| 摘要 |
The present invention is an electro acoustic target searching system comprising receiving transducer means capable of receiving first, second and third frequencies, signal evaluation means for producing direction signals indicative of direction of reception of acoustic signals at any of the frequencies and logic means operable to control the frequency at which the evaluation means determines the direction of reception so that if a direction signal determined from evaluation at the lowest frequency exceeds a reference magnitude, evaluation is then made at the middle frequency, and if the resulting direction signals indicate receipt of acoustic signals exceeding a predetermined magnitude from a plurality of directions, evaluation is made at the highest frequency.
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