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The Technique Of Suppressing Towed Body Noise Using Vector Sensor Line Array

Posted on:2014-03-12Degree:MasterType:Thesis
Country:ChinaCandidate:P X DouFull Text:PDF
GTID:2272330479979435Subject:Underwater Acoustics
Abstract/Summary:PDF Full Text Request
The conventional towed line array sonar has two key problems in practice use: the array aperture is too long and the port/starboard ambiguity problem. The vector sensor with the advantages of spatial directivity and spatial gain can solve these two problems perfectly, so the vector sensor has a good application prospect. But both general towed line array and vector towed line array, when in actual use, have to undergo the crucible of complex ocean noise environment. In the marine environment, the towed body radiation noise is one of the key factors of towed line array sonar detection performance, and the noise characteristic is very complex, so far there is no ideal method of interference suppression. In order to ascend towed line array sonar weak target detection performance and reduce the detection blind area, you must suppress such this noise.Based on vector towed array as the background, this paper tries to find a way which can restrain the noise interference of the towed body effectively, mainly done the following work:The time-frequency and spatial characteristics of towed body radiation noise are studied. The noise propagation model of the towed body is established; The effects of towed body noise to the directional performance of the towed line array under the condition of shallow sea is analyzed, by analyzing the test data, further verify that the tugboat noise makes towed line array sonar on the beam direction exists detection blind area in a range of angles, could cover up the weak targets at the same time.Based on the analysis of the vector hydrophone and towed body noise characteristics, this paper put forward two kinds of towed body interference suppression techniques. The first one is the adaptive interference cancellation method using a vector sensor array, this method uses the characteristics of the coherent interference of vector hydrophone, the adaptive filter order need to be very small, has a relatively low computation; The second one is the vector array towed body noise image beam subtraction method, it uses "cardioid" directivity of the joint signal processing of vector sensor using both sound pressure and velocity, the interference noise can be completely suppress. Gives the evaluation criterion of the performance of the towed ship noise suppressing method, and on the above two methods are compared. Both are suitable for broadband noise suppression, all have good interference suppression effect, and can ensure that the vector array port/starboard gain not be decreased. But the second method, its realization is more simple, just need very small amount of calculation, the noise interference can be completely suppressed theoretically; and is suitable for the unstable random signal; do not need steady-state time of the adaptive algorithm.The vector sensor towed array interference suppression method is put forward, which will further improve the performance of target detection, orientation and positioning of vector sensor array, promote the development of the application of vector sensor array.
Keywords/Search Tags:Vector Sensor Array, Noise Canceling, Left right discrimation, Adaptive Signal Processing
PDF Full Text Request
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