Evaluation and calibration of BeiDou receiver-related pseudorange biases

Abstract

The pseudorange observation of the BeiDou satellite navigation system (BDS) reveals some special errors. Except for the elevation-dependent code bias variations, we present receiver-related code biases of BDS. We have analyzed the BDS receiver-related code biases based on observations from 257 stations whose receivers are from seven different manufacturers. The results demonstrate that BDS code biases are related to receiver manufacturers and receiver models and that they can reach up to about 3.0 ns among different receiver types. Moreover, BDS receiver-related code biases are quite stable over a long period of time. There is no doubt that when mixed receiver types are used, the BDS receiver-related code biases will affect the accuracy of data processing, e.g., satellite differential code bias and satellite clock bias estimation. Thus, to correct BDS receiver-related code biases, correction models for different receiver types are established. Three experiments, including satellite clock estimation, single point positioning (SPP) and pseudorange residual analysis are carried out to validate the corrections proposed. The results prove that, with BDS receiver-related code biases corrected, the biases of satellite clock estimated by mixed receiver types are more consistent with those estimated by the same receiver types. Compared with results without code bias corrections, the average satellite clock bias decreases from 1.04 to 0.22 ns which is an improvement of about 78.8%. Moreover, the accuracy of the ionospheric-free SPP is improved by 7.3 and 10.0% on average in vertical and horizontal components, respectively. The percentage of pseudorange residuals distributed between − 0.5 and 0.5 m is improved from 49.8 to 53.2%.