Dimension-separated DOA Estimation Algorithm For Anti Mainlobe & Sidelobe Interference

Interference suppression has been a primary problem of source locating and tracking, in view of the sidelobe interference, using a variety of principles and methods of adaptive beamforming technology has excellent inhibition effect. However, when the interference has access to the main beam, common sidelobe interference suppression methods will form a deep nulling in the mainlobe, leading to the offset of main beam pointing, a severe distortion of main beam shape, the elevation of sidelobe level, thus having great impact on DOA estimation precision and tracking accuracy.With the existence of mainlobe interference, this thesis focuses on the mainlobe/sidelobe interference suppression and DOA estimation algorithm based on the planar phased array, the main research contents are outlined as follows:Firstly, the mainlobe interference suppression and pattern reshaping algorithms have been studied under plane array. For the situation that general adaptive beamforming methods will deteriorate the performance of beams, combined preprocessing technology, adaptive beamforming with pattern reshaping technology, three kind of mainlobe interference suppression and pattern reshaping methods are introduced. By doing the preprocessing before the adaptive beamforming, the direction of mainlobe interference should be estimated firstly, and then the mainlobe interference need preprocessing according to the estimated information, after that in order to ensure the performance of beams and maintain beams shape after interference suppression, various pattern reshaping means should be added to common adaptive beamforming methods. Simulation experiments analyze and illustrate the above various algorithms.Secondly, the interference suppression and pattern reshaping algorithms have been studied by using dimension-separated of planar array. Combined dimension-separated processing technology with the mainlobe interference suppression technology, a dimension-separated adaptive interference suppression algorithm is proposed. The planar array is equivalent to two uniform linear arrays of azimuth and elevation dimensions with dimension-separated and adaptive technology, so the process of two uniform linear arrays is equivalent to deal with the entire planar array. Block matrix or adaptive beamforming is used for mainlobe or sidelobe interference suppression, at the same time use pattern reshaping method to reshape to the main beam, so as to ensure the inhibition effect of interference suppression while maintaining the performance of the main beam. Simulations demonstrate and analyze the performance of interference suppression and the effect of pattern reshaping.Finally, a dimensionality reduction four-channel GSC interference suppression and DOA estimation algorithm has been studied. On the basis of sum channel, elevation difference channel and azimuth difference channel, a double difference channel is added to form four channels. Combined four-channel adaptive monopulse with GSC, a dimensionality reduction four-channel GSC interference suppression DOA estimation algorithm is proposed. For large plane phased array, dimensionality reduction is achieved by subarray division, the interference block matrix of four channels are constructed after sum-difference beamforming. The sidelobe interference are suppressed by making use of four-channel GSC; then under the circumstance of one dimension(elevation dimension or azimuth dimension)is certainly non adaptive, another dimension(azimuth or elevation dimension)use adaptive sum-difference beamforming to anti interference, thus dimension-separated anti the mainlobe interference. Simulation results and performance analysis show that this algorithm has excellent effect in interference suppression and pattern reshaping, and has high estimation density.