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US3755734A
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US
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Frequency deviation monitor and measuring device
Assignee: PepsiAmericas Inc
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Filing: 1972-07-24
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Granted: 1973-08-28
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Expires: 1992-07-24
Abstract
Abstract A frequency deviation monitor for measuring instantaneous variations of an input signal from a reference frequency, including an input circuit developing an intermediate signal of constant amplitude, a phase-shifting circuit that shifts the signal in phase by an amount and in a direction representative of deviations of the signal from a given reference frequency, and a key signal generator that develops short-duration key signal pulses at the input signal frequency. The signals from the phaseshifting circuit and the key signal generator are applied to a sampling demodulator that develops an output signal having an amplitude and polarity indicative of the deviation of the input signal fro m the reference frequency.
Inventors
- 👤 C Blanyer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 18:29
CPC Classifications
G; G01; G01R; G01R23/00
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
193 words
A frequency deviation monitor for measuring the instantaneous deviation of an input signal from a reference frequency, comprising: an input circuit for developing an intermediate signal having a frequency corresponding to the frequency of an input signal applied thereto and having a constant amplitude; phase-shifting means, coupled to the input circuit, for generating a phase-shift signal having a frequency corresponding to the frequency of the intermediate signal but shifted in phase by an amount and in a direction indicative of any deviation of the intermediate signal, and hence the input signal, from a given reference frequency; key signal generator means, coupled to the input circuit, for generating a key signal comprising a series of key pulses each having a duration much shorter than a half-cycle of the intermediate signal and recurring at an integral multiple of the intermediate signal frequency; and a sampling demodulator, coupled to the phase-shifting means and to the key signal generator means, for sampling the phaseshift signal at time intervals determined by the key signal pulses to develop an output signal having an amplitude and polarity representative of the instantaneous deviation of the input signal from the reference frequency.
Claim 2
Dependent Claim
193 words
A frequency deviation monitor for measuring the instantaneous deviation of an input signal from a reference frequency, comprising: an input circuit for developing an intermediate signal having a frequency corresponding to the frequency of an input signal applied thereto and having a constant amplitude; phase-shifting means, coupled to the input circuit, for generating a phase-shift signal having a frequency corresponding to the frequency of the intermediate signal but shifted in phase by an amount and in a direction indicative of any deviation of the intermediate signal, and hence the input signal, from a given reference frequency; key signal generator means, coupled to the input circuit, for generating a key signal comprising a series of key pulses each having a duration much shorter than a half-cycle of the intermediate signal and recurring at an integral multiple of the intermediate signal frequency; and a sampling demodulator, coupled to the phase-shifting means and to the key signal generator means, for sampling the phaseshift signal at time intervals determined by the key signal pulses to develop an output signal having an amplitude and polarity representative of the instantaneous deviation of the input signal from the reference frequency.
Claim 3
Dependent Claim
39 words
A frequency deviation monitor, according to claim 1, in which the phase-shifting means comprises an active peaking network including an amplifier having a negative feedback circuit which comprises a tunable bridged-T notch filter, tuned to the given reference frequency.
Claim 4
Dependent Claim
34 words
A frequency deviation monitor, according to claim 2, in which the phase-shifting means further comprises an inverter coupled to the output of the amplifier, producing two phase-shift signals displaced 180* relative to each other.
Claim 5
Dependent Claim
71 words
A frequency deviation monitor, according to claim 1, in which the phase-shifting means generates two phase-shift signals corresponding in frequency and amplitude but displaced 180* relative to each other, and in which the key signal generator means generates two key signals displaced 180* relative to each other, the sampling demodulator utilizing each key signal to sample one phase-shift signal and thus afford a sampling rate of twice the input signal frequency.
Claim 6
Dependent Claim
47 words
A frequency deviation monitor, according to claim 4, in which the key signal generator means comprises an integrator coupled to a push-pull differentiator, developing key signal pulses that coincide with zero crossings of the phase-shift signals whenever the input signal frequency corresponds to the given reference frequency.
Claim 7
Dependent Claim
60 words
A frequency deviation monitor according to claim 4 in which the sampling demodulator comprises a storage capacitor, and two semiconductor gates each having a main conduction path connected to the storage capacitor for applying the instantaneous phase-shift signals to the storage capacitor, the semiconductor gates each having a gate electrode to which one of the two keying signals is applied.
Claim 8
Dependent Claim
60 words
A frequency deviation monitor, according to claim 1, and further comprising output circuit means, coupled to the demodulator, correcting the output signal for non-linearity in the phase-shift signal amplitudes, relative to frequency variations, to afford a corrected output signal that varies approximately linearly with phase over a range of frequencies up to 10 percent above and below the reference frequency.
Claim 9
Dependent Claim
38 words
A frequency deviation monitor, according to claim 7, and further comprising an indicating instrumenT, coupled to the output circuit means, actuated by the corrected output signal to afford an instantaneous indication of the frequency of the input signal.
Claim 10
Dependent Claim
52 words
A frequency deviation monitor, according to claim 8, and further comprising peak holder means, interposed between the output circuit means and the indicating instrument, for storing the maximum amplitude of the corrected output signal for a substantial period of time to allow effective determination of maximum frequency changes in the input signal.
References Cited (Backward Citations)
US2480128A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-08-27 | 1977-02-26 | 1977-08-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-27 | 1981-02-26 | 1981-08-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-27 | 1985-02-26 | 1985-08-28 | $7700.00 | Window Closed / Lapsed |