Effects on dual-system interoperability performance with system time offset

One of the issuers encountered in dual-system satellite navigation is the time interoperability between pair of system. By displaying distribution of satellite visibility and PDOP within China,the virtue of BeiDou-GPS combination system is presented against either BeiDou or GPS individual navigation. With the description of the generation on BeiDou-GPS time offset(BGTO),two traditional approaches for BGTO is illustrated in attempt to eliminate the BGTO impact on the positioning,and a modified approach, which is based prepossessing pseudorange, is proposed.Further simulation to compare the accuracy on BeiDou-GPS positioning according to several working schemes which are the combination of approach for BGTO, survey user terminal, elevation cutoff, uncertainty of system time offset, as well as reference time. As a result,if the error of BGTO was maintained within 5ns, the proposed approach for BGTO shows plausible performance on the BeiDou-GPS district positioning.However, with the error of BGTO went beyond 5 ns, the traditional way for BGTO is able to provide better performance. Finally, a discussion on the selection of reference time is carried out and the result shows it is hardly to figure out a competitive reference time.There is further work on it.