A Multipath Elimination Algorithm Combined with MEDLL Loop and Hatch Filtering

摘要

Multipath error is the main source of error affecting the accuracy of modern satellite navigation receivers. The MEDLL algorithm can effectively reduce the multi-path error by estimating the multipath parameters and is an effective multipath elimination technique in the baseband signal processing stage. However, in the scenario where the number of multipaths is large or the change is fast, the parameters cannot be fully estimated. The result is a large multipath residual, which in turn affects the multipath resistance. Carrier phase smoothing pseudorange (Hatch filtering) has good effect on improving the statistical characteristics of pseudorange and further eliminating multipath error. It is a commonly used pseudorange preprocessing method for measurement receivers and various differential enhancement systems, but its performance is very dependent. The choice of smoothing time. In this paper, a joint algorithm is proposed to estimate the multi-path in the MEDLL loop to control the smoothing time of Hatch. The algorithm is based on carrier phase tracking error and multipath error constraint. Compared with traditional fixed smoothing time Hatch filtering in multipath interference. When the residual is large, the effect is better, and at the same time, the defect of insufficient multipath elimination of the MEDLL algorithm in some scenarios is compensated, so that the multipath elimination in different stages of the receiver is more sufficient and effective.