US Patent 8044839 Combined radar and communications link

In a CW radar system for detecting motion behind a wall involving modulation of the radar transmission, means are provided to interrupt the CW wave when motion is detected and to use the same radar transmitter to transmit a serial digital message to a remote monitoring receiver. The encoding can include a receiver wakeup message to turn on the receiver only when motion has been detected. In one embodiment, a microprocessor is used to detect when motion exists behind a wall and to provide a tailorable message to modulate the radar's transmitter in the period when the CW signal from the radar is turned off after motion detection.