Performance Assessment of Non-Integer-Hour Data Blocks in BDS Broadcast Ephemeris

Due to system anomalies, BeiDou navigation satellite system (BDS) sometimes updates the broadcast ephemeris at non-integral hours. The gross errors contained in the non-integer-hour data blocks of broadcast ephemeris will lead to the signal-in-space (SIS) anomalies of BDS satellites, and then affect the SIS continuity and availability performance of BDS satellites. In order to study the performance of non-integer-hour data blocks in BDS broadcast ephemeris, a gross error identification method for BDS non-integer-hour broadcast ephemeris based on precise ephemeris has been proposed in this paper to identify the 2017–2021 BDS non-integer-hour broadcast ephemeris data into gross error data blocks, normal data blocks and unknown data blocks. For the normal data blocks in BDS non-integer-hour broadcast ephemeris, the orbit performance and clock performance have been assessed in detail. And then, the judgment conditions for the normal data blocks and gross error data blocks have been further studied. The research results show that the normal data blocks of BDS non-integer-hour broadcast ephemeris satisfy the relationship of TOC(time of clock)-TOE(time of ephemeris)=720Ns (N=1, 2, 3 and 4), while the gross error data blocks satisfy the relationship of TOC-TOE
$\ne 720$
Ns (N=1, 2, 3 and 4).