| 摘要 |
<p>PROBLEM TO BE SOLVED: To detect the influence that a deposit on the surface of a transmission/ reception antenna has on the output of a transmission wave accurately and to provide a means for eliminating the deposit properly by detecting a target based on a beat signal that is synthesized with a reflection wave from an object with a relative speed for the transmission wave and a vehicle. SOLUTION: A reflection wave that is transmitted from a transmission/ reception antenna 28 and is reflected from, for example, a target of a preceding vehicle is received by an antenna 28 and is supplied to a mixer 32. The mixer 32 synthesizes a transmission wave from a directivity coupler 18 and a reflection wave from a circulator 24 and generates a beat signal. The beat signal includes a component that fluctuates due to the difference between the frequency of each component and the modulation frequency of the transmission wave and has a strength according to that of each component. The beat signal that is amplified by an amplifier 36 is supplied to a signal-processing part 10, the relative distance and relative speed between each target and the vehicle are calculated based on each kind of beat frequency, and a means for eliminating the influence of a deposit on the surface of an antenna is provided.</p> |
