Television signal determination in an automatic tuning system

摘要

A television signal determination circuit is associated with an automatic tuning system, which automatically tunes a television set to local channels, in order to determine whether received signals are desired television signals. The television signal determination circuit comprises a first counter means for counting received synchronizing signals for a predetermined period of time, a second counter means for counting reference clock signals for the predetermined period of time, and a determination means for determining whether the synchronizing signals are received by a predetermined number within the predetermined period of time by comparing output signals from the first and second counter means.