The Research On Direction Finding Of Wideband Coherent Source

Direction finding with array is one of the important research areas of array signal processing.With the rapid development of modern signal processing technology,its scope of application is more and more wide,which involves the radar,communication,target detection,sonar,earthquake monitoring,biomedical,etc.Compared with the narrow band signal,wideband signal includes more information,which is beneficial to the detection of the signal source and the extraction of the target signal parameters.Due to the increasingly complex electromagnetic environment,a lot of signals with the same frequency or coherent sources appear at one time.Most traditional direction finding algorithms cannot process wideband coherent signals.Therefore,it is very important to study the direction finding of wideband coherent signals.Direction finding algorithms of wideband coherent sources are investigated extensively in the thesis.The mathematical model of uniform linear array and wideband coherent source are constructed,by which we study characters of wideband coherent sources and the problem of using the classical algorithm for direction finding.The direction finding algorithm of coherent signal is researched.An improved vector reconstruction method is proposed for the direction finding problem of multi group coherent signals.The algorithm selects the weighted eigenvector to construct a covariance.Then we use the conventional direction finding for direction finding.It can improve the signal direction finding performance under the condition of low single to noise ratio.The improved algorithm is simulated by MTALAB,and the simulation results verify the effectiveness of the algorithm.We discuss the direction finding algorithm of wideband source.The traditional method cannot estimate the DOA of wideband coherent signals when independent and coherent wideband sources coexist.For solving this problem,a novel direction finding algorithm of wideband source is introduced.The method separates the independent signals and coherent signal from the data covariance matrix.The DOA estimation of coherent sources can be obtained by using traditional direction finding algorithm,which effectively improve the utilization of the array.The effectiveness of the improved direction finding algorithm is verified by MTALAB simulation,and the simulation results are analyzed.The improved algorithm improves the success ratio of the direction finding at low single to noise ratio,and reduces the error of direction finding.