Realization And Performance Analysis Of Interferometry Phase Detection Algorithm In Multibeam Bathymetry System

Multi-beam echo sounder is a kind of efficient and accurately sea bed surveying instruments. It is developed on the basis of the single beam, and it is very suitable for massive sea floor surveying. Multi-beam echo technique could be applied to various kinds of circumstances in the field of underwater detection, and it has great prospects, researches on the key techniques in multi-beam bathymetry are very important, and have strategic meanings to the ocean resources survey and exploiting for our country.Because of the disadvantages of traditional amplitude detection method and instant zero phase detection method, the thesis mainly studies the technique of multi-beam interferometry phase detection. When this technique is used, it is needless to form hundreds of beams because less beams can provide the same information. The technique can be applied to resolve the depth of the Multi-beam swath, and the result suggests that this algorithm cost less computation time, while the estimated result is more accurate, so it could be used in the application of sea bed surveying. This thesis mainly include the below four major study items.The theory of interferometry and the key technique are introduced in detail. In this thesis, the key factors to interferometry are analyzed. According to the analysis of phase, we get the conclusion that continuous beam output can get continuous DOA estimation. And then, we use the algorithm of using less instead of traditional beam-form algorithm that use hundreds of beams, which reduces the operation loads greatly, and thereby establishes the foundation for the quick phase detecting.For the fundamentality of phase difference in the algorithm, the factors which can influence phase difference accuracy are analyzed. After the analysis of DOA estimation accuracy, we can get the conclusion that it has a close relationship with the distance between adjacent sub-arrays. In order to get the least phase error, the method of choosing the optimizing baseline is specifically studied.Because of the ambiguity of the phase difference will be introduced ,the method of choosing the optimizing baseline is used, we introduce the Vernier method to study the related algorithm removing this ambiguity. Nowadays, we always detect just one echo wave in multi-beam echo sounder and does not accord with the real environments. This thesis studies and realizes an algorithm to detect multiple targets which are from the same direction.At last, the thesis describes the key steps of the algorithm, and then the lake experiment data are used to verify the efficiency of the algorithm. And the results suggest that the algorithm proposed in the dissertation is right and feasible.