Array Shape Estimation Of Long Onshore Hydrophone Array Based On Time Delay Estimation

Applications of hydrophone arrays are limited by the error of array shapes. The principle of array shape estimation based on time delay estimation is analyzed, which is a robust method of high precision, compared to direct measurement based on sensors and match-field inversion approaches.First of all, various methods of time delay estimation are discussed. Then the basic theory of the single source method which makes use of the fixed inter-element distance as the actual inter-element distance approximately is proposed, as well as the double-sources method. The relative time delay in long horizontal line arrays can't be obtained simply by using only one element as a datum mark because of the vibration of horizontal correlations of acoustics. In the paper a partitioned time delay method which makes full use of high correlations between elements is presented for array shape estimation, it presents a reasonable method for sub-arrays based on CRLB boundary to reduce the passed error caused by the cumulating of errors between sub-arrays to the end of the arrays. After that, error models of single and double-source methods are developed and analyzed. In order to improve the accuracy, reasonable methods of how to dispose assistant sources are presented.At last, tests with data from sea trials showed that the proposed single source constrained by fixed inter-element distance method can be applied in practice compared with the double-sources method when the bend of the array is not too large. And the partitioned time delay method presented above meets the need for distance between elements and decreases the error as well. In a word, the methods developed in this paper meet the need for the study of long hydrophone arrays, so they are of great importance in the application of long hydrophone arrays and array shape estimation.