autocorrelation yang tajam untuk memungkinkan sinkronisasi kode.semakin rendah harga cross correlation maka jumlah kanal dalam satu pita frekuensi semakin tinggi.

Coarse/Acquisition Code yaitu kode akuisisi kasar merupakan standar sinyal satelit GPS yang ditransmisikan oleh satelit GPS untuk pengguna sipil. Berisi informasi yang berguna bagi receiver GPS untuk memperbaiki posisi dan waktu. C/A Code mempunyai akurasi 100 meter atau lebih baik lagi.

P-Code : jenis kode yang tepat dan sangat akurat dari sinyal GPS biasanya hanya digunakan oleh militer AS. Biasanya terenkripsi dan direset setiap tujuh hari sekali untuk mencegah penggunaan dari orang yang tidak berkepentingan secara sah.GPS Satellite Signals The SVs transmit two microwave carrier signals. The L1 frequency (1575.42 MHz) carries the navigation message and the SPS code signals. The L2 frequency (1227.60 MHz) is used to measure the ionospheric delay by PPS equipped receivers. Three binary codes shift the L1 and/or L2 carrier phase. The C/A Code (Coarse Acquisition) modulates the L1 carrier phase. The C/A code is a repeating 1 MHz Pseudo Random Noise (PRN) Code. This noise-like code modulates the L1 carrier signal, "spreading" the spectrum over a 1 MHz bandwidth. The C/A code repeats every 1023 bits (one millisecond). There is a different C/A code PRN for each SV. GPS satellites are often identified by their PRN number, the unique identifier for each pseudo-random-noise code. The C/A code that modulates the L1 carrier is the basis for the civil SPS. The P-Code (Precise) modulates both the L1 and L2 carrier phases. The P-Code is a very long (seven days) 10 MHz PRN code. In the Anti-Spoofing (AS) mode of operation, the P-Code is encrypted into the Y-Code. The encrypted Y-Code requires a classified AS Module for each receiver channel and is for use only by authorized users with cryptographic keys. The P (Y)-Code is the basis for the PPS. The Navigation Message also modulates the L1-C/A code signal. The Navigation Message is a 50 Hz signal consisting of data bits that describe the GPS satellite orbits, clock corrections, and other system parameters.

Nilai DOP didapatkan dari perhitungan matematis, yang menunjukkan tingkat kepercayaan perhitungan sebuah lokasi. Ketika satelit-satelit terletak berdekatan, maka nilai DOP akan meningkat, yang menyebabkan akurasi alat navigasi berbasis satelit menjadi berkurang. Ketika satelit-satelit terletak berjauhan, maka nilai DOP akan berkurang sehingga alat navigasi menjadi lebih akurat.

Bila nilai DOP lebih kecil dari 5 (ada yang mengatakan dibawah 4), maka akurasi yang akan didapatkan cukup akurat. Ada beberapa nilai akan sering dijumpai, yaitu HDOP (Horizontal Dilution of Precision), VDOP (Vertical Dilution of Precision), dan PDOP (Positional Dilution of Precision posisi tiga dimensi).They dont work indoors, and they only really operate in two dimensions. GPS and GLONASScanmeasure altitude, but generally the data is inaccurate and too low-resolution (on the order of 10-25 meters) for everyday usemultipath propagation where signals skip off structures,weakenedby barometrical conditions, dividers, or tree spread.To be more precise, "A-GPS" features are mostly dependent on an internet network and/or connection to anISP(or CNP, in the case of CP/mobile-phone device linked to a Cellular Network Provider data service). A mobile (CellPhone/SmartPhone) device featured with "A-GPS" (no additional "S-GPS"/Standalone-GPS feature to be selected as alternative, or there is no "Hybrid GPS" as a complete A-GPS/S-GPS hybrid features in one device) can work only when there is an internet link/connection to an ISP/CNP - it is useless in areas with no coverage of internet link (or no BTS towers nearby, in the case on CNP service coverage area) to connect to those A-GPS servers (that are usually provided by CNPs). On the contrary, a "S-GPS" (including "Dedicated GPS") device/feature requires no connection to internet/network to obtain GPS data since it connects directly to GPS satellites swarming overhead in Low Earth Orbit (LEO).Assistance falls into two categories:1. Mobile Station Based (MSB): Information used to acquire satellites more quickly. It can supplyorbital dataor almanac for the GPS satellites to the GPS receiver, enabling the GPS receiver to lock to the satellites more rapidly in some cases. The network can provide precise time.2. Mobile Station Assisted (MSA): Calculation of position by the server using information from the GPS receiver. The device captures a snapshot of the GPS signal, with approximate time, for the server to later process into a position. The assistance server has a good satellite signal, and plentiful computation power, so it can compare fragmentary signals relayed to it. Accurate, surveyed coordinates for thecell sitetowers allow better knowledge of localionosphericconditions and other conditions affecting the GPS signal than the GPS receiver alone, enabling more precise calculation of position.

A-GPS has two modes of operation:Mobile Station Assisted (MSA)In MSA mode A-GPS operation, the A-GPS capable device receives acquisition assistance, reference time and other optional assistance data from a mobile service provider. The mobile service provider continuously logs GPS information (mainly thealmanac) from the GPS satellites using a A-GPS server in its system. With the help of the above data (the data received from the mobile device and the data already present in A-GPS server) the A-GPS server calculates the position and sends it back to the A-GPS device.Mobile Station Based (MSB)In MSB mode A-GPS operation, the A-GPS device receives ephemeris, reference location, reference time and other optional assistance data from the A-GPS server. With the help of the above data, the A-GPS device receives signals from the visible satellites and calculates the position.[5]

Anindoor positioning system (IPS)is a solution to locate objects or people inside a building using radio waves, magnetic fields, acoustic signals, or other sensory information collected by mobile devices.[1]There is currently no de facto standard for an IPS systems design. Nevertheless, there are several commercial systems on the market.

NAVSTAR-GPS, dikendalikan oleh U.S. DoD GLONASS, sistem yang dimiliki oleh Rusia Galileo, milik Uni Eropa (online pada tahun 2019??) Compass/BeiDou-2, sistem navigasi global yang dibangun China , (operational with 10 satellites as of Pendahuluandibangun China , (operational with 10 satellites as of December, 2011; 35 planned) GPS and GLONASS are free to useDGPS1. Penentuan nilai koreksi pada reference stationReference station menerima isyarat satelit dalam jangkauannya dan mengukur jarak satelit tersebut. Jarakdibandingkan dengan jarak yang dihitung dari posisi eksak station, sehingga diperoleh data koreksi galat2. pengiriman nilai koreksi dari reference station ke pengguna GPSNilai koreksi disiarkan pada pengguna GPS melalui beberapa media yang sesuai dan mencakup suatu wilayah tertentu di sekitar reference station.3. Kompensasi pseudorange dengan nilai koreksi untukpenghitungan posisi Setelah menerima nilai koreksi, suatu pengguna GPS akan menggunakannya untuk mengoreksi hasil pengukuran yang dilakukan. Hampir semua galat yang disebabkan karena derau penerima dan multipath dapat diantisipasiWide Area DGPS (WADGPS) disebut juga Satellite Based Augmentation System (SBAS). Pada sistem ini data koreksi galat dikirim melalui satelit dan data yang dikirimkan mencakup semua reference station yang ada dalam sistem jaringanLocal DGPS atau biasa disebut Local Area Augmentation System (LAAS) atau Ground Based Augmentation System (GBAS)Time to First Fix (TTFF) yaitu waktu dari start up hingga dapat melakukan pengukuran posisi