| With the development of acoustic stealth technology, the noise and target strength of underwater target significantly reduced, and the sonar operating range is decreasing accordingly. Because of the separable resource and receiver, multistatic sonar inherits advantages of active sonar many special advantages in underwater target detection and localization, such as target independent, known signal wave form shape, also keep the characteristic of passive sonar, such as good stealthiness,, long operating range. By research on the new sonar mechanism, the relocations of multistatic sonar , Time Delay Estimation method, the method of the suppression of direct wave interference and multiple access interference are detailed studied in this thesis.Operative mode and performance of multisttic sonar are determined by its overall configuration. Based on 2D target location circumstance, detective performance and four basic operative modes are studied, and affection on sonar positioning accuracy at different parameters and error distribution maps are also given, respectively. Besides, this thesis analysis geometric configuration of the multistatic sonar which have influence on the effects sonar positioning accuracy,Time Delay Estimation methods are absolutely necessary for multistatic sonar. A TDE method based on spectrum zoom is adopted in this thesis, which is equivalent in performance but robustness to the traditional correlation method.The key problem in multistatic sonar is multiple access interference and strong direct wave interference, which must be solved. The algorithm of interference suppression are researched and analysised under multistatic circumstance. Conventional adaptive beam forming method offers a certain effectiveness in incoherent multiple access interference, but ineffectiveness in coherent illumination. By using a least square method under zeros constrain, strong direct wave and multiple access interference are effectively solved.
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