The BeiDou Navigation Satellite System (BDS) is a Chinese satellite navigation system.
Unlike the American GPS, Russian GLONASS, and European Galileo systems, which use medium Earth orbit satellites, BeiDou-1 used satellites in geostationary orbit. This means that the system does not require a large constellation of satellites, but it also limits the coverage to areas on Earth where the satellites are visible. The area that can be serviced is from longitude 70° E to 140° E and from latitude 5° N to 55° N. A frequency of the system is 2491.75 MHz.