GNSS satellite yaw attitude laws and impact on satellite clock, phase OSB and PPP-AR

Abstract

Satellite yaw attitudes have significant impact on Global Navigation Satellite System (GNSS) data processing in two ways: the satellite horizontal phase center offset (PCO) corrections and phase wind-up corrections. When the Sun elevation angle is small, GNSS satellites are unable to maintain the nominal attitude and take place the yaw maneuvers. Generally, different types of satellites adopt different yaw attitudes during the yaw maneuver periods. In this research, the yaw attitude laws of different types of GPS, Galileo and BDS-3 satellites are comprehensively investigated, and the impact of yaw attitudes on satellite clock, phase observable-specific signal bias (OSB) and precise point positioning with ambiguity resolution (PPP-AR) are deeply evaluated. The main results show that for GPS Block IIF satellites, the maximum differences between the nominal yaw angles and the modeled yaw angles can reach to 360°. With the nominal attitude, the estimated phase OSB changes approximately 1 cycle and a 10 cm bias is observed in the U component positioning solutions of kinematic PPP-AR. After applying the modeled attitude, these obvious errors disappear. In addition, for BDS-3 SECM satellites, the mismodeling of the nominal attitude and CSNO modeled attitude results in 4–6 cm jumps in the detrended satellite clock residuals, and a 40 cm bias is observed in the U component positioning solutions of BDS-3 kinematic PPP-AR. After applying the modified CSNO modeled attitude to BDS-3 SECM satellites, the stability of satellite clocks and the positioning accuracy of PPP-AR are significantly improved.