Electricity: measuring and testing – Measuring – testing – or sensing electricity – per se – Frequency of cyclic current or voltage
Patent
1976-07-29
1978-04-11
Heyman, John S.
Electricity: measuring and testing
Measuring, testing, or sensing electricity, per se
Frequency of cyclic current or voltage
328129, 324 83D, H03D 1300
Patent
active
040841278
ABSTRACT:
In a phase locked loop type of tuning system for a television receiver having provisions for tuning the receiver to non-standard frequency carriers having frequencies arbitrarily near respective frequencies of the standard broadcast carriers, a digital frequency deviation detector is provided to determine whether the frequency of at least one variable frequency signal developed by the tuning system is within a predetermined range of its nominal value. The frequency deviation detector includes a D type flip-flop to generate a signal whose frequency is equal to the difference between the frequency of the variable frequency signal and a fixed frequency signal. A counter is enabled during a predetermined portion of at least one cycle of the difference signal to count period (cycles) of the fixed frequency signal. The accumulation of at least a predetermined count indicates that the variable frequency signal is within a predetermined frequency difference with respect to the frequency of the fixed frequency signal. The frequency of the fixed frequency signal is substantially proportional to the nominal frequency of the variable frequency signal. Because the frequency deviation detector does not require components (e.g., capacitors) conventionally employed with analog type of frequency deviation detectors, it may be readily incorporated in a digital integrated circuit with, for example, other portions of a digital tuning system.
REFERENCES:
patent: 3579104 (1971-05-01), Pignard et al.
patent: 3579126 (1971-05-01), Paul
patent: 3585508 (1971-06-01), Crowther
patent: 3671876 (1972-06-01), Oshiro
patent: 3683345 (1972-08-01), Faulkes et al.
patent: 3755746 (1973-08-01), Hogue et al.
patent: 3764903 (1973-10-01), Griswold
Emanuel Peter M.
Heyman John S.
RCA Corporation
Schaefer Kenneth R.
Whitacre Eugene M.
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