FM-CW radar system for measuring distance to and relative speed of target

An FM-CW radar apparatus for a vehicle comprising:

• a radar wave transmitter transmitting a radar wave having a frequency modulated so as to increase at a given rate and decrease at a given rate cyclically;
• a radar wave receiver receiving a return of the radar wave from a target object present in a radar detection zone to mix the return of the radar wave with the radar wave transmitted from said radar wave transmitter to produce a beat signal;
• a peak frequency component producing circuit analyzing the beat signal in frequency to produce peak frequency components in a modulated frequency-rising range wherein the frequency of the radar wave transmitted from said radar wave transmitter increases and a modulated frequency-falling range wherein the frequency of the radar wave decreases;
• and
• a radar data producing circuit producing radar data, if one of peak frequency pairs, each of which is made up of each of the peak frequency components in the modulated frequency-rising range and one of the peak frequency components in the modulated frequency-falling range, lies within a given lower frequency range, said radar producing circuit identifying the one of the peak frequency pairs as the radar data arising from a moving object appearing suddenly in the radar detection zone.