직선배열 hydrophone에 의한 수중음원의 분석

Directive Spectrum Analyzing System Using a Linear Hydrophone Array

길이 250cm, 간격 10cm의 25개의 수동계 직선배열 hydrophone을 0, $\pm1$의 거형파 weighting을 부가하여 신호와 weighting과의 convolution을 구하고 이것을 동기가산하는 방법으로 얻는 방향검출과 spectrum분석은 그 실현방법을 증대시키고 정현파 weighting을 부가하는 것보다 3dB정 도 낮으나 지향성을 준 방향보다 타방향의 spectrum성분의 Power level을 적어도 16dB 정도 이상 억제할 수가 있었다. 또 신호까지 0, $\pm1$의 거형파로 바꾸는 경우는 전술한 성분을 적어도 8 dB 이상 억제할 수 있었다.

The direction and spectra of underwater sound wave were a remarkable contrast to the sound wave in the air because of the difference of transmissive medium. The linear hydrophone array of passive system has so far been applied to find out the direction and spectra of underwater sound wave from the sources for many purposes. The conventional methods are generally classified into two systems such as, the system which varying frequency responses, other parameters and pattern of signal like an adaptive array controlled by internal feedback, and another system which obtaining maximum of S/N ratio by giving a appropriate delay and a weighting coefficient in the output of each hydrophone. The array device of passive system can easily change the amplitude and the phase of signal by separately controlled hydrophone. And here we introduce a method that the spectral analyzing and the direction finding can be simultaneously carried out using a linear array of hydrophones. By making a circular convolution of output of signal from each hydrophone with appropriate rectangular weighting coefficient on the array, a sharp response of single lobe directivity and the spectral analyzing by time averaging were simultaneously obtained. In tile computer simulation of the array system with the length of 250cm and the interhydrophone distance of l0cm the power levels of sound signals received from given array direction were 16dB higher than those from the other directions when processing with rectangular weightings, and 8dB higher when processing with rectangular sound signals and rectangular weightings.