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GLONASS Future and Evolutions
| GLONASS | |
|---|---|
| Title | GLONASS Future and Evolutions |
| Author(s) | GMV |
| Level | Basic |
| Year of Publication | 2011 |
In 2001, there were only seven GLONASS operational satellites in orbit. Acknowledging that navigation satellite system GLONASS was a top priority, the Government of the Russian Federation, by its Decree No. 587 of 20 August 2001, approved a Federal Task Program on the Global Navigation System (GNS) [1]. The GNS Program covers improvement of space, ground-based and user equipment segments of the GLONASS system.
One of the main objectives of the Program is to ensure GLONASS performance similar to GPS by the end of 2011. GLONASS poorer performance is the culmination of several factors:[2]
- poorer on-board atomic clocks
- less stability and predictability in the satellite orbits (and therefore less accuracy in GLONASS broadcast ephemerides)
- fewer satellites providing signals
- operational control and ground monitoring segment limited to Russian territory,
The Program is scheduled to end in 2011, however the Federal Spacy Agency has already announced that the maintenance and development of GLONASS will be extended until 2020, and will cost 402 billion rubles ($14.35 billion).[3]
Signal Modernization
Traditionally, GLONASS satellites transmits navigational radiosignals on two frequency sub-bands (L1 ~ 1602 MHz and L2 ~ 1246 MHz), relying on the Frequency Division Multiple Access (FDMA) technique in contrast to CDMA employed by all the other GNSS systems.
Aiming to provide better accuracy, multipath resistance and especially, greater interoperability with GPS and future GALILEO and other GNSS Systems, new GLONASS-K satellites will transmit CDMA signals in addition to the system’s traditional FDMA. In fact, since the successful launch of the first GLONASS K1 satellite, [4], a new L3 CDMA signal is already being transmitting and tracked by several receiver companies. The GLONASS L3 signal is centered at 1207.14 MHz, the same frequency as Galileo/COMPASS signal E5b, in the region allocated to the Aeronautical Radio 1 Navigation Service (ARNS). These bands are especially suitable for Safety-of-Life applications because no other users are allowed to interfere with their signals.
The future GLONASS K2 satellites to be launched in 2013, will feature three additional CDMA signals near the original FDMA frequencies, one obfuscated signal located at 1242 MHz in the L2 band, as well as two signals at 1575.42 MHz in the L1 band.
A modernized GLONASS-K satellite, GLONASS-KM, for launch after 2015 [5] may also transmit on the GPS L5 frequency at 1176.45 MHz, the same as the modernized GPS signal "Safety of Life" (L5) and Galileo signal E5a.