UNDERWATER DETECTION SYSTEM

摘要

The present invention is directed to provide an underwater detection system which can determine frequency components contained in echoes arriving from all azimuthal directions at high speed and enhance target discriminating capabilities by presenting such frequency components. The underwater detection system rotates a pair of ultrasonic receiving beams having a fixed phase angle difference, measures phase differences between two signals picked up by both ultrasonic receiving beams, determines carrier frequencies contained in target echoes from the phase differences, derives magnitudes and directions of moving velocities of targets from the carrier frequencies, and displays such target data in different colors. Furthermore, it provides such information as over-the-ground velocities of targets themselves upon compensating target velocity data with ship velocity data.