| 摘要 |
<p>PROBLEM TO BE SOLVED: To control the time constant of an integrating circuit depending on the distance to a target by integrating a receiving signal for a preset time using an analog switch and an integrating circuit. SOLUTION: A pulse signal transmitting means 1 transmits pulse signals at a constant interval and receives 2 a reflected wave from a forward target. A sampling means 4 conducts a switch with a gate signal at an interval corresponding to a constant distance and samples the receiving signal before delivering to a variable integrating means 11. The receiving signal is outputted only for a preset time after a pulse signal is delivered based on the gate signal, and the means 11 integrates the receiving signal at an initially set time constant before outputting the integrated receiving signal. When the switch is not conducting, the integrated output is sustained. The integrated output signal is subjected to A/D conversion 6 and a decision means 7 measures the voltage at each sampling point and detects a peak value of receiving signal thus calculating the distance. When the time constant is increased (decreased) depending on the calculated distance, a voltage generating means 12 increases (decreases) the voltage.</p> |
