JPS5550176A - Method of underwater detection - Google Patents

Abstract

PURPOSE:To accurately detect an object without being affected by interference, by picking out only the first half part of a received signal and recording the picked-out part. CONSTITUTION:Ultrasonic pulses are radiated from a transmitter receiver and reflected on an underwater object. The reflected pulses are received by the transmitter receiver, the output of which is amplified by a pre-amplifier so that a signal (b) is produced. The signal (b) is applied to a phase correlator. The signal (b) and another signal delayed by a half period thereto are superposed with each other so that a correlation output (d) is produced. The output (d) is applied to a delay circuit to generate a delay circuit output (e). These outputs are added to each other by an analogue adder so that a signal (f) with the pulse width of the radiated waves is generated. The signal (f) is amplified by a low frequency amplifier and then recorded on recording paper (s) by a recording pen (p). If there are a plurality of reflected signals and the phase delay of each reflected signal is not less than a half period, only the half parts of the reflected signals are reproduced with the original pulse width, namely, with information on their levels.