System for detecting a marker signal inserted in an information signal

摘要

A system for detecting a marker signal with a predetermined pattern inserted periodically in an information signal comprises a circuit which repetitively generates window signals and successively shifts the window signals in a step-wise fashion during a predetermined interval, a detecting circuit which employs the window signals to detect at least a portion of a marker signal in the information signal when at least the portion of the detected marker signal occurs during one of the window signals, a circuit which determines when the detected marker signal has the predetermined pattern to generate a net marker signal in response thereto, and a circuit responsive to the net marker signal which repetitively generates subsequent unshifted window signals beginning a predetermined time after the detected marker signal.