Motion detector based on the doppler principle

摘要

A motion detector based on the Doppler principle contains a microwave module for emitting a microwave signal containing at least two frequencies into a room under surveillance and for receiving the radiation reflected from the latter. An evaluation stage is connected to the microwave module and generates first and second Doppler signals from the received radiation. The first and second Doppler signals have a phase difference which is proportional to the distance of an object reflecting the microwave signal. The phase difference is determined by an integral transformation. In addition, the relative size of an object and the direction of travel of an object reflecting the microwave signal can be determined by the evaluation stage.