Marker signal detecting systems.

摘要

A system for detecting a marker signal (SM) with a predetermined pattern inserted periodically in an information signal (SA) comprises a circuit (5) which repetitively generates window signals (Sw) and successively shifts the window signals (Sw) in a step-wise fashion during a predetermined interval, a detecting circuit (16) which employs the window signals (Sw) to detect at least a portion of a marker signal (SM) in the information signal (SA) when at least the portion of the detected marker signal (SM) ocurs during one of the window signals (Sw), a circuit (17) which determines when the detected marker signal (SM) has the predetermined pattern to generate a net marker signal (SM') in response thereto, and a circuit (32) responsive to the net marker signal (SM') which repetitively generates subsequent unshifted window signals (Sw) beginning a predetermined time after the detected marker signal (SM).