| 摘要 |
PURPOSE:To make it possible to execute automatic range switching when memorizing and indicating wave-receiving signal in a fish-detecting equipment, etc., by detecting a seabed signal and holding in memory of a signal of depth range in which the seabed signal exists. CONSTITUTION:A wave transmitting/receiving unit 1 transmits an ultrasonic pulse into water on the basis of a trigger a formed every cycle T of a transmitting trigger generating circuit 2, and at the same time, it receives reflected wave. An amplified signal b of an amplifying circuit 4 is treated by A-D conversion 4 and memorized by a memory circuit 5. A signal read out from the circuit 5 is treated by D-A conversion 6 and indicated on such an object as a CRT 7. A seabed detecting circuit 8 slices a signal b at a level Vo and detects a seabed pulse C1 by a seabed signal B1. An FF13 is changed to high level by the pulse C1. A frequency-dividing pulse generating circuit 11 divides frequency in proportion to the cycle T based on the change of detecting depth range. Therefore, content of memory of the circuit 5 is always selected within a limit of signal of depth range containing the seabed signal. |
