Improved Pseudorange Smoothing Method for Standing Multipath Mitigation

摘要

In satellite-based augmentation system (SBAS), because of limited satellite-station geometry change, some multipath interference varies very slowly and repeats at a time shift from several hours to one day. To mitigate the interference in real time, which is needed in Augmentation System, the code noise and multipath (CNMP) method was proposed, where the smoothed pseudorange is used to estimate the "standing" multipath. But some experiments show that the left error still looks with the same periods as original multipath. An improved pseudorange smoothing method is proposed to eliminate the left error. Firstly, the differential equation about the left error and the standing multipath is deduced, which can be solved to get the exact expression of the standing multipath. Following the formula, the corresponding real time filtering procedure is designed by modifying the CNMP method. And the experiments show that the proposed method can actually cancel the periodic component in the standing multipath.