GNSS-IR Multi-satellite Combination for Soil Moisture Retrieval Considering Detection and Repair of Abnormal Phases

Low-quality SNR data usually cause abnormal phases in the fitting of non-linear least squares (LLS) algorithms. This is not conducive to the effective use of multi-satellite phases. In this paper, we proposed a retrieval method of SM based on multi-satellite combinations considering detection and repair of abnormal phases. Results indicate that with the coif5 wavelet, the satellite direct and reflected signals (compared to the traditional low-order polynomial) can be better separated. Combining the interquartile range and moving average filter can effectively detect and repair the abnormal phases, and further improve the quality of the phases for each satellite. Furthermore, each satellite phases represent SM information of different azimuths, and MSLR can fully combine the multi-satellite phases to improve the accuracy of SM retrieval