Image Processing Based Radio-frequency-interference Suppression For High Frequency Passive Bistatic Radar

Based on DRM digital shortwave broadcast,High Frequency(HF)passive bistatic radar uses non cooperative digital broadcasting signals to detect and track targets.As a useful supplement of active radar,it can provide a new way for our country's strategic early warning,land air defense and marine rights and interests maintenance.HF passive bistatic radar works in the congested short band of frequency band,so it will be affected by radio frequency interference(RFI).The reference channel and surveillance channel will be interfered by RFI,which affects the detection performance of radar on the two-dimensional spectrum.Based on the analysis of the characteristics of RFI on the two-dimensional spectrum of HF passive bistatic radar,this paper puts forward the detection and suppression method of RFI based on image processing on the basis of the research of existing RFI suppression algorithms of signal processing.The specific contents are as follows:(1)The influence of RFI on HF passive bistatic radar is studied,and the commonly RFI suppression methods based on signal processing are summarized.According to the signal processing flow and waveform characteristics of HF passive bistatic radar,this paper analyzes the characteristics of RFI on the range spectrum of HF passive bistatic radar,and puts forward the idea and plan for detection and suppression of RFI based on image processing.(2)Aiming at the problem of detecting RFI of HF passive bistatic radar,an image processing method is introduced to detect RFI from range spectrum.First,the direct wave and strong multipath clutter in the received signal are suppressed,then the range spectrum with RFI is preprocessed by edge detection algorithm,finally the range spectrum contaminated by RFI is judged.(3)Aiming at the problem of suppressing RFI of HF passive bistatic radar,in order to solve the problem that the traditional signal processing methods are not sufficient to suppress RFI,the image processing method and the signal processing method are combined;the image roughness index is used to evaluate the RFI suppression performance of the subspace projection algorithm in range spectrum in order to obtain the optimal RFI suppression performance.