| 摘要 |
<p>An ultrasonic ranging device for use in a vehicle having a high frequency oscillator supplying continuous sine wave signals to a power amplifier through a first gate controlled by a timer. A second gate controlled by the timer supplies an amplified sine wave signal from the power amplifier to a piezoelectric transducer mounted on an exterior portion of a vehicle. The transducer produces a series of repeated ultrasonic pulses and receives echoes from nearby objects converting the echoes into electrical return signals. A receiver amplifies the return signals and supplies them to a coincidence gate, which is enabled for relatively short time intervals by a timer. The coincidence gate supplies an output signal to an indicator when the return signal is detected during the interval that the gate is enabled.</p> |
