A new method based on QSE processing for interferometric GNSS-R ocean altimetry

Abstract

Considering that in conventional GNSS-R (Global Navigation Satellite System-Reflection) altimetry, the reflected signals are cross-correlated with a locally generated clean replica of the transmitted signal, interferometric processing consists of the measurement of the complex cross-correlation between the direct and reflected signals. It allows the exploitation of P(Y) code and other civil signals to maximize the height estimation precision. This paper presents a new processing method called QSE (Quadrature Staggered Extracting) which utilizes P(Y) code to explore a further improvement of the altimetry precision. The assessment of the QSE processing procedure illustrates GPS L1 band as an example. In these conditions, this paper analysis the up-looking SNRs obtained by using QSE processing and traditional coherent demodulation respectively. The analysis of the altimetry precision shows that the results obtained by adopting QSE processing improve by a factor about 1.15 as compared to the results obtained by using coherent demodulation.