New Algorithm for Multiple Object Detection in FM-CW Radar

A new practical algorithm is proposed for multiple object detection in automotive FM-CW radars. They are radars for ACC (Adaptive Cruise Control) radar, collision avoidance, pre-crash safety, side-object detection, etc. This algorithm can provide the distance and relative velocity of objects without the ambiguity of distance and relative velocity, an inherent problem of FM-CW. Since it is simple, straight-forward and fast, it is suitable for automotive application, in which the update time is less than 100 [msec]. This algorithm is based on two down chirp frequency sweeps with small slope-difference. Since the difference is small, the correct pairs of beat frequencies are obtained automatically. Because of the down chirps, the polarity of beat frequencies owing to the distance and the doppler becomes the same for an approaching object and then the distance and the velocity are uniquely determined. Namely the distance and velocity information for multiple objects can be calculated without the ambiguity in a simple manner.