Application of USBL in low frequency array directivity measurement
As the frequency of the underwater acoustic transducer decreases,the laboratory space is difficult to meet the requirements of free-field and far-field measurement.However,and the underwater environment in open water is relatively complex,so it is difficult to achieve deep lifting of the array.Therefore,it is necessary to equip an expensive lifting platform to obtain the standard sound source and the relative pose of the array to be measured,which has low efficiency and high maintenance cost.In this paper,the ultra-short baseline positioning technology is adopted,and the linear frequency modulated pulse signal and the pseudo random coded pulse signal are selected as the signals.The distance and phase measurement are realized based on the pulse compression method and the complex correlation algorithm respectively.The results of comparison of the positioning accuracy test on the lake and the static test of array directivity calibration show that the angle error is within 2.5°.The measurement error of-6 dB beamwidth is within 5.38%in the frequency range of 2-10 kHz.It proved the feasibility of ultra-short baseline positioning in low frequency array directivity calibration.
ultra-short baseline(USBL)directivitytransducelinear frequency modulated pulse signalpseudo random binary sequence pulse signal
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