PARIS — The Russian government is preparing a major upgrade to is Glonass positioning, navigation and timing network by doubling the number of ground stations providing system validation via geostationary-orbit satellites and boosting the number of satellites connected to them.
The upgrade also includes the launch of six elliptical-orbit Glonass satellites to augment coverage in the Eastern Hemisphere, with launches scheduled between 2023 and 2025.
Ivan Revnivykh, head of the Glonass applications division of Russia’s Roscosmos space agency, said Russia’s Glonass overlay, called the System for Differential Correct and Monitoring (SDCM), has completed testing for its initial capacity and is now being certified.
The current network uses three Luch satellites in geostationary orbit, at 167 degrees East, 16 West and 95 East longitude. The ground network includes 19 stations in Russia and six in other nations.
SDCM is similar to geostationary-orbit overlays employed for the U.S. GPS, European Galileo and Chinese BeiDou satellite navigation systems. The main constellations operate in medium-Earth orbit (MEO).
Revnivykh told the March 25-27 Munich Satellite Navigation Summit that the current Glonass constellation 24 MEO-orbit satellites, plus one in-orbit spare and one that as of late March was in flight testing.
the network provides 100% availability in Russian territory and 99.99% coverage in the rest of the world.
The SDCM upgrade starting in 2020 will feature new satellites launched into the geostationary-orbit slots at 16 West, 95 East and 167 East, plus a new satellite at 160 West, he said.
Integrity verification messages are sent to users within six seconds. The network upgrade will not improve the current horizontal accuracy but will sharpen vertical and 3D positioning accuracy.
Overall Glonass accuracy now is listed at 1 meter. Supplemented by several thousand ground-based reference stations in Russia, the system is capable of 3-centimeter accuracy, and 1 centimeter for a high-precision service for automated transport systems and precision engineering.
To improve coverage in urban canyons and other places with obstructed views of the MEO constellation, Russia is launching six new Glonass satellites into three orbital planes inclined at 64.8 degrees relative to the equator. The satellite are scheduled for launch, two at a time, aboard Angara-A5 rockets from Russia’s Plesetsk and Vostochny cosmodromes.