The Effect of DCB Correction on Multi-system Combination Precise Point Positioning

The satellite differential code bias (DCB) characterizes the time it takes for the signal to travel from the reference clock to the transmitting antenna. The internal delay of the signal can be up to ten nanoseconds, and the pseudorange can be up to the meter level. It must be corrected when high-precision point positioning. This paper analyzes the DCB correction formulas of different pseudorange combinations of GPS and BDS. Using GPS, GPS + BDS, GPS + GLAONASS + BDS and iGMAS released DCB products, standard single point positioning (SPP) and precise point positioning (PPP) solutions are performed for multiple stations in China. The results show that after DCB correction, the SPP accuracy is improved in decimeters, the average improvement rate of the three schemes is about 30%. The static PPP accuracy has a millimeter-level improvement and the accuracy is improved by about 10%. DCB correction has the greatest impact on the positioning of single GPS system. However, when multi-system combination positioning is performed, the influence of DCB correction on positioning accuracy is weakened, the improvement rate is greatly reduced, and the coordinate precision improvement of some stations is sub-millimeter.