Study On The Key Techniques Of Underwater Multiple Targets Direction-of-arrival Estimation

Multiple targets direction estimation technique is an important branch of underwater array signal processing, which development has great importance for underwater target location and tracking, and is also the key issue of enhancing underwater defense. Aiming at application in engineering, the key techniques of targets estimation are studied through algorithms analysis, simulation and water tank experiment. The main results and achievements are summarized as follows:1. Studied the theories of conventional and real-valued element-space algorithms, their performance was compared through simulation. The real-valued algorithms have less computational complexity, at the same condition they have high accurate and strong ability to resist noise, and can process correlate sources.2. Discussed the principles of beam-space algorithms, and studied the beam-forming matrix and the number of beams to the performance of algorithms. The conclusions are that DFT beam-forming matrix possess obviously advantage, and in low SNR for MUSIC and Root-MUSIC when the number of beams is larger than targets, the fewer the beams, the better the performance. For beam-space ESPRIT, the subarray should choose (M-1), so as to get better performance with low computational burden. For beam-space MODE, the number of beams should not too few.3. Aimed at the kind of peaks search algorithms, proposed a beams-space estimation method that based on peaks search. In order to reserve the advantage of conventional beam-forming system, proposed a estimation method that based on beam-forming system. Thereinto, the former does not need targets previous bearing information. The latter use the output of beam-forming system as coarse information, and then carry out fine estimation, which has the advantages of both beam-forming system and high resolution algorithm.4. Through the study of water tank experiment, obtain that the Channel unitizing Toeplitz error calibration method is effective. It can improve the performance of algorithms under array errors obviously, has great prospect in engineering. The water tank experiment demonstrates that in element-space, the calibrated Root-MUSIC, ESPRIT and MODE have low resolution threshold and good accuracy; in beam-space the calibrated Root-MUSIC, ESPRIT and MODE still have good performance.