Enhanced GNSS-SAR range-doppler algorithm for the target detection of weak reflected signals : an experimental study

Abstract

A new tool for remote sensing GNSS-SAR is developing recently. However, due to the limitation of narrow signal band of GNSS signals, images generated by GNSS-SAR are much noisy and with low azimuth resolution, particularly when reflected GNSS signals are weak. Due to the issue, a new algorithm is proposed for target detection based on the Range-Doppler algorithm in this paper. Firstly, according to the analysis of the average SNR (signal-to-noise ratio) of the received reflected signal, optimal threshold and range correlation duration are derived for detecting range compressed signal. Thereafter by properly scaling the detected range compressed signals along azimuth domain, we can further enhance the SNR along specified azimuth direction. Thus, when conducting azimuth processing, the azimuth resolution can be improved. In the paper, the new algorithms will be described and the experiment results will be presented.