Vehicle anti-collision radar - avoids false danger alarms from reflections from roadside reflectors

摘要

An instrument for the determination of the differential velocity and the distance of an object in front of a moving vehicle uses a centimeter wave pulsed signal and a receiver for the returned echoes, whith an evaluation circuit determining the distance from the time difference between transmitted and returned signals from the distance signals, together with a further differentiator followed by a threshold switch which cuts out the main differentiator if the output of the additional differentiator exceeds a pre-set value. The effect is to prevent a false warning of excess speed if a temporary flse echo is received from a close roadside reflecting object.