Signal detector for a signal-seeking tuning system

Claim 1

In a television receiver having a signal-seeking tuning system for scanning the RF television frequency spectrum and automatically tuning said receiver to the frequency of a received RF television signal in response to a recognition signal, means for providing said recognition signal only in response to the reception of a proper RF television signal, comprising: a television tuner responsive to a received RF television signal for developing video and audio intermediate-frequency subcarrier signals; a first detector coupled to said tuner and including a circuit resonant at the frequency of said audio subcarrier signal for generating a first control effect; a second detector coupled to said tuner and including a circuit resonant at the frequency of said video subcarrier signal for generating a second control effect; means coupled to said tuner and responsive to said video subcarrier signal for deriving a horizontal synchronizing signal; a third detector coupled to said deriving means and responsive to said horizontal synchronizing signal for generating a third control effect; and coincidence gate means coupled to all three said detectors and responsive only to the presence of all three of said control effects for producing said recognition signal.