High Resolution DOA Estimation Techniques For Underwater Coherent Signals

As an important part of the array signal processing, high-resolution direction of arrival estimation technique has a promising perspective in many fields such as radar and sonar, with the development of the microelectronic and digital techniques. High-resolution algorithm aimed at narrow and independent signals at first, but in underwater signal processing, coherent signals exist here and there because of the spread of multiple path, dispersive phenomena and the influence of the bottom and surface of the sea.How to use high-resolution algorithm for coherent signals is a difficult question for underwater signal processing. Aiming at the practical applications on engineering, the dissertation studies the theories and methods of the coherent signals .The main results and achievements are summarized as follows:1.The classic and high-resolution theories of space spectrum are discussed. High-resolution algorithms such as MUSIC, Mini-Norm and ESPRIT are analysed according to the characteristic decomposed,and the steps of the algorithms are gived too. The estimate function and the actual value of the algorithm are analysed through simulation.2.The theories and methods of the narrow coherent signals are studied. The common techniques for getting rid of coherent, such as space smoothing, vector revise, modified MUSIC,Toeplitz method and space filter are discussed. Through simulation, the estimation precision, distinguish probability, threshold of the ratio of signal to noise(SNR) and the robustness of the algorithm are compared .The results show space smoothing has good performance in high SNR circumstance , Toeplitz method and modified MUSIC have excellent performance in low SNR circumstance .3.The modified algorithms based on space smoothing are lucubrated.The beamspace algorithm and propagator method are disserted systemic. Relative to element space,beamspace has lower operation quantity and better robust function, and the operation quantity of the coherent algorithm gets down also because of propagator method. The modified algorithms based on space smoothing under low SNR circumstance are discussed at the same time, the research results show matrix decomposition,cross correlation and weighted space smoothing have better performance than space smoothing. Further more, combining MUSIC algorithm and...