Direction of travel motion detector with automatic gain control

摘要

Disclosed is a microwave direction of travel detector and method of doing the same. The microwave direction of travel detector comprising, a microwave transceiver for transmitting and receiving a microwave signal directed toward a protected area for outputting a Doppler signal when a moving target is detected, an amplifier chain including one or more amplifiers coupled to the microwave transceiver for receiving and amplifying the Doppler signal from the microwave transceiver, wherein at least one amplifier having variable gain and; a controller for sampling an output gain of each variable gain amplifier and for controlling each variable gain amplifier by adjusting a gain of each variable gain amplifier to keep the Doppler signal level constant and to avoid saturation of each said variable gain amplifier. If the output gains of each variable gain amplifier is increasing or decreasing the controller indicates a direction of travel.