Enhanced Range Doppler Mapping Algorithm for Passive GNSS based radar Rerial Target Detection

Abstract Passive GNSS based radar is a developing non-contact and emerging remote sensing technology in recent decade. However, due to the problems of weak signal and low resolution, the application of such technology in remote sensing application is very limited. This paper considers GNSS based radar detection of air object, and puts forward the signal-to-noise ratio improvement scheme of range doppler map (RDM) to improve the detection ability. In this paper, bi-static GNSS radar model is employed. The RDM of air target is obtained on the basis of direct and reflected signals. The proposed RDM SNR (signal-to-noise ratio) improvement algorithm mainly uses the autocorrelation characteristics of GNSS code to purify and reduce the noise of GNSS signal, so as to improve resolution of RDM and accuracy of target motion state solution. Compared with the current noise reduction method, which mostly depends on the prior conditions such as background environment, the proposed algorithm is more applicable, as it is mainly based on the characteristics of the signal. The RDM image is obtained by simulating moving target detection.In the condition of input signal CNR(Carrier-to-noise ration) is 35dB, the algorithm shows that the image information entropy after noise reduction is 63.23% for GPS signal and 71.69% for Beidou signal which lower than that before noise reduction.