METHOD OF DETECTING A RADAR CHARACTERISTIC, A RADAR CHARACTERISTIC DETECTION APPARATUS, AND A RECORDING MEDIUM RECORDING DATA FOR DETECTING A RADAR CHARACTERISTIC

A radar wave reflected by a preceding automotive vehicle is received. The distance and the reception level of the received radar wave are repeatedly stored with relation therebetween. The reception levels are plotted with respect to distance. The distribution of the receptions levels is approximated with a linear equation as the characteristic of the radar apparatus. Variation in the distribution, that is, Y intercept of the linear equation represents the variation of the characteristic of the radar apparatus. A reference characteristic of the radar is measured with changing the distance to the preceding reflective object and the measured characteristic is measured with a moving preceding vehicle during actual traveling. The reference Y intercept is compared with the measured Y intercept to detect the deviation. Further, the divination amount or the measured value is classified to judge the cause of decries in the characteristic using conditional signals.