WIDE BAND AFT CIRCUIT FOR TELEVISION RECEIVERS

ABSTRACT OF THE DISCLOSURE A wide-band automatic fine tuning (AFT) circuit capable of a ?2 MHz pull-in range without false lockups responds to the output of a picture carrier discriminator, a sound carrier discriminator and a vertical synchronizing signal sensing means to operate a reversible digita...

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Bibliographische Detailangaben
Hauptverfasser:	RZESZEWSKI, THEODORE S, SIDERIS, SOTIRIOS
Format:	Patent
Sprache:	eng ; fre
Schlagworte:	BASIC ELECTRONIC CIRCUITRY ELECTRIC COMMUNICATION TECHNIQUE ELECTRICITY PICTORIAL COMMUNICATION, e.g. TELEVISION SELECTING RESONANT CIRCUITS TUNING RESONANT CIRCUITS
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Beschreibung
Zusammenfassung:	ABSTRACT OF THE DISCLOSURE A wide-band automatic fine tuning (AFT) circuit capable of a ?2 MHz pull-in range without false lockups responds to the output of a picture carrier discriminator, a sound carrier discriminator and a vertical synchronizing signal sensing means to operate a reversible digital counter in either its count up or count down direction depending upon the relationship of the outputs of the two discrimina-tors and the synchronizing signal sensing circuit. The output of the counter is supplied to a digital-to-analog converter which produces a tuning control voltage used for controlling the frequency of operation of the local oscil-lator of the receiver. The output of the digital-to-analog converter is added to a conventional AFT voltage which main-tains the desired tuning once it has been established by the wide-band AFT system.