Patent US 5,581,297

If motion occurs in an area viewed by a lens (14) of a video camera (12), a video security monitoring system (10) establishes a communication link with a video monitoring facility and begins transmitting compressed video images of the area. The system (10) is fabricated from CMOS integrated circuits, and operates at a reduced clock frequency while motion is not detected. Reducing the clock frequency lowers the required power thus permitting operation of the system (10) on energy supplied by an ISDN basic access communication channel. If motion occurs, a digital video image compression subsystem (16) begins producing low quality compressed video data for transmission to the monitoring facility. If motion occurs in the central region of the area viewed by the lens (14), then the subsystem (16) produces a single high quality compressed video image. Commands transmitted from the monitoring facility to the video security monitoring system (10) may control its entire operation.