Impact of Receiver Dynamics on Space-Based GNSS-R Altimetry

Abstract

It is a challenge to achieve high accuracy altimetric results using space-based global navigation satellite system reflectometry (GNSS-R). This paper focuses on improving the accuracy of space-based GNSS-R altimetric measurements by considering receiver dynamics in the geometric model. The receiver dynamics has negligible impact on the geometric model of low-platform GNSS-R because the receiver movement is quite small during the time period between receiving direct and reflected signals. However, in the case of space-based GNSS-R, the receiver has much higher dynamics, thus the receiver dynamics cannot be ignored. This paper analyzes the altimetric error caused by the receiver dynamics in space-based GNSS-R. Theoretical studies and simulations were conducted to evaluate the magnitude of the altimetric error caused by receiver dynamics. The results show that the dynamics of a low earth orbit receiver can lead to errors of the order of several meters, depending on the trajectory angle of the receiver. The results using data from the TDS-1 mission conclude that neglecting receiver motion causes an average error of 3.4 m. This agrees with the result obtained from a theoretical analysis. Therefore the geometric model that takes into account receiver dynamics can improve the accuracy of space-based GNSS-R altimetric measurements of the order of a few meters compared to neglecting receiver dynamics.