The Research Of Weak Signal DOA Estimation In The Presence Of Strong Interference

At present, the weak signal detection and parameter estimation method of arrayantenna technology is widely used in territory of military or national economy suchas:radar, communication, navigation, sonar, radio astronomy, biomedicine engineeringand earthquake detection and so on. While, as the complexity of actual workenvironment, datum received by array antenna simultaneous existence of the weakexpected signals and strong interference signals, which lead to the estimation of classicDOA（DOA, Direction of Arrival） method, such as multiple signal classification(MUSIC) and rotation invariant subspace method (ESPRITE) method can notaccurately detect the weak signal, thus the weak signal direction of arrival estimationaccuracy of the system is greatly influenced. To solve these problems, this paper makesthe research as follows:Firstly, the method to solve the estimation problem of weak signals DOAestimation that in the presence of strong interference is summarized, then the paper putsforward two algorithms–one is jam jamming method based on Householder transform,the other is corrected projection jam method which based on the traditional classicalMUSIC algorithm.(1)The basic idea of Householder transform is use the known or canbe accurately estimated wave direction information construct interference blockingmatrix to pre-treat the receiving array signal, so as to estimate the weak signalaccurately.(2) The basic idea of corrected projection jam method is by constructingfeature decomposition of the array covariance matrix, use the subspace theory to findthe interference subspace, and make orthogonal projection matrix interference subspaceas interference blocking matrix, then pre-treat the received array signal, so as to achievethe purpose of suppressing interference. That is to say, two methods that are all constructed by means of interference blocking matrix to block interference; but themethod of constructing blocking matrix is different, the corrected projective blockingmethod does not require strong accurate interference information. The results ofsimulation were carried out with MATLAB7.0.Secondly, Simulation and experiments were respectively carried out to comparethe performance between the existing algorithms and the algorithms proposed by thispaper, according to the evaluating indicators(the number of interference angle, differentarray model, different number of array element, different intensity signal from differentangle, array amplitude and phase errors) respectively. The simulation results show that,the proposed algorithms can accurate estimate the weak signals DOA from strong noiseinterference. The algorithm has the advantages of fixed blocking matrix form, and issuitable for one-dimensional or two-dimensional. The method based on Householdertransform blocking is no need to pre-whitening processing, therefore it obviouslyreduced calculate complex.While the modified corrected projection jam method haveoutstanding performance even under the numbers of the interference and don’t lostdegrees of freedom..