Intrusion detecting apparatus for a vehicle

摘要

An intrusion detecting apparatus for a vehicle comprises: a doppler shift signal outputting unit for outputting a doppler shift signal in response to a reflected and received ultrasonic signal from an ultrasonic receiver and a transmitted ultrasonic signal from a transmitter, an envelope detecting circuit for detecting the level of the received ultrasonic signal, and a detecting means for detecting an illegal intrusion by a person only when it is determined that the doppler shift signal is within a predetermined amount corresponding to the movement of a person intruding into the passenger compartment and it is also determined that the detected level of the received ultrasonic signal is out of a range of a disturbance, whereby an erroneous detection due to a disturbance caused by some reason other than an intrusion can be prevented.