| 摘要 |
PURPOSE:To make a predetermined depth allowance indicated by forming two window pulses associated with both ends of a sounding range of a sounding device and by making these pulse width adjustable. CONSTITUTION:A motor 10 is connected to an LED flusher circuit 12 and a one revolution pulse generating circuit 14. The one revolution pulse generating circuit 14 generates one pulse for every revolution of the motor 10. This pulse is sent to a transmission-reception pulse converting circuit 16 to cause a transmission timing of a transmitting ultrasonic pulse to be produced. A received ultrasonic pulse is given to a time constant circuit 18 via the pulse convertor 16. The time constant circuit 18 generates the first window pulse generated from timing of the transmitting ultrasonic pulse. A width of the window pulse is set freely with a adjustable setting means 20. The time constant circuit 30 provides the second window pulse. These window pulses are sent to a gate circuit 38. |
