US Patent 9063225 High resolution Doppler collision avoidance radar

An example radar apparatus has a transmission frequency modulated by a chirp waveform having three chirp segments, including increasing, decreasing, and a constant frequency segments. The chirp waveform may extend over the full revisit time of the radar beam. The frequency difference between the transmitted and echo signals are determined at least once per chirp segment. Example apparatus include a Doppler radar for vehicle use.