Compass (Beidou in Chinese) is the name of the current Chinese Global Navigation Satellite System currently under development. China has indicated it intends to expand the current geostationary Beidou navigation system into a full medium-earth-orbit GNSS constellation.
Beidou/Compass actually comprises two systems. The first, known as Beidou 1, comprises three payloads on geosynchronous satellites. Beidou provides wide area precise positioning and is substantially a China-only system in terms of access and users. The Compass Navigation Satellite System or CNSS will be a true GNSS system comprising 30 MEO satellites orbiting the earth every 12 hours or so and providing true global coverage.
The constellation structure will be similar to the European Galileo network and the ranging signals are based on the CDMA principle, like GPS and Galileo. In line with other GNSS, there will be two levels of positioning service: open and restricted.
The Chinese have publicly stated the aim is “provision of Compass to provide free use all over the world”. At present, however, little information is available on Compass. The world is watching with interest for more information.
The ICD for the Compass system is not currently freely available. Spirent’s systems are “Compass ready” and if you have an interest in testing Compass please contact us.
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