This GPS tutorial covers GPS system basics,applications and also provide link to GPS module/chip/components manufacturers.It covers difference between GPS vs AGPS and GPS vs GLONASS.
GPS vs AGPS  GPS Frame Structure  GPS vs GPRS  GPS Basics Tutorial  GPS Antenna  GPS Receiver Module  GPS Satellite  GPS Tracking System 

Both GPS and GLONASS are satellite based navigation systems. GPS was introduced in 1978 by United States and GLONASS in 1982 by Soviet Union. Over the year's research have been pioneered to have devices with both the GPS and GLONASS features. Range measurements in both the systems rely on microwave signals transmitted by satellite.

The table below provides difference between GPS and GLONASS satellite navigation systems with respect to satellite orbits and carrier signals.

Each satellite in both the GPS and GLONASS systems transmits at a rate of 50 bits per second and communicate positioning information to mobile devices on the earth. Due to this slow speed it takes more time to obtain the information, to avoid this problem A-GPS and A-GLONASS systems have been designed.

Both A-GPS and A-GLONASS obtain assitance data at higher speed of about 100 Mbps from the wireless communication network(e.g. LTE base station,GSM/CDMA base station). This makes mobile devices obtain positioning information faster.

Specifications GPS GLONASS
Orbital planes 6 and spaced by 60 degree 3 and spaced by 120 degree
Satellites per orbital plane 4 and unevenly spaced 8 and evenly spaced
Orbital plane inclination 55 degree 64.8 degree
Orbital radius 26560 Km 25510 km
Orbital period About 11 hours and 58 minutes (1/2 of sidereal day) 11 hours and16 minutes
Repeat ground track every sidereal day every 8 sidereal days
carrier signals L1 band: 1575.42 MHz ,L2 band: 1227.60 L1 band:(1602+ k x 9/16) MHz
L2 band: (1246 + k x 7/16) MHz ,
where k is the channel number
codes different for each satellite, C/A code on L1 and P-code on L1/L2 same for all the satellites , C/A code on L1 and P-code on L1/L2
code frequency C/A code - 1.023MHz and P-code 10.23 MHz C/A code - 0.511 MHz and P-code 5.11 MHz(half than GPS)
Clock data In GPS Clock data are transmitted in terms of Clock offset, frequency offset, frequency rate and allow the calculation of the difference between individual GPS satellite's time GPS system time. Broadcasted Clock and frequency offset provides difference between time of GLONASS satellite and GLONASS system
orbital data Modified keplerian orbital elements every hour satellite position, velocity and acceleration every half hour


GPS receiver chip manufacturers  

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