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Functional Segments of GNSS
Published in Basudeb Bhatta, Global Navigation Satellite Systems, 2021
In December 1995, the full constellation of GLONASS satellites was completed and the system was declared operational. Unfortunately, following the financial and political crisis in the Soviet Union (now Russia), the GLONASS constellation could not be maintained, and the number of operational satellites decreased dramatically to only seven in 2002. In addition, the lifetime of the satellites (3 years, compared to 10 years for the GPS satellites) exacerbated this situation. To keep the system operational, numerous launches had to be made, which led to more financial difficulties. However, in October 2011, it was fully restored. This was achieved progressively by maintaining the constellation at a minimal level and successively adding new satellites, improving the lifetime and performances of the GLONASS-M satellites, and developing new smaller GLONASS-K satellites in order to deploy a full 24-satellite constellation of both GLONASS-M and GLONASS-K for domestic and international availability. GLONASS-M satellites have a longer service life of 7 years (GLONASS had 3 years’ life) and are equipped with updated antenna feeder systems. The main feature of the GLONASS-M satellites is the transmission of a new signal for civilian use in L2. The life span of GLONASS-K is about 10–12 years; and a third civilian frequency (L3) has been added. Russia has a plan to have a total of 30 (instead of 24) satellites, 10 in each orbital plane with two of them to be used as operating reserves (spares).
Positioning and Tracking Approaches and Technologies
Published in Hassan A. Karimi, Advanced Location-Based Technologies and Services, 2016
Dorota Grejner-Brzezinska, Allison Kealy
Similar to GPS, GLONASS is also part of a modernization program where the GLONASS-M satellites first launched in 2003 now broadcast civilian codes on both the L1 and L2 frequencies. The first GLONASS K satellite launched in 2011 is undergoing testing of the transmission of a third signal L3 that will offer the same benefits as the GPS L5 signal. GLONASS K satellites will also use CDMA (as well as continue to use FDMA) signals to simplify combined receiver design and to facilitate compatibility with other GNSS. The GLONASS control segment comprises the System Control Centre located in Moscow and the telemetry and tracking stations located across the Russian territory. The GLONASS control segment performs tasks comparable to those of the GPS control segment.
Electronic navigation and vessel reporting systems
Published in G.D. Lees, W.G. Williamson, Handbook for Marine Radio Communication, 2015
The space sector consists of 24 operational satellites (8 in each of three orbital planes) at altitudes of around 19,100 kilometres, inclined at approximately 65° with an orbital period of 11 hours 15 minutes. In addition, 2 spare SVs are available. Each satellite broadcasts its precise position and, to lesser accuracy, the position of other satellites in the constellation. Improved satellites Glonass-K1 and K2 will begin launching in 2022 and Glonass-KM by 2025 using frequencies and formats used by GPS, Galileo, and Beidou SVs. This will facilitate better integration of receivers using signals from all four GNSS satellites and bring the GLONASS constellation up to 30 operational SVs.
Satellite delivery of high-accuracy GNSS precise point positioning service: an overview for Australia
Published in Journal of Spatial Science, 2019
The first GLONASS-K satellite launched in 2011 transmits CDMA signals, in addition to the system’s legacy FDMA signals, to improve the interoperability with other GNSS. Of particular interest is the new GLONASS L3 CDMA signal centred at 1207.14 MHz, sharing the same frequency as the Galileo E5b signal in the protected aeronautical frequency band. A PPP service is also planned for transmission on Russia’s System for Differential Correction and Monitoring (SDCM) satellites on the L1 and L3 GLONASS bands by 2018, enabling high-accuracy positioning and navigation services (Stupak 2013).