| 摘要 |
An obstacle detection system has multiple ultrasonic sonars. When a threshold value used for determining an existence of an obstacle is compared with a receiving signal having been amplified at a predetermined gain, the sonar having a receiving mode is provided with the gain which is higher than that of the sonar having a sending/receiving mode. Thus, the sensitivity of the sonar having the receiving mode can be improved so that a continuous sound field of the sonar is broadened. Accordingly, the distance of the border of the continuous sound field of the obstacle detection system from the vehicle can become substantially even.
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