Initial Assessment of BDS Zone Correction

BDS Satellite-Based Augmentation Service Correction Parameters and Performance Assessment

“…In addition to the above-described corrections, the BDS SBAS broadcasts the partition comprehensive correction parameters, which are used for the correction of residual errors of orbit/clock and regional environment corrections (mainly tropospheric residuals) [7,[19][20][21]. The PCC parameters are basically the Observation Space Representation (OSR)-based corrections and are used to correct carrier-phase observations.…”

“…As shown by Chen et al [7,19] and Zhang et al [20], the new BDS SBAS corrections are generated in a superimposition way: In the first step satellite, orbit/clock corrections are estimated in an iterative way; and the estimated real-time orbit/clock corrections are then used to correct the orbit/clock errors in the broadcast ephemeris during the second step where the PCC is estimated for each satellite/partition pairs.…”

“…It is worth noting that the BDS broadcast clocks are referred to the B3 frequency, the timing group delay (TGD) parameters should be applied [23] in the dual-frequency ionospheric-free combination. Meanwhile, as the partition comprehensive correction contains most parts of tropospheric residuals within a certain area, it is recommended that there is no necessity to estimate the residual tropospheric delay considering the accuracy requirement of decimeter level [19,20].…”

“…Partition comprehensive correction is the most unique SBAS corrections as broadcasted by BDS [8,20]. As an example, Figure 5 shows the real-time partition comprehensive corrections of C01, C06, and C11, in partition No.…”

“…The tropospheric delay was corrected using the SHAtropE model [27] and GMF mapping function [28], which were identical to the processing model of BDS GCS. It should be noted that the rest of the wet tropospheric delay was not necessary to be estimated as a random walk parameter since the PCC contains tropospheric model error and this part of the error would be modelled very well in areas near the partition center [20]. The BDS IGSO and MEO phase observation precision was set to 0.005 m and the priori precision of code observation was set to 0.5 m, while for GEO satellites, they needed to be down-weighted due to the worse accuracy of GEO orbits and clocks [29,30].…”