PURPOSE: To improve the reliability of the peak pair of frequency modulation radar equipment so as to eliminate the possibility of erroneous measurement.

CONSTITUTION: A first pairing means M2 pairs peaks having high correlation by calculating the correlation between the peak of one power spectrum of either the rising part or falling part of a frequency and the peak of the other power spectrum. A peak pair selecting means M3 selects the peak having the highest opposite correlation with the single peak of the other power spectrum out of the multiple peaks of the spectrum by calculating the opposite correlation between the single peak and multiple peaks when the means M3 pairs the multiple peaks of the power spectrum with the single peak of the other spectrum.