关键词: 星地差分GPS, 地基测控系统, 相对位置精度因子, 实时标校, 半实物仿真

Abstract:
Abstract： In view of the shortcomings of traditional calibration methods and the differential GPS based post-calibration method for ground-based TT&C systems, a real-time calibration method based on satellite-to-ground differential GPS was proposed. Compared with the differential GPS based post-calibration method, the real-time calibration method enables the ground-based TT&C systems to obtain the calibrated measurement data in time to carry out orbit determination and prediction in real time and to timely inject the orbit parameters to improve the operational performance of the satellite. In view of the long baseline, high dynamic and real-time satellite-to-ground calibration scenario, all kinds of errors affecting the performance of satellite-to-ground baseline estimation and the correction effectiveness of these errors were systematically analyzed, and the concept of relative position dilution precision was proposed, thus obtaining the accuracy budget of satellite-to-ground baseline estimation. A robust adaptive Kalman filter algorithm was used as the real-time satellite-to-ground baseline estimation algorithm, and a weighted least square method was employed to solve the real-time measurement error of the ground-based TT&C system, so as to obtain the calibration results. A hardware-in-the-loop simulation platform was established by using spaceborne dual frequency GPS receivers and a navigation signal simulator. The simulation results show that, after real-time calibration, the residual ranging error of the TT&C system is reduced to about 40cm, and the residual velocity measurement error is reduced to less than 1cm/s, which is consistent with the theoretical analysis, and can well meet the requirements of future space missions.

Key words: satellite-to-ground differential GPS, ground-based TT&, C system, relative position dilution precision, real-time calibration, hardware-in-the-loop simulation