Peripheral monitor for monitoring periphery of vehicle

A peripheral monitor for monitoring periphery of a vehicle comprising:

• variable frequency oscillating means that oscillates high-frequency signals of a commanded frequency;
• a transmitting antenna that is mounted inside of a cover disposed on a surface of the vehicle, and transmits high-frequency signals transmitting through the cover;
• a receiving antenna that receives reflected waves of the transmitted waves from any object;
• a receiving level analyzer that analyzes signal level of said reflected waves, discriminates between a first reflected signal of the transmitted waves reflected from the mentioned cover and a second reflected signal reflected from any object on the basis of the received reflected signals, and outputs data of receiving timing and a signal level of the first and second reflected signals respectively;
• and
• a data processor that processes the data and computes a distance to the object, and detects a frequency at which level of the first reflected signal is minimized and commands the mentioned variable frequency oscillator to oscillate at this frequency.