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A Research Of Interference Signal Detection And Suppression Methods Based On Frequency Diverse Array Radar

Posted on:2020-11-15Degree:MasterType:Thesis
Country:ChinaCandidate:C PanFull Text:PDF
GTID:2428330596976044Subject:Communication and Information System
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Modern radar and communication systems cannot exert better performance due to the effect of electromagnetic interference signals.The diversity of interference signals also brings new challenges to traditional detection and suppression methods.The emergence of the concept of frequency diversity arrays responds to such demands.This method establishes frequency diversity by introducing a small frequency to adjacent array elements to slightly carrier frequency shift,and creates new fields to the processing of interference signals.This thesis studies the detection and suppression methods of interference signals.The main contents are as follows:In order to solve the interference signal problem caused by multipath propagation,this thesis applies FDA to microwave links in a simple multipath propagation environment,and built a multipath propagation model using electric field model,and established a theoretical framework for analyzing its performance with time average power as its metric.Besides,the thesis proves that traditional phased arrays and frequency arrays have large differences in average received power,and FDA has potential advantages in mitigating the harmful effects of multipath propagation.Then,aiming at the problem that the difference of average received power is not obvious under a certain frequency shift,the average received power curve smoothness model is proposed.Meanwhile,the influence of the frequency shift parameter on the smoothness is summarized.A single-parameter frequency offset optimization method is proposed.Finally,we proposed a genetic algorithm based frequency shift optimization method,breaking through the original linear incremental relationship,improving the smoothness optimization rate to 58% based on the traditional linear incremental frequency offset.Therefore,effectively improves the accuracy of detection and the FDA's advantages in multipath propagation.To handle the suppression of interference signals,in this thesis,a multi-antenna receiving system with frequency array is proposed.And the frequency array is tested to be of better robustness to noise signals.The conventional method known as MVDR has also been applied to the frequency array,and MVDR beamforming algorithm model of the frequency array is proposed.Using the semi-positive relaxation algorithm combined with the phase-only beamforming algorithm to deal with the optimization problem of the output signal-to-noise ratio by expending the domain and transforming the non-convex multimode problem into a convex optimization problem.And the output of signal-to-noise ratio can be improved to some extent by diagonal loading.Compared with the performance of the MVDR beamforming algorithm,the new method has better output signal-to-noise ratio,when the angular separation between the interference and the desired target is too small,it will also result in the formation of deeper nulls than the MVDR beamforming algorithm.Simulation results show that the proposed interference signal detection and suppression method based on FDA can achieve the accurate suppression of multiple different interference signals,and the performance is far better than the conventional beamforming algorithm.
Keywords/Search Tags:frequency diverse array, average received power, genetic algorithm, semi-positive relaxation, beamforming
PDF Full Text Request
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