Applications of satellite laser ranging and laser time transfer in BeiDou navigation satellite system

Abstract

BeiDou navigation satellite System (BDS), was the dedicated Chinese Global Navigation Satellite Systems (GNSS). The satellites in the BDS constellation can be tracked by many Satellite Laser Range (SLR) stations, making use of the onboard Laser Retro-reflector Array (LRA). Additionally, some of BDS satellites were also equipped with Laser Time Transfer (LTT) payloads. The measuring data from these instruments provided highly accurate estimations of satellites orbit, and time comparison between satellites and ground clocks.The performance of the BDS LRA and LTT payloads designed by Shanghai Astronomical Observatory (SHAO) were presented, as well as the SLR systems with a one meter-aperture telescope, which provided the ranging precision of centimeter levels for daylight ranging to BDS satellites at the synchronous orbit. For the first time, high precise LTT measurements at the synchronous orbit satellites were performed by the SHAO. The LTT data processing and analysis were presented with the time stability of 20ps at 500s, and a relative frequency stability of 10E-14.The further developments and improvements of Chinese LTT technology were also discussed. Global SLR tracking of BDS satellites were performed by the International Laser Ranging Service, providing accurate range data with global coverage. By using laser data, the accuracy of BDS satellite orbit and broadcast ephemeris were evaluated and the orbit error of BDS satellites was achieved at the meter level.