Linearization of FM-CW Radar Sweep by Feedback.

A frequency-modulated radar is a radar in which a continuous-wave transmission is frequency modulated in a known manner in order to obtain range information. When the frequency modulation is linear with time, the difference between the frequency of the received signal and the transmitted signal is directly proportional to the target range. The difference frequency is given by 2Rcdfdt, R being the range to the target, c the velocity of electromagnetic waves and dfdt the slope of the sawtooth frequency modulation. Therefore, the difference frequency is proportional to both range and the slope of the modulated waveform.