Analysis of phase parameter equivalence and combined ambiguity reconstruction in GNSS-IR tide level retrieval

Abstract

Discrete phase jumps often occur when the Nonlinear Least Squares (NLS) algorithm is adopted to solve phase parameters of the SNR cosine model in GNSS-IR tide level retrieval. This paper analyzes the formation mechanism of phase jumps from the perspective of model parameter equivalence, and proposes a combined ambiguity reconstruction method based on robust reference center. Multi-constellation and multi-frequency observation data from SC02 and SPBY stations are used for experimental verification. The results show that the proposed method significantly improves the stability of the linear relationship between phase and retrieval error. The average RMSE of SC02 station decreases from 16.11 cm to 4.11 cm, which obviously enhances the tide level retrieval accuracy. The method effectively suppresses the multi-branch discrete effect caused by parameter equivalence, and provides a new solution for high-precision post-processing of GNSS-IR tide level retrieval.