Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1976-11-18
1978-03-14
Griffin, Robert L.
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
325420, 325464, 334 16, H04B 116
Patent
active
040794202
ABSTRACT:
In a channel selecting apparatus for a television receiver having an electronic tuning tuner for changing the receiving frequency in accordance with an analog control signal applied thereto; a memory has a plurality of addresses for storing respective digital codes each identifying a respective channel and which are selectively activated so as to effect read out of the respective channel identifying digital code to a digital-to-analog converter which converts the same into a respective analog control signal for the tuner. A deviation of the receiving frequency, as established in response to the analog control signal, from the correct receiving frequency for the channel identified by the digital code then being read out of the memory is detected, and, in response to a detected deviation within a pull-in range of an automatic fine tuning (AFT) circuit, the latter changes the digital code applied to the converter in the sense for removing such deviation and thereby achieving the correct tuned condition. Further, when the detected deviation is outside the pull-in range of the AFT circuit, sweeping changes are made in the digital code applied to the converter for cyclically varying the receiving frequency and thereby bringing the latter at least into the pull-in range of the AFT circuit. The modified digital code resulting from the operation of the AFT circuit and/or from the sweeping changes in such code is stored in the memory in place of the read out digital code resulting in such deviation.
REFERENCES:
patent: 3715687 (1973-02-01), Solender
patent: 3968440 (1976-07-01), Ehni
Mogi Takao
Okada Hisao
Bookbinder Marc E.
Griffin Robert L.
Sinderbrand Alvin
Sony Corporation
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