Observed April 1, 2016

BINARYPULSAR

OTHERPULSARS

NIBLONIANMOTHER

SHIPRADAR

LINENOISE

PULSAR Q0496+102

BINARYPULSARAGAIN

WASHINGMACHINE

BURP CIA MINDCONTROL

RAYS

EVENMOREOTHER

PULSARS

FOREGROUND NOISE BASELINE

STANDARD DEVIATION REFERENCE

DATA CESSATION

POINT

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Book Review: Radio Propagation ~ Principles and Practice Author: I. Poole Publisher: Radio Society of Great Britain (RSGB) ISBN:978-1872-309972 Date published: 2004 Length: 102 pages, 2 page index Status: In print Availability: Paperbound from ARRL for US$30 or RSGB for £9.99 (about US$17) (see text) Reviewer: Whitham D. Reeve Radio propagation is an important subject for radio astronomers and radio operators, among others. Radio Propagation ~ Principles and Practice was written from the perspective of high frequency terrestrial communications as are almost all amateur radio books on this subject. Someone new to radio astronomy could use this book to learn the fundamentals of radio propagation from the bottom up. They could then move to more advanced books or professionally written online materials that discuss propagation through the ionosphere from the top down. As printed on the back cover, the author is “an electronics and engineering consultant and journalist at Adrio Communications”. He also publishes the Radio Electronics website at http://www.radio-electronics.com/, “Resources and analysis for electronics engineers”, which is a source of numerous highly simplified electronics tutorials. His writing style is British English (not unexpectedly). Radio Propagation ~ Principles and Practice has 10 chapters: Electromagnetic waves; The atmosphere; The Sun; Propagation near the ground; Ionospheric propagation; Ionospheric disturbances, storms and auroras; Predicting, assessing and using ionospheric propagation; Tropospheric propagation; Meteor scatter; and Space communications. The chapters are compact, fairly well-illustrated and easy to read but readers should not expect a lot of depth. Even though the processes that form the ionosphere are very complex, and even today are not completely understood, this book shows that it is possible to skirt the math and provide relatively simple explanations. I spotted only a few simple equations. The book starts out by describing electromagnetic waves, the atmosphere (and ionosphere) and the Sun. These set the stage for discussions of the various types of high frequency propagation discussed later. I noted some discussions that were either too simplified or only partially correct. For example, in chapter 3 – The Sun, the author first states that the Sun rotates faster at its equator and low latitudes than high latitudes and then on the next page says the Sun’s equator rotates slower (the former is correct). The next two chapters cover ground wave and sky wave propagation and include a little history on how the ionosphere was discovered (readers wanting more historical detail should see Probing the Sky with Radio Waves ~ From Wireless Technology to the Development of Atmospheric Science by Chen-Pang Yeang, which I will review in the near future). Chapter 4 – Ionospheric Propagation describes refraction and reflection of radio waves in Earth’s upper atmosphere, which is ionized by the Sun’s radiation. Refraction, or bending, through the ionized medium at altitudes of a few hundred kilometers allows radio waves to travel far beyond the visible horizon. However, the ionosphere is quite variable throughout the day and changes drastically at night, which

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affects the maximum and minimum usable frequencies for any given path. The author’s discussions of the Maximum Usable Frequency (MUF) and Lowest Usable Frequency (LUF) could have been better written. A reader unfamiliar with these terms, in other words, the target audience for this book, might find the discussion confusing. Many radio astronomers are interested in detecting meteor trail reflections, the subject of chapter 9 – Meteor scatter. When a meteor encounters the resistance of Earth’s atmosphere, heat from friction ionizes the thin air and the molecules in the meteor body and leaves an ionized trail that refracts or reflects terrestrial radio waves. The electron density in these trails can exceed the density of the normal ionosphere. The trails usually last only a short time before they dissipate, but they may be used for terrestrial communications (meteor communications), which is the focus of this chapter. I was a little disappointed in the last chapter on Space Communications. While the primary purpose of the book is terrestrial radio propagation, as a radio astronomer I am interested in reception of radio waves from celestial sources through Earth’s ionosphere, the equivalent of receiving from a spacecraft or satellite. I was hoping for more details than provided in this chapter. Faraday rotation and scintillation are very briefly discussed in terms of Earth-Moon-Earth (EME) communications (but too briefly to be of any use). This chapter yielded little else besides what seemed to be a focus on satellite orbits. Of course, in a small book like this, there is little opportunity to provide very many technical details, but I still think it should have been more to the point. I found some passages repetitious, but the discussions are adequate for purposes of amateur radio. The book provides many rules of thumb that could provide a stepping stone for further study. Unfortunately, like almost all books written for the radio amateur market, there are no references or even a list of books for further study. This is a serious impediment to someone wanting to learn more and makes this book easily disposable. This small book may be purchased directly from RSGB. The American Radio Relay League (ARRL) also sells the book but their price is far too high. Interestingly, when I started writing this review (June 2014), used copies were selling for a shocking US$300. The book is not a so-called classic and that price is off by a factor of at least 30. More recently (January 2015) I have seen used prices from 14 to US$35, still too high for a used book of this type. In conclusion, Radio Propagation ~ Principles and Practice provides an adequate introduction but it lacks depth. Although the book has little direct applicability to radio astronomy, it would help a newcomer to amateur radio astronomy to understand some of the characteristics of high frequency propagation and contribute to their overall knowledge. The inconsistencies that I mentioned along with several editing mistakes are minor flaws. However, at US$30 plus shipping, the book is overpriced for US buyers unless they order directly from RSGB at a lower price or are able to find an inexpensive used copy.

Reviewer - Whitham Reeve presently is a contributing editor for the SARA journal, Radio Astronomy. He worked as an engineer and engineering firm owner/operator in the airline and telecommunications industries for more than 40 years and has lived in Anchorage, Alaska his entire life.

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Book Review: The Hobbyist’s Guide to the RTL-SDR: Really Cheap Software Defined Radio Author: Carl Laufer

Publisher: Amazon, Kindle E-Book Price: $9.99 Reviewer: Lee Scheppmann 1. Introduction The Software Defined Radio is becoming an important and widespread tool within the field of amateur radio astronomy. For those new to the field, there is no better and cost effective way to get hands on experience than with a $20 dollar RTL-SDR and this book. For those already using the RTL-SDR, this is the missing manual. This book blew me away. Amazon describes this book as:

A comprehensive guide to the RTL2832U RTL-SDR software defined radio by the authors of the RTL-SDR Blog. The RTL-SDR is a super cheap software defined radio based on DVB-T TV dongles that can be found for under $20.

This book is about tips and tutorials that show you how to get the most out of your RTL-SDR dongle. Some projects described in this book are also compatible with other SDRs like the HackRF.

The RTL-SDR Software Defined Radio is a low-cost, dongle sized, USB device that plugs into a wide range of computer platforms and provides radio frequency reception from about 30 to 1700 MHz. Combined with freely available software, this gives the user almost unprecedented access to the radio spectrum and a wide variety of modulation protocols. For anyone interested in, or currently using an RTL-SDR, this well written, well illustrated, comprehensive, 475 + page, e-book provides an essential reference. This book is closely linked to the RTL-SDR.COM website which hosts information, links, software, drivers, guides, purchasing information, and a forum at http://www.rtl-sdr.com/ . It appears that the e-Book represents a compilation of information from the web-site, and as such, it is a work in progress.

If you haven’t guessed by now, this is almost a complete universe unto itself. These little dongle radios provide such a simple, powerful, and flexible interface between the radio energy around us and the processing power of a computer, that the combination provides almost limitless opportunity for exploration. While the book covers an evolving topic in some 475 pages, I’ll try to summarize it in just a few pages.

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2. Topics Covered The book is not laid out with chapters per se. Since it is an e-book and with the Calibre reader I’m using on the PC, it is a very interactive book. The author has 10 main headings and some 44 sub headings. But for this review I will say that there are four basic sections to the book: 1) Hardware information about the dongle(s), 2) Tutorial on SDR# and other software packages, 3) Descriptions and tutorials of interesting applications, and 4) Supplemental information. The author begins by providing a very good introduction to the RTL-SDR dongle technology: specifications, technical details, and a brief SDR tutorial. There is liberal use of web links that supplement the information that is presented. Basically, if you have a RTL-SDR in front of you with no prior knowledge, Carl will walk you thru getting it up and running. An important part of the book is his description and tutorial of the software, such as SDR# that is used with the dongle. This book serves as a handbook, or “the missing manual” for SDR# and also somewhat for GNU Radio. In my opinion, this section is worth the price of the book alone.

Figure 1. Typical SDR# screenshot The next section goes into detail on a wide variety of applications including ACARS (Aircraft Communications Addressing and Reporting System), Weather Satellite, Weather Balloons/Radiosonde, Digital Audio Broadcasting, Pagers, Trunked Systems, GSM, Tetra, Radio Astronomy, Passive Radar, and D Star. That’s not the complete list. There’s more, lots more. I found that just exploring the list was an adventure and I saw fascinating applications I would not have dreamed of. As a matter of fact there are three chapters which point to the growing body of new work being done with this technology: • Projects For The Future and Better SDR’s • Other Software Not Mentioned Yet

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• Other Interesting Projects People Have Done With The RTL-SDR. These three chapters are filled with links to more information and to active areas of discussion on the RTL-SDR.Com website and blog. For you GNU fans, [ http://en.wikipedia.org/wiki/GNU_Radio ] , there are about 9 pages devoted to the subject. The section on Radio Astronomy focuses on Observing the Hydrogen Line and Galactic Plane. This may not be a simple project, but the author includes some 13 web links to assist the reader and to supplement the information that he presents. The last section consists of three Appendices which cover Audio Piping, Radio Basics, and Multimode Decoding. I’ve left out a lot; however, my guess is that if the subject pertains to the RTL-SDR, it’s probably touched on in this book. One other important point is that much of the material in this book is applicable to other SDR platforms besides the RTL flavors. This is a big plus. 3. e-Readers I want to say a few words about e-Readers. For some time now, I’ve been reading books on a Kindle and that works very well for most books. I have also put the Kindle reader application on my iPad and that also works well. (I’m sure the Android application is similar). But since this book contains a great deal of color material, the iPad application is superior since my Kindle reader only displays black and white. In doing research for this book review, I discovered that there are also great applications which run under Windows. One such application is Calibre at http://calibre-ebook.com/ . It is a free application, and it has the added advantage of enabling the user to create, print, extract, and reformat DRM disabled content. Since this book is DRM disabled, it is a perfect reader for this book. I was able to cut and paste material from the ebook directly into this review. DRM refers to technologies used to control the use of digital content and devices after the sale. 4. Conclusion Like many RTL-SDR users, I have struggled my way thru getting the various applications to work properly with an RTL-SDR and Fun Cube Dongle. I didn’t have this book. But now that I do, it is much easier to explore all of those fascinating projects that this book so clearly covers. This book is a powerful tool for the amateur radio astronomer who wants to explore and utilize Software Defined Radio technology. And, as past and future authors in this Journal have and will demonstrate, the RTL-SDR is an efficient path for getting your project up and running. Lee Scheppmann holds a degree in Applied Physics from San Diego State University and has over 50 years of practical experience in a variety of technical fields. In addition to holding a small number of US patents, Lee has been a founder or co-founder of five startup companies. As KD0IF, Lee has maintained an active interest in radio technology since 1962 and is currently active on the bands up to 24 GHZ. Lee lives with his wife in SE Iowa EN41.

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Membership New Members Please welcome our new or returning SARA members who have joined since the last journal. If your name is missing or misspelled, please send an email to treasurer@radio-astronomy.org. We will make sure it appears correctly in the next Journal issue. As of December 20, 2014: First Name Last Name City State Country Ham ID

Ted Avraham Rockville MD USA

G Dan Chow Oakland CA USA William “Skip” Crilly Dunbarton NH USA Gary Fender Celina TN USA Skyler Freeman Kingston Ontario Canada Alan Fronk Oceanside CA USA KI6WX Linda Goldstien San Francisco CA USA Jack Gross Bedford VA USA KI4DL William Hill Miliani HI USA WH7CQ Brian Kissell Albany Creek QLD Australia Samant Kumar Cupertino CA USA Iris Lee Sunnyvale CA USA Edward Molishever Berkeley CA USA Francis Mondana N Hollywood CA USA Robert Olla Cedar City UT USA Maynard Pittendreigh Orlando FL USA

Gil Raineault Notre-Dame de-Lourdes MB Canada VE4ACQ

Phil Scherrer Castro Valley CA USA Hans Schulze Palo Alto CA USA Leif Svalgaard Petaluma CA USA Jean-Pierre Waymel Ris Orangis France F5FOD Bruce Weber Mississauga Ontario Canada VE3IL Glen Worstell Felton CA USA KG0T William Zimmerman Albuquerque NM USA

SARA Membership Dues and Promotions Membership dues are $20.00 US per year and all dues expire in June. Student memberships are $5.00 US per year. Members joining from June to December of 2014 will renew their membership June 2015. Members joining January to June 2015 will renew June 2016. Or pay once and never worry about missing your dues again with the SARA Life Membership. SARA Life Memberships are now offered for a one-time payment of twenty times the basic annual membership fee (currently $400 US).

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Journal Archives & Other CDs Promotion The entire set of The Journal of The Society of Amateur Radio Astronomers is available on CD. It goes from the beginning of 1981 to the end of 2013 (over 5000 Tor of SARA history!) Or you can choose one of the following CD’s or DVD:* (Prices are US dollars and include postage.)

SARA Journals from 1981 through 2013 SARA Mentor CD, compiled by Jim Brown SARA Navigator (IBT) CD and DVD, compiled by Jon Wallace

Prices, US dollars, including postage Members Each disk $15.00 Disk + 1 year membership extension $30.00 Non-members Each disk $25.00 Disk + 1 year membership $30.00 Non-USA members Each disk $20.00 (airmail) Disk + 1 year members extension $35.00 *Already a member and want any or all of these CD’s or DVD’s? Buy any one for $15.00 or get any three for $35.00. SARA Store (http://www.radio-astronomy.org/e-store) SARA offers the above CDs, DVDs, printed Proceedings and Proceedings on CD and other items at the SARA Store: http://www.radio-astronomy.org/e-store. Proceeds from sales go to support the student grant program. Members receive an additional 10% discount on orders over $50 US. Payments can be made by sending payment by PayPal to treasurer@radio-astornomy.org or by mailing a check or money order to SARA, c/o Melinda Lord, 2189 Redwood Ave, Washington, IA 52353 SARA Online Discussion Group SARA members participate in the online forum at http://groups.google.com/group/sara-list. This is an invaluable resource for any amateur radio astronomer. SARA Conferences SARA organizes multiple conferences each year. Participants give talks, share ideas, attend seminars, and get hands-on experience. For more information, visit http://www.radio-astronomy.org/meetings. Facebook Like SARA on Facebook http://www.facebook.com/pages/Society-of-Amateur-Radio-Astronomers/128085007262843

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Twitter Follow SARA on Twitter #radio astronomy1 What is Radio Astronomy? This link is for a booklet explaining the basics of radio astronomy. http://www.radio-astronomy.org/pdf/sara-beginner-booklet.pdf

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Administrative Officers, directors, and additional SARA contacts The Society of Amateur Radio Astronomers is an all-volunteer organization. The best way to reach people on this page is by email with SARA in the subject line SARA Officers President: Ken Redcap, president@radio-astronomy.org, +1 248-630-6810 Vice President: Tom Hagen, vicepres@radio-astronomy.org, +1 248-650-8951 Secretary: Bruce Randall, secretary@radio-astronomy.org, +1 803-327-3325 Treasurer: Melinda Lord, treasurer@radio-astronomy.org, +1 319-591-1130 Past President: William Lord, tbd@radio-astronomy.org, +1 319-591-1131 Founder Emeritus & Director: Jeffrey M. Lichtman, Jeff@radioastronomysupplies.com, +1 954-554-3739 Board of Directors Name Term expires Email Jim Brown 2015 starmanjb@comcast.net Chip Sufitchi 2015 ciprian@sufitchi.com Carl Lyster 2016 ctlyster@bellsouth.net Stephen Tzikas 2016 Tzikas@alum.rpi.edu David James 2016 dave@greenover.net Curt Kinghorn 2015 curtkinghorn@gmail.com Keith Payea 2016 kbpayea@bryantlabs.net Stan Nelson 2015 stannelson@cableone.net Other SARA Contacts All Officers ---- officers@radio-astronomy.org Annual Meeting Coordinator Vice President vicepres@radio-astronomy.org All Radio Astronomy Editors --- editor@radio-astronomy.org Radio Astronomy Editor Kathryn Hagen kathryn.hagen@gmail.com Radio Astronomy Contributing Editor Christian Monstein monstein@astro.phys.ethz.ch Radio Astronomy Contributing Editor Whitham D. Reeve whitreeve@gmail.com Radio Astronomy Contributing Editor Stan Nelson stannelson@cableone.net Educational Outreach Jon Wallace education@radio-astronomy.org Grant Committee ---- grants@radio-astronomy.org International Ambassador Librarian Membership Chair Tom Crowley membership@radio-astronomy.org Mentor Program Jon Wallace mentor@radio-astronomy.org Navigators Tom Crowley tomcrowley@mindspring.com Technical Queries David Westman technical@radio-astronomy.org Webmaster Ciprian (Chip) Sufitchi webmaster@radio-astronomy.org

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Resources Great Projects to Get Started in Radio Astronomy Radio Observing Program The Astronomical League (AL) is starting a radio astronomy observing program. If you observe one category, you get a Bronze certificate. Silver pin is two categories with one being personally built. Gold pin level is at least four categories. (Silver and Gold level require AL membership which many clubs have membership. For the bronze level, you need not be a member of AL.) Categories include 1) SID 2) Sun (aka IBT) 3) Jupiter (aka Radio Jove) 4) Meteor back-scatter 5) Galactic radio sources This program is a collaboration between NRAO and AL. William F Bogardus is the Lead Coordinator and a SARA member. For more information: http://www.astroleague.org/programs/radio-astronomy-observing-program

The Radio Jove Project monitors the storms of Jupiter, solar activity and the galactic background. The radio telescope can be purchased as a kit or you can order it assembled. They have a terrific user group you can join. http://radiojove.gsfc.nasa.gov/

The INSPIRE program uses build-it-yourself radio telescope kits to measure and record VLF emissions such as

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tweeks, whistlers, sferics, and chorus along with man-made emissions. This is a very portable unit that can be easily transported to remote sites for observations. http://theinspireproject.org/default.asp?contentID=27 Sky Scan Awareness Project When a meteor passes through the Earth's atmosphere, it ionizes the atmosphere which improves its ability to reflect radio waves. This allows you to briefly hear a far away radio station that you normally couldn't detect. In this project, you can install an antenna, use an FM radio receiver, computer software, and learn to observe meteor showers using this very simple radio telescope. For more information about this project, please visit http://www.skyscan.ca/getting_started.htm .

SARA/Stanford SuperSID

Stanford Solar Center and the Society of Amateur Radio Astronomers have teamed up to produce and distribute the SuperSID (Sudden Ionospheric Disturbance) monitor. The monitor utilizes a simple pre-amp to magnify the VLF radio signals which are then fed into a high definition sound card. This design allows the user to monitor and record multiple frequencies simultaneously. The unit uses a compact 1 meter loop antenna that can be used indoors or outside. This is an ideal project for the radio astronomer that has limited space. To request a unit, send

an e-mail to supersid_at_radio-astronomy_dot_org

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Education Links From its vantage point 150 million km away from Earth, the ACE (Advanced Composition Explorer) spacecraft provides 15 to 60 minutes warning of deleterious space weather. One problem though, it is getting old. What to do? Replace it with the DSCOVR, the Deep Space Climate Observatory. Read about it here: http://www.nesdis.noaa.gov/DSCOVR/ Grounding vs Bonding, 12 part article series from Electrical Construction & Maintenance (EC&M) magazine: http://ecmweb.com/bonding-amp-grounding/grounding-vs-bonding-part-1-12 Fundamentals of Lightning Protection from the National Lightning Safety Institute (NLSI): http://www.lightningsafety.com/nlsi_lhm/lpts.html EOS, Earth & Space Science News, What Causes Broadband Electrostatic Noise in Space?: https://eos.org/research-spotlights/what-causes-broadband-electrostatic-noise-in-space Texas Instruments eBook, Analog Engineers Pocket Reference: http://www.ti.com/ww/en/analog/ebook/analogrefguide/index.html?DCMP=pocketref&HQS=hpa-pa-opamp-pocketref-em-ebook-en&sp_rid_pod4=MTE1NzMxNTE2MTczS0&sp_mid_pod4=48141666&spMailingID=48141666&spUserID=MTE1NzMxNTE2MTczS0&spJobID=640339707&spReportId=NjQwMzM5NzA3S0 Scientific Computing magazine, Satellite Mission Puts Einstein to the Test: http://www.scientificcomputing.com/news/2015/03/satellite-mission-puts-einstein-test?et_cid=4449533&et_rid=210447177&location=top Monitor space weather, HF propagation, aurora and other related stuff. Download POSEIDON: http://markslab.tk/project-poseidon/ Free eBooks by Jet Propulsion Laboratories on many subjects including the Deep Space Network and space navigation: http://descanso.jpl.nasa.gov/monograph/mono.html NASA Deep Space Network including links to Deep Space Network Now: http://deepspace.jpl.nasa.gov/ NASA Technical Reports Server (NTRS): http://ntrs.nasa.gov/ Want to learn about radio propagation at all frequencies based on work in 1961? If so, go to Journal of Research of National Bureau of Standards, Section D: Radio Propagation: http://www.nist.gov/nvl/journal-of-research-volume-65d.cfm#issue3 Free astronomy text and course: http://www.teachastronomy.com/ Brush up on modern measurement fundamentals with free DVD from Keysight Technologies: https://www.keysight.com/main/editorial.jspx?cc=US&lc=eng&ckey=2566376&id=2566376&cmpid=MA46697AM&MKCID=147535.000000000000000000000000000000 Orban Microwave Products ~

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The Basics of Quadrifilar Helix Antennas: http://orbanmicrowave.com/thebasicsofquadrifilarantennas/ The Basics of Antenna Arrays: http://orbanmicrowave.com/the-basics-of-antenna-arrays/ Texas Instruments, TI Precision Labs is the electronics industry’s first comprehensive online classroom for analog engineers. This free modular curriculum includes over 30 hands-on trainings and lab videos, covering analog amplifier design considerations with online course work: http://www.ti.com/lsds/ti/amplifiers-linear/precision-amplifier-precision-labs.page Anritsu ~ Interference Hunting Tools: https://www.youtube.com/watch?v=Of0rFegWex4 Making Interference Hunting Easier: https://www.youtube.com/watch?v=zm5ymfKGZs4 Maxim ~ A Method of Demonstrating Transmission-Line Behavior on a Dual-Channel Oscilloscope: http://www.maximintegrated.com/en/app-notes/index.mvp/id/5617?utm_source=EE-Mail&utm_medium=newsletter&utm_content=eemail&utm_campaign=eemail Earth & Space Science News ~ Changing of the Guard: Satellite Will Warn Earth of Solar Storms: https://eos.org/project-updates/changing-of-the-guard-satellite-will-warn-earth-of-solar-storms Microwaves & RF magazine ~ Selecting Microwave Amps for Measurements: http://mwrf.com/test-measurement-analyzers/selecting-microwave-amps-measurements?code=UM_UM5DE Physics Today ~ Particle physics and the cosmic microwave background: http://scitation.aip.org/content/aip/magazine/physicstoday/article/68/3/10.1063/PT.3.2718?utm_source=Physics+Today&utm_medium=email&utm_campaign=5494615_Physics+Today%3a+The+week+in+Physics+23-27+March&dm_i=1Y69,39RO7,HPI212,BPI6F,1

Online Resources British Astronomical Association – Radio Astronomy Group http://www.britastro.org/baa/

Radio Astronomy Supplies http://www.radioastronomysupplies.com

CALLISTO Receiver & e-CALLISTO http://www.reeve.com/Solar/e-CALLISTO/e-callisto.htm CALLISTO data archive: www.e-callisto.org

Radio Sky Publishing http://radiosky.com

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Deep Space Exploration Society http://dses.org/index.shtml

RF Associates Richard Flagg, rf@hawaii.rr.com 1721-I Young Street, Honolulu, HI 96826

European Radio Astronomy Club http://www.eracnet.org

RFSpace, Inc http://www.rfspace.com

GNU Radio http://www.gnu.org/licenses/gpl.html

Shirleys Bay Radio Astronomy Consortium marcus@propulsionpolymers.com

Inspire Project http://theinspireproject.org

Simple Aurora Monitor Magnetometer http://www.reeve.com/SAMDescription.htm

NASA Radio JOVE Project http://radiojove.gsfc.nasa.gov Archive: http://radiojove.org/archive.html

SETI League http://www.setileague.org SkyScan Science Awareness (Meteor Detection) http://www.skyscan.ca/getting_started.htm

National Radio Astronomy Observatory http://www.nrao.edu

Stanford Solar Center http://solar-center.stanford.edu/SID/

NRAO Essential Radio Astronomy Course http://www.cv.nrao.edu/course/astr534/ERA.shtml

UK Radio Astronomy Association http://www.ukraa.com/www/

Pisgah Astronomical Research Institute http://www.pari.edu

SARA Facebook page https://www.facebook.com/pages/Society-of-Amateur-Radio-Astronomers/128085007262843

SARA Web Site http://radio-astronomy.org

SARA Twitter feed https://twitter.com/RadioAstronomy1

SARA Email Forum and Discussion Group http://groups.google.com/group/sara-list

For Sale, Trade, and Wanted SARA Polo Shirts SARA has polo shirts with the new SARA logo embroidered. (No pocket) These are 50% cotton and 50% polyester, machine washable. Currently in stock:

Price is $15 with free shipping in the USA. Additional cost for shipping outside the USA. Other colors and sizes available, contact

SARA Treasurer, Melinda Lord, at treasurer@radio-astronomy.org.

Size Color Small Navy, Royal Blue Medium Navy, Dark Green, Royal Blue Large Maroon, Black, Navy, Royal Blue X-Large Maroon, Black, Navy, Royal Blue XX-Large Maroon, Black, Navy, Dark Green, Royal Blue XXX-Large Black, Navy, Dark Green, Royal Blue

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There is no charge to place an ad in Radio Astronomy; but, you must be a current SARA member. Ads must be pertinent to radio astronomy and are subject to the editor’s approval and alteration for brevity. Please send your “For Sale,” “Trade,” or “Wanted” ads to editor@radio-astronomy.org. Please include email and/or telephone contact information. Please keep your ad text to a reasonable length. Ads run for one bimonthly issue unless you request otherwise. For sale

Items listed below. Send request to SARA by email to supersid@radio-astronomy.org. For more information: http://www.radio-astronomy.org/pdf/sid-brochure.pdf .

Description, items for sale by SARA Price (US$) SuperSID VLF receiver (assembled) $48.00 PCI soundcard, 96 kHz sample rate $40.00 Antenna wire 24 AWG (120 m) $23.00 Coaxial cable, Belden RG58U (9 m) $14.00 Shipping (United States) $10.00 Shipping (Canada, Mexico) $25.00 Shipping (all other) $40.00

Description, items for sale by SARA Price (US$) New-in-box twist-on male TNC Connector for RG-58 cable, 23 available $1.00/each New Berk-Tek twist-on male TNC Connector for RG-59 cable, 10 available $1.00/each New twist-on male BNC connector 1-Piece 50 ohm for RG-6 cable, 21 available $1.00/each Belden RG58U Coax 25 CENTS per foot, odd lengths from 13’ to 19’

All are plus shipping. Will consider offers. Items are surplus and all proceeds go to support the SARA/Stanford SuperSID project. Contact Bill Lord (319)591-1131 or email supersid@radio-astronomy.org

For sale by Jeffrey Lichtman: Tektronix C-30A Oscilloscope Camera. Uses polaroid film. $35.00 plus $15 shipping for USA. Foreign shipping, email jeff@radioastronomysupplies.com