Image Number 10 for United States Patent #6903678.
A vehicle radar system extracts peak frequencies fbu and fbd of respective beat signals B1 to B9 representing the frequency difference between a transmission signal fs and a plurality of received signals fr1 to fr9. The phase difference of respective beat signals B1 to B9 at the peak frequencies fbu and fbd is converted into a frequency signal. In the case of reflection from a close range road surface or raindrops, the phase difference of each beat signal is irregular. The peak frequency intensity of a converted frequency signal is small. This system compares the peak frequency intensity of the converted frequency signal with predetermined criterion intensity. Then, the system identifies an objective with a close range road surface or raindrops when the peak frequency intensity of the converted frequency signal is not larger than the predetermined criterion intensity.