What is GLONASS?
- GLONASS is the acronym for the Global Navigation Satellite System operated for the Russian government by the Russian Aerospace Defense Forces.
- GLONASS provides the only alternative to the United States Global Positioning System offering global coverage and comparable precision.
GLONASS Operation
- GLONASS is a global satellite navigation system, providing real time position and velocity determination for military and civilian users.
- Satellites are located in middle circular orbit at 19,100 km altitude with a 64.8 degree inclination and a period of 11 hours and 15 minutes.
- GLONASS' orbit makes it especially suited for usage in high latitudes (north or south), where getting a GPS signal can be problematic.
- GLONASS satellites transmit two types of signals; A standard precision (SP) signal and an obfuscated high precision (HP) signal.
- At peak efficiency, the SP signal offers horizontal positioning accuracy within 5–10 meters, vertical positioning within 15 meters, a velocity vector measuring within 10 cm/s.
- The more accurate HP signal is only available for authorized users, such as the Russian military.
GLONASS Coverage
- The constellation operates in three orbital planes, with 8 evenly spaced satellites on each.
- A fully operational constellation with global coverage consists of 24 satellites, while 18 satellites are necessary for covering the territory of Russia.
- To get a position fix, the receiver must be in the range of at least four satellites, three of which will be used to determine the user's location and the fourth to synchronize clocks of the receiver and the three other spacecraft.
GLONASS Availability
- Current GLONASS constellation satellite locations:
- Instant Positional Dilution of Precision (PDOP) values (ALT ≥ 5°):
- Integral availability (PDOP≤6) for previous 24 hour period (ALT ≥ 5°):
Do I Need GLONASS?
- Many modern GPS receivers (GPSr) are able to use both GLONASS and GPS satellites simultaneously.
- GPS + GLONASS provides greatly improved coverage and quicker time to fix due to having more than 50 satellites available.
- For indoor, urban, canyon or mountainous areas, accuracy can be greatly improved over using GPS alone.
