摘要 |
The invention solves a problem of fluctuation in performance in the conventional peripheral monitor for monitoring periphery of a vehicle that measures a distance to other vehicle or any other object by transmitting radio waves and informs a driver of the distance due to variation in environmental conditions such as water drop sticking onto the cover. A peripheral monitor 1 including a transmission antenna 2 for radiating transmission waves through the cover, a receiving antenna 3 for receiving reflected waves through the cover, and a data processor for measuring a distance to any object are disposed together in a cover 7. A transmission frequency at which reflected wave quantity is minimized is detected by detecting a first reflected signal level from the cover 7, and this frequency is a command to a variable frequency oscillator to conduct a transmission at this frequency at all times.
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