Methods and influence factors analysis of BeiDou DCB parameter solving based on regional monitoring networks

Through the use of intersatellite link data and ground regional networks, the BeiDou-3 system offers worldwide navigation, location, and timing services. Currently, the precision of the BeiDou-3 broadcast ephemeris orbit and clock offset products has reached a high level. However, due to insufficient satellite coverage from the ground regional network, the accuracy of the differential code bias (DCB) parameters broadcast by the satellites shows a significant gap compared to other navigation system parameters and post-processed precision products. In order to tackle these problems, this study examines how the accuracy of DCB parameter estimation in a regional monitoring network is affected by variables like the distribution of monitoring stations, multi-GNSS combinations, and ionospheric delay correction models. It proposes an optimal strategy for estimating DCB parameters within this network. Using the DCB products released by the Chinese Academy of Sciences (CAS) as a reference, the stability and consistency of the DCB products are analyzed, and their accuracy is evaluated through the signal in space range error (SISRE). Single-point positioning accuracy tests are conducted using BDS-3 B1I/B3I dual-frequency data. The findings show that, with a root mean square difference of roughly 0.4 ns, the satellite-end DCB stability in the regional monitoring network is roughly twice as poor as that of the satellite-end DCB determined using the CAS global monitoring network. The stability of satellite-end DCB calculated from dual-system observation data is superior, and the BDS-3 satellite DCB shows better consistency with the CAS DCB products. The receiver-end DCB in the regional monitoring network exhibits the same stability as the CAS DCB products, with dual-system observation data yielding better consistency for the receiver DCB. Compared to the SISRE results of BDS-3 calculated using TGD1 parameters from broadcast ephemeris, the regional monitoring network DCB products enhance the SISRE calculation accuracy for BDS-3 by 47.6%. The dual-frequency SPP positioning results improve by 14.1%, similar to the enhancement effect observed with the CAS DCB products.