The Study Of Localization Technology Of VHF/UHF Band Radar Narrowband Radio Frequency Interference Signal Source

Ultra-wide-band(UWB)synthetic aperture radar(SAR)/ground moving target indication(GMTI)system working in very high frequency(VHF)/ ultra high frequency(UHF)band has the ability of targets imaging and detection,so it is widely applicated in military and civil field.But the radio and television signals will go into the receiver with radar echoes,forming the radio frequency interference.It plays a very important role in reducing the influence of radio frequency interference and improve the quality of imaging for UWB SAR operation.Especially when the narrowband RFI signal's energy is much greater than the target echo's,the dynamic range of the receiver will be greatly reduced.The normal work of the SAR/GMTI system can be influenced seriously.In order to avoid this kind of jamming signals effectively,we need to locate the interference sources.Based on foliage penetrating radar,the article studies how to locate sources of VHF/UHF band narrowband radio frequency interference with UWB SAR/GMTI system.The main work is as follows:1.In the problem of locating narrow-band radio frequency signals,we need to determine the parameters of the jammings firstly.Actually it can be regarded as a problem of estimating sinusoidal signal parameters.Based on the study of classical parameter estimation method,this paper proposes a sine wave parameter estimation method of local refinement search in frequency domain using FFT and cosine transform algorithm(CTA).The measured data simulation proved the accuracy and effectiveness of the algorithm.2.Based on signal parameter estimation,the article studies multi-stations passive location method.It can use the phase differences of GMTI channels to estimate the arrival angles of RFI and locate the interference sources with bearing-crossing locating method.The simulation results and the measured data processing results show the effectiveness of the proposed method.3.Based on signal parameter estimation,the article studies passive location method of single mobile station.Firstly,it regards the moving main channel as a linear array and estimates the arrival angles of RFI with Doppler frequency.Then it locates the interference sources with bearing-crossing locating method.The results of simulation experiments proved the effectiveness of the method.The technology of locating and related algorithms in this article has been successfully applied in RFI source locating and the evasion of jamming signals.