| 摘要 |
PROBLEM TO BE SOLVED: To provide an ultrasonic range finder which achieves a measurement from a short to long range. SOLUTION: There are arranged a reverberation/infiltration cancelling gate 1 for ultrasonic waves, a monitoring gate 2 covering the same the length of time with the cancelling gate 1 as generated after the end of the cancelling gate 1, a monitoring gate 3 covering the same length of time with the cancelling gate 1 as generated after the end of the monitoring gate 2 and a long range reflected wave monitoring gate 4 as generated after the end of the monitoring gates 2 and 3. When a reflected wave at a short range happens to enter within the length of time of the cancelling gate 1, the distance is calculated at time intervals between the reflected wave following the secondary wave and the subsequent reflected wave thereof. |
