Multi-mode Multi-frequency GNSS-IR Combination System for Sea Level Retrieval

Abstract

With the development of Global Navigation Satellite Systems (GNSS), geodetic GNSS receivers have been utilized to monitor sea levels using GNSS-Interferometry Reflectometry (GNSS-IR) technology. The multi-mode, multi-frequency signals of GPS, GLONASS, Galileo, and Beidou can be used for GNSS-IR sea level retrieval, but combining these retrievals remains problematic. To address this issue, a GNSS-IR sea level retrieval combination system has been developed, which begins by analyzing error sources in GNSS-IR sea level retrieval and establishing and solving the GNSS-IR retrieval equation. This paper focuses on two key points: time window selection and equation stability. The stability of the retrieval combination equations is determined by the condition number of the coefficient matrix within the time window. The impact of ill-conditioned coefficient matrices on the retrieval results is demonstrated using an extreme case of SNR data with only ascending or descending trajectories. After determining the time window and removing ill-conditioned equations, the multi-mode, multi-frequency GNSS-IR retrieval is performed. Results from three International GNSS Service (IGS) stations show that the combination method produces high-precision, high-resolution, and high-reliability sea level retrieval combination sequences.

Keywords

• |gnss-ir|sea level retrieval|multi-mode multi-frequency combination|equation stability