Target Detection Method In Passive Bistatic Radar Based On Beidou ? Satellite Signals

The passive radar performs well in the performance such as anti-interference,anti-raid,anti-destruction,anti-stealth and so on,which uses the communication,broadcasting and satellite signals as the non-cooperative signals.Among them,the passive radar based on satellite signals has many advantages.This kind of signal is an important research direction of the passive radar because it is far away from the ground,covering a wide area and all weather.With the improvement of the Beidou Navigation Satellite System and the safety in wartime,it is important to use the Beidou satellite signal as the illumination source.Since the Beidou I in the Beidou Navigation Satellite System has been discontinued,and the Beidou III is being erected,this paper uses the Beidou II satellite signal as the illumination source.The paper mainly studies the signal processing method of target detection based on the external radiation source radar system of Beidou II satellite signal.Firstly,This paper introduces the composition and working principle of the Beidou Navigation Satellite System,and analysis the advantages of the Beidou satellite signal as the illumination source and the composition and fuzzy characteristics of the Beidou II satellite signal.On the basis of this work,the main research contents of the thesis are as follows:1.Beacuse of the low transmission power of the satellite and the possibility that all satellites may use the same carrier frequency,the reference signal received by the Passive Bistatic Radar Based on Beidou II Satellite Signals is not pure.In addition,target echoes in the echo channel are often contaminated by components such as direct waves and multipath clutter.The other components in the reference signal and the echo signal have a bad impact on the coherent accumulation results.So the reference signal and the echo signal need to be processed before the target detection.According to the characteristics of the Beidou II satellite signal,this paper proposes a signal reconstruction method for purifying the reference signal.Then,several time-domain filtering algorithms are analyzed and compared.And the ECA-B algorithm is used to suppress the clutter components such as direct wave and multipath clutter in the echo signal.Finally,the distance-Doppler coherent detection is performed on the reference signal and the echo signal.2.Since the satellite is far from the ground,it is often necessary to increase the signal accumulation time in order to improve the signal-to-noise ratio of the signal during target detection.When the target is in motion,extending the coherent accumulation time causes problems of distance walking and Doppler diffusion,resulting in dispersion of energy.Aiming at the walking problem of the distance unit,this paper proposes to combine the time-sharing filtering method with keystone transform and frequency domain compensation method,and proves the effectiveness of the proposed method by simulation experiments.Aiming at the problem of Doppler diffusion,the method of reconstructing phase error is used to compensate Doppler diffusion and verified by simulation experiments.