Frequency synthesizer tuning system with signal seek control

Details Frequency synthesizer tuning system with signal seek control Frequency synthesizer tuning system with signal seek control

1976-07-22

1977-08-09

Griffin, Robert L.

Facsimile and static presentation processing

Facsimile

Specific signal processing circuitry

325421, 325464, H04N 544

Patent

active

040415350

ABSTRACT:
A television tuning system employs a frequency synthesizer system for establishing the tuning of the receiver. A first programmable frequency divider controlled by a reversible counter is connected between the output of a reference oscillator and a phase comparator to which the output of the local oscillator, after passing through another programmable frequency divider, also is applied. The phase comparator output is a tuning voltage used to control the tuning of the local oscillator. A logic circuit is coupled to sense predetermined relationships of signals from a picture carrier detector, a sound carrier detector, an AFT discriminator circuit, and the presence of vertical synchronization signal components for changing the count in the reversible binary counter to adjust the first programmable frequency divider to compensate for channel frequency offsets which may occur in excess of the pull-in range of the AFT discriminator circuit. To permit operation of the receiver as a signal seek receiver, a pair of signal seek pushbuttons for the "up" and for the "down" direction, respectively, are provided. Operation of either of these pushbuttons functions in conjunction with further logic circuitry and in conjunction with timing circuitry to automatically step tune the receiver channel-by-channel in the selected direction until a channel with a signal present is sensed by the first logic circuit, whereupon the signal seek circuit operation is disabled until one or the other of the signal seek pushbuttons is reactivated.

REFERENCES:
patent: 3949158 (1976-04-01), Rzeszewski et al.
patent: 3973228 (1976-08-01), Mueller et al.
patent: 3980951 (1976-09-01), Breeze et al.
IEEE transaction on Concumer Electronics on "Simplified TV Tuning System" by Hilliker, pp. 61-68, 2-1976.

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