Characteristics of Other GNSS Systems
All of the global systems operate in a very similar manner to the GPS system, but each has its own unique qualities:
- GLONASS – Operates in the L1 band similar to GPS, but uses a Frequency Division Multiple Access (FDMA) signal where each satellite transmits at a slightly different, higher frequency than GPS. Their orbits are optimized for slightly better accuracy at the northern latitudes, but the system still offers complete worldwide coverage. Originally a relic of the Cold War, the entire constellation was updated and is fully operational with modern equipment since 2011.
- Galileo – Uses more modern modulation than GPS, operating in three bands: E1, E5 and E6, and offers an encrypted Public Regulated Service and enhanced Search And Rescue (SAR) service. Eighteen satellites are operational today, the fully operational constellation is expected by 2019.
- Beidou (formerly called Compass) - This system is operational regionally over Asia today, but new satellites are being launched to offer full worldwide coverage by 2020 with 37 satellites. The new signal structure is very similar to Galileo and the new GPS signals.
- QZSS – A regional navigation satellite system for the East Asia and Oceania region, operated by the Japanese Government. This system is used in combination with data from other GNSS satellites and as such is not operational by itself.