Estimation of differential code biases for Beidou navigation system using multi-GNSS observations: How stable are the differential satellite and receiver code biases?

Differential code biases (dcbs) are important parameters that must be estimated accurately and reliably for high-precision gnss applications. for optimal operational service performance of the beidou navigation system (bds), continuous monitoring and constant quality assessment of the bds satellite dcbs are crucial. in this study, a global ionospheric model was constructed based on a dual system bds/gps combination. daily bds dcbs were estimated together with the total electron content from 23 months’ multi-gnss observations. the stability of the resulting bds dcb estimates was analyzed in detail. it was found that over a long period, the standard deviations (stds) for all satellite b1–b2 dcbs were within 0.3 ns (average: 0.19 ns) and for all satellite b1–b3 dcbs, the stds were within 0.36 ns (average: 0.22 ns). for bds receivers, the stds were greater than for the satellites, with most values $$<$$ 2 ns. the dcbs of different receiver families are different. comparison of the statistics of the short-term stability of satellite dcbs over different time intervals revealed that the difference in std between 28- and 7-day intervals was small, with a maximum not exceeding 0.06 ns. in almost all cases, the difference in bds satellite dcbs between two consecutive days was $$<$$ 0.8 ns. the main conclusion is that because of the stability of the bds dcbs, they only require occasional estimation or calibration. furthermore, the 30-day averaged satellite dcbs can be used reliably for the most demanding bds applications.