Variation of the Incident Sound Level at the Underwater Target`s Position due to Roll Motion of the Ship

선체의 횡요로 인한 수중물표입사음압의 변동에 관하여

  • Published : 1983.06.01

Abstract

As the first step to investigate the effect of ship's motion when detecting target with an echo sounder, variations in the incident sound level at the optional position within the sound beam due to roll motion of the transmitter have been measured and calculated. In this experiment, the transmitter (75 KHz) was mounted to the bottom of a FRP model of the 2,275 G. T. stern trawler and the receiver (75 KHz) was installed at each measuring point within the transmitter's beam. Then, the incident sound level was measured for the roll angles from the free roll test on the model ship. For a range of roll angle of $\pm$20$^{\circ}$from the vertical, the measuring values of the incident sound level at each measuring point were rapidly fluctuated from 12.9% to 78.1 depending on the roll angle, and agreed well with the caculated ones. Consquently, we concluded that the effect of ship's motion when detecting target with an echo sounder should be sufficiently considered.

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