| 摘要 |
PURPOSE:To provide an ultrasonic transmitter-receiver which is constructed so that the service life of an ultrasonic sensor is prolonged, the measurement accuracy is secured during rainy days, and affect of standing waves due to obstacles is eliminated, by switching an ultrasonic transmitter and ultrasonic receiver. CONSTITUTION:A anemometer comprises a pair of ultrasonic transmitter- receivers 2 and 3 provided on the bottom or ceiling, etc., of a vehicle. In a control circuit 9, when a detection signal is outputted by either of left- and right-side obstacle detection sensors 4 and 5, one side where an obstacle exists in the transmitter-receivers 2 and 3 is set on the transmitting side, while the other side is set on the receiving side. In addition, the circuit 9 switches the transmitter-receivers 2 and 3 to the transmitting or receiving side alternately based on the detection signal issued from a rain-drop sensor 6. Further, the circuit 9 estimates switching timing for the transmitting and receiving timings by detecting the receiving level of the transmitter-receivers 2 and 3. |
