SISTEM KOMUNIKASI SATELIT

BAB I PENDAHULUAN

Topik: 1. Overview Arsitektur komunikasi Satelit 2. Implementasi komunikasi satelit dalam kehidupan sehari-hari 3. Pengaruh komunikasi satelit terhadap sendi-sendi kehidupan modern 4. Overview sejarah komunikasi satelit 5. Overview Regulasi ITU-R

Obyektif Perkuliahan • Mengenalkan kembali dan memahami blok diagram sistem

komunikasi dan mekanisme kerjanya • Mengenal dan memahami sejarah perkembangan komunikasi

satelit, evolusi, dan implementasi serta regulasi dan pengaruhnya.

Referensi : 1. Bruce R. Elbert, “Satellite Communications Handbook”, 2nd

Ed., Artech House, 2004 2. Dennis Roddy, “Satellite Communications”, 3rd Ed., Mc

Graw Hill, 2001. 3. G. Maral & M. Bousquet, “ Satellite Communications

Systems, Technology, and Application,” 3 rd Ed., John Wiley & Son, 2002.

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Arsitektur Komunikasi Satelit

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Segmen Angkasa

TT&C

Uplink Downlink

SB TX SB RX Master Station

Arsitektur Komunikasi Satelit

• Segmen Angkasa: – Struktur / Bus – Payload – Power Supply – Kontrol temperatur – Kontrol attitude dan orbit – Sistem propulsi – Telemetry, Tracking, & Command (TT&C)

• Segmen Bumi: – User Terminal, SB Master, dan Jaringan.

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Jenis Spaceraft

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Spinning Stabilized Satellite, misalnya

Palapa A, Measat, etc

3-axis Stabilized Satellite, misalnya

Telkom-1, Thuraya (UEA), etc

Komponen Dasar Link Satelit

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SB Transmit

SB Receive

Tipe Orbit

• Equatorial, polar, dan inclined orbit.

• GEO (35,378 km), MEO (5000 km – 12.000 km), dan LEO (300km – 2000km).

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Tinggi Orbit dan delay

• Delay merupakan parameter penting yang menentukan kinerja link komunikasi.

• Periode orbit akan menentukan jenis komunikasi satelit, dan juga konstelasi terkait dengan desain cakupan komunikasi.

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Konstelasi Satelit

• Untuk cakupan Global biasanya dibutuhkan banyak satelit yang ditempatkan dalam beberapa bidang orbit, dan spasi antar satelit ditentukan.

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Bentuk Cakupan Satelit

• Global beam, spot beam, dan shaped beam

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Frequency Bands

Band Frequency

Range

Total Bandwidth General Application

L 1 to 2 GHz 1 GHz Mobile satellite service (MSS)

S 2 to 4 GHz 2 GHz MSS, NASA, deep space research

C 4 to 8 GHz 4 GHz Fixed satellite service (FSS)

X 8 to 12.5 GHz 4.5 GHz FSS military, terrestrial earth

exploration, meteorological

satellites

Ku 12.5 to 18 GHz 5.5 GHz FSS, broadcast satellite service

(BSS)

K 18 to 26.5 GHz 8.5 GHz BSS, FSS

Ka 26.5 to 40 GHz 13.5 GHz FSS

General Applications

• Mobile Satellite Service (MSS): Is a satellite system which uses portable terrestrial terminals. MSS terminals may be mounted on a ship, an airplane, an automobile or may even be carried by an individual. The most promising application of Mobile Satellite Service is portable satellite telephones which will enable phone service anywhere on the globe. Another application is global positioning systems (GPS)

• Fixed Satellite Services (FSS): Broadcast feed used between TV networks. Main application is on National Cable Channels supplied to the TV head station

• Broadcast Satellite Service(BSS): This is also known as Direct Broadcast Satellite. communications satellite that transmits to small DBS satellite dishes (usually 18" to 24" in diameter). DBS technology is used for DTH-oriented (Direct-To-Home) satellite tv services, such as DirecTV, Dish Network, and Sky Angel in the United States, ExpressVu in Canada, and Sky Digital in the UK.

Regulasi dan Koordinasi Frekuensi

• Regulasi slot orbit , terutama GEO, dan frekuensi secara internasional dilakukan oleh ITU-R.

• Karena tiap negara berhak mengklaim wilayah udara (space) diatasnya, maka harus dilakukan koordinasi untuk filing orbit dan alokasi frekuensi supaya tidak terjadi overlaping dan interferensi.

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Objektif Regulasi ITU-R

• To facilitate equitable access to and rational use of the natural resource of the radio-frequency spectrum and the geostationary-satellite orbit;

• To ensure the availability and protection from harmful interference of the frequencies provided for distress and safety purposes;

• To assist in the prevention or resolution of cases of harmful interference between the radio services of different administrations;

• To facilitate the efficient and effective operation of all radiocommunication services;

• To provide and, where necessary, regulate new applications of radiocommunication technology.

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Pembagian Alokasi Spektrum ITU

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Definisi Layanan dan Alokasi Frekuensi

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Definisi Layanan dan Alokasi Frekuensi

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Satelit di Orbit GEO (mid-1990)

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Aplikasi Komunikasi Satelit

Sambungan Telepon Internasional

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Telepon dan Data

• Dial-up voice, fax, dan data di multiplex dan diolah (dikompresi) sebelum diinputkan ke modem satelit.

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Direct Broadcasting Services (DBS)

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Fungsi Satelit pada TV Broadcasting

• Distribusi Point-to-multipoint programTV dari studio ke stasiun broadcast lokal;

• Transmisi Point-to-point liputan/siaran langsung ke studio (alternatively, from one studio to another studio);

• Distribusi Point-to-multipoint program cable TV dari studio ke cable TV lokal

• Distribusi Point-to-multipoint program cable TV dan/atau jaringan TV langsung dari studio ke customer (i.e., DTH-direct to home).

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Keberhasilan DTH-DBS Dipengaruhi Oleh Faktor-Faktor:

• Ukuran Antena RX: makin kecil ukuran antena, makin mudah di instal dan murah. Dewasa ini ukuran antena TVRO berkisar antara 35 cm – 80 cm, dan harga sekitar $100 (Rp 1 jt) termasuk set top box.

• Peralatan simple dan mudah dioperasikan.

• Satu antena RX bisa di gunakan bersama-sama (sharing) untuk beberapa user/TV.

• Jumlah transponder yang bisa dibawa oleh Satelit meningkat (umumnya sekitar 32 Transponder)

• Jumlah kanal per transponder umumnya 2 kanal TV analog dan 10 kanal TV Digital. Dengan teknik kompresi yang makin baik, jumlah kanal TV digital bisa ditingkatkan

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VSAT Network

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Perangkat VSAT

• VSAT untuk broadband communications.

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Direct Audio Broadcasting (DAB)

WorldSpace Receiver

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Basic arsitektur DAB

Intersatelit Link (ISL)

• Ilustrasi laser intersatellite link oleh satellite Artemis.

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Keunggulan Komunikasi Satelit

• Cakupan yang luas: satu negara, region, ataupun satu benua

• Bandwith yang tersedia cukup lebar; • Independen dari infrastruktur terrestrial; • instalasi jaringan segmen bumi yang cepat; • Biaya relatif rendah per site; • Karakteristik layanan yang seragam; • Layanan total hanya dari satu provider; • Layanan mobile/wireless yang independen

terhadap lokasi.

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Kelemahan Komunikasi Satelit

• Up Front Cost tinggi: Contoh untuk Satelit GEO: Spacecraft, Ground Segment & Launch = US $ 200 jt, Asuransi : $ 50 jt.

• Distance insensitive: Biaya komunikasi untuk jarak pendek maupun jauh relatif sama.

• Hanya ekonomis jika jumlah User besar dan kapasitas digunakan secara intensif.

• Delay propagasi besar.

• Rentan terhadap pengaruh armosfir, dll

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Overview Sejarah Komunikasi Satelit

• 1957: Sputnik diluncurkan (USSR)

• 1964: INTELSAT (International Telecom-munications Satellite dibentuk beranggota-kan 140 negara.

• 1975: Anik untuk Komunikasi domestik Canada

• 1976: SKSD Palapa (Palapa-A).

• 1999: Telkom-1 diluncurkan.

• 2005: Telkom-2

• 2012: Telkom-3 Gagal mencapai orbit

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Beginnings of satellite communication

• Origins: Arthur Clarke’s article in Wireless World in 1945

• WW-II stimulated development of two key technologies – Microwave communication

– Missile technology

• First satellite launched in 1957 by USSR – Sputnik, 83.6kg, LEO, atmospheric studies

– Mission duration 3 months

• First commercial communication satellite 1967 – Intelsat I - EarlyBird, 34.5kg, GEO, communication satellite

– Coverage between US and Europe

– Operated 4 years (deactivated in 1969)

– Launched from KSC

– Could handle 240 voice and 1 TV channel

– Owned by Intelsat (52 countries)

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Sputnik 1

Intelsat- EarlyBird

Development of satellite communication

• Imagination (1945-1960) – Early days of extensive scientific research

– “Dreaming” of what is possible

• Innovation (1960-1970) – Establishment of governmental space exploration agencies

and international satellite consortia

– Development of communication and rocket technology

– First launches

• Commercialization (1970-1980) – Satellite communication becomes commercial technology

– Applications: cross continental telephony and satellite TV

• Liberalization (1980-1990) – Transformation of international governmental consortia

– Market led approach allowed private investments

– Regulatory framework changes that allowed all of the transformations to take place

• Privatization and private ventures (1990 – on) – Communication satellites become mainstream technology led by

private business

– Leading applications: broadcast TV, data backhaul, mobile communications in the air and on the sea, navigation, etc.

– Future – integration of satellite technology with Internet

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Satellite applications

(values in B$)

History channel documentary: Satellites – how they work

https://www.youtube.com/watch?v=eYUxkSFCKZQ

Soal-soal 1. Sebutkan jenis konstelasi satelit 2. Apa hubungan antara delay dengan ketinggian satelit? 3. Apa yang dimaksudt distance insentive? 4. Sebutkan type orbit

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