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

摘要

An FM-CW radar apparatus is provided which may be employed in automotive anti-collision or radar cruise control systems. The radar apparatus transmits as a radar wave a high-frequency signal which is so modulated in frequency with a modulating signal as to vary with time in the form of a triangular wave and mixes a received signal with a local signal that is part of the transmitted signal to produce a beat signal consisting of a fundamental frequency component as a function of the distance to and relative speed of a target object. The radar apparatus also includes an amplitude modulator which modulates the amplitude of at least one of the transmitted signal, the received signal, and the local signal in accordance with the modulating signal so that the modulation index falls within a range of zero (0) to one (1). This allows harmonic components with an improved SN ratio to be extracted from the beat signal which may be used in calculating the fundamental frequency component of the beat signal.