Research On Imaging Technique And Interference Suppression Of Ultra-wideband Random Noise SAR

Random noise radars have been investigated extensively over the past forty years. They were noted for their attractive LPI(low probability of intercept) and EMC(electro magnetic compatibility). By operating in the low VHF and UHF frequency bands, Ultra wideband synthetic aperture radar(UWB SAR) has been proven to be a very powerful tool that can penetrate the foliage(FOPEN) and ground(GPEN) to detect, image and discriminate the concealed targets. The combination of UWB SAR technology and random noise radar can gain significant benefits and overcome inherent individual drawbacks. Especially, with the increase of serve electronic jamming in modern war and service application, ultra wideband random noise synthetic aperture radar operating in VHF/UHF band could accommodate the complicated military and civil operating environment and creates a wide variety of potential possibilities for applications. The purpose of this thesis is to study the FOPEN/GPEN SAR using UWB random noise signal and the jamming suppression from theoretical aspect, which is detailed as following:1) Based on the analysis of UWB waveforms: linear frequency modulated(LFM), step-frequency, random noise, etc., the advantages of random noise are presented. In order to achieve the FOPEN/GPEN, the important system parameters are proposed.2) The unique features for UWB wide angle(WA) SAR imaging are indicated, with emphasis on the model of random noise radar based on the correlation receiver. The adaptive imaging algorithm, such as Range Migration Algorithm, is investigated and simulated in detail.3) By discussing the RFI and noise interferences on UWB random noise radar, we build models of several typical noise interferences and then analyze the interferences effects on UWB random noise radar by data simulations. Some evaluation methods are formed so that we can evaluate the result of jamming effects by the methods.4) For RFI and narrowband noise interferences, this dissertation studies notch filter and uses it to suppress narrow jammings in signal domain. The efficiencies of notch filter are validated by simulation experiments. We also evaluate the result of narrowband jamming suppression by the evaluation methods.At last, the whole thesis is concluded. And future work on the UWB SAR using random noise signal is pointed out.