Abstract: As an important part of GNSS navigation message, the differential code bias (DCB) parameter is one of the main error sources affecting the PNT services. COMPASS provides navigation signals on three frequencies, and broadcasts two TGD parameters. An algorithm to solve COMPASS satellites DCB parameters and their form error was introduced. According to the COMPASS tri-frequency characteristics, a new method using different dual-frequency combinations was proposed to evaluate the accuracy of DCB parameters. DCBs provided by manufacturers and DCBs solved by the algorithm are taken to analyze the effects on UERE and positioning accuracy. Real data analysis indicates that the form error of COMPASS satellite DCBs and GPS satellite DCBs share the same accuracy, however, influenced by the satellite constellation and regional distribution of stations, the stability of COMPASS satellite DCBs is worse than that of GPS satellite DCBs from IGS. The accuracy of COMPASS satellite DCBs is better than 0.5ns, and the difference of VTEC between different calculations using two kinds of geometric free combinations is better than 0.6TECU. Compared with DCBs provided by manufacturers, dual-frequency user′s 3D positioning accuracy is improved from 13.80% to 47.42% by using DCBs from the algorithm.

Key words: Differential code bias, Tri-frequency data, Accuracy assessment, COMPASS