Design and implementation of a BDS precise point positioning service
Precise point positioning (PPP) service is of great significance for BDS. The design and implementation of the service are presented. The PPP-B2b signal of the service is constructed, which is efficient multiplexed with other signal components, and achieves compatibility between two service phases. A customized message format that can augment all visible satellites of four core constellations in mainland China is proposed. The high-gain, 64-ary, low-density parity check (LDPC) coding is used, which facilitates the integrated design of the receivers. A signal quality test has revealed that the S-curve bias (SCB) of PPP-B2b does not exceed 0.0165 ns and the coherence between the code and the carrier of the signal is only 0.137 degrees. A performance evaluation has indicated that at its current stage, the positioning accuracy in the horizontal and vertical directions is better than 0.15 m and 0.3 m, respectively, and the convergence time does not exceed 800 s.