Detector circuit for use in a VCR

摘要

Apparatus in accordance with the subject invention controls a cable box (i.e., the source of its own video input signals), and monitors the television signals received from the cable box, in a "closed loop" manner. By monitoring an appropriate signal the controller of the VCR can detect perturbations of signal level which indicate that the cable box has changed channels. It is herein recognized that such an appropriate signal can be taken across the filter capacitor of a either sync or AGC portions of a video processor of the VCR.