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US3714567A
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Detector-demodulator for modulated (reversed) ac and dc signals
Assignee: Canadian Patents and Development Ltd
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Filing: 1971-05-12
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Granted: 1973-01-30
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Expires: 1991-05-12
Abstract
Abstract A detector-demodulator for current and voltage measuring devices having a modulated (reversing) output wherein the detectordemodulator incorporates time constant elements after the demodulation stage that permit the use of a fast acting detector and yet achieves a narrow bandwidth performance. The apparatus comprises first and second switches connected in parallel to the output of the measuring device, voltage storage means incorporating long time constant elements connected to each of the outputs of said switches, switch operating means for opening and closing said switches in a predetermined timing sequence, and means attached to the output of the voltage storage means for measuring the difference in the voltage levels stored in the voltage storage means. The timing sequence may be controlled manually or automatically and would be arranged such that the modulated output would be sampled only during a relatively steady-state period so that switching transients would not appear in the output.
Inventors
- 👤 N Kusters
- 👤 Martin M Mac
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 03:24
CPC Classifications
G; G01; G01R; G01R19/00; G01R19/18; G01R19/0046; G01R19/0053; G01R19/10
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
134 words
A detector-demodulator for current, impedance, and voltage measuring devices of the type having a periodically reversed (modulated) output comprising: a. a null sensing device with a short time constant characteristic allowing rapid reversal, b. first and second signal channels each channel including signal storage means having a long time constant characteristic in relation to that of the said null sensing device, c. means for alternately applying the output of the said null sensing device to the first and second channels in a predetermined timing sequence related to the reversal timing of the measuring device, and d. means connected to the output of the first and second signal channels for measuring the relationship of the signal levels stored in the signal storage means and providing an output relaTed to the relationship of these voltage levels.
Claim 2
Dependent Claim
134 words
A detector-demodulator for current, impedance, and voltage measuring devices of the type having a periodically reversed (modulated) output comprising: a. a null sensing device with a short time constant characteristic allowing rapid reversal, b. first and second signal channels each channel including signal storage means having a long time constant characteristic in relation to that of the said null sensing device, c. means for alternately applying the output of the said null sensing device to the first and second channels in a predetermined timing sequence related to the reversal timing of the measuring device, and d. means connected to the output of the first and second signal channels for measuring the relationship of the signal levels stored in the signal storage means and providing an output relaTed to the relationship of these voltage levels.
Claim 3
Dependent Claim
134 words
A detector-demodulator for current, impedance, and voltage measuring devices of the type having a periodically reversed (modulated) output comprising: a. a null sensing device with a short time constant characteristic allowing rapid reversal, b. first and second signal channels each channel including signal storage means having a long time constant characteristic in relation to that of the said null sensing device, c. means for alternately applying the output of the said null sensing device to the first and second channels in a predetermined timing sequence related to the reversal timing of the measuring device, and d. means connected to the output of the first and second signal channels for measuring the relationship of the signal levels stored in the signal storage means and providing an output relaTed to the relationship of these voltage levels.
Claim 4
Dependent Claim
134 words
A detector-demodulator for current, impedance, and voltage measuring devices of the type having a periodically reversed (modulated) output comprising: a. a null sensing device with a short time constant characteristic allowing rapid reversal, b. first and second signal channels each channel including signal storage means having a long time constant characteristic in relation to that of the said null sensing device, c. means for alternately applying the output of the said null sensing device to the first and second channels in a predetermined timing sequence related to the reversal timing of the measuring device, and d. means connected to the output of the first and second signal channels for measuring the relationship of the signal levels stored in the signal storage means and providing an output relaTed to the relationship of these voltage levels.
Claim 5
Dependent Claim
21 words
A detector-demodulator as in claim 1 wherein the signal stored is a voltage and the storage means is an R-C circuit.
Claim 6
Dependent Claim
136 words
A detector-demodulator for current, voltage, and impedance measuring devices of the type having a modulated output that is reversed periodically comprising: a. a null sensing device with a short time constant characteristic allowing rapid reversal, b. first and second switches connected in parallel to the output of the said null sensing device, c. voltage storage means connected to each of the outputs of said switches, said means having a long time constant characteristic in relation to that of the said null sensing device, d. switch operating means for opening and closing said switches in a predetermined timing sequence, and e. means attached to the output of the voltage storing means for measuring the difference in the voltage levels stored in the voltage storage means and providing an output related to the difference of these voltage levels.
Claim 7
Dependent Claim
136 words
A detector-demodulator for current, voltage, and impedance measuring devices of the type having a modulated output that is reversed periodically comprising: a. a null sensing device with a short time constant characteristic allowing rapid reversal, b. first and second switches connected in parallel to the output of the said null sensing device, c. voltage storage means connected to each of the outputs of said switches, said means having a long time constant characteristic in relation to that of the said null sensing device, d. switch operating means for opening and closing said switches in a predetermined timing sequence, and e. means attached to the output of the voltage storing means for measuring the difference in the voltage levels stored in the voltage storage means and providing an output related to the difference of these voltage levels.
Claim 8
Dependent Claim
20 words
A detector-demodulator as in claim 3 wherein the switch operating means is synchronized with the reversal of the measuring device.
Claim 9
Dependent Claim
20 words
A detector-demodulator as in claim 3 in which the voltage storage means comprises a resistor, a capacitor and an amplifier.
Claim 10
Dependent Claim
16 words
A detector-demodulator as in claim 3 in which the difference measuring means is a difference amplifier.
Claim 11
Dependent Claim
271 words
A detector-demodulator for current and voltage measuring devices of the type using modulated AC signals that are reversed in phase periodically and a null sensing device having a short time constant characteristic allowing rapid reversal comprising: a. a phase sensitive detector connected to the output of the measuring device and providing two outputs, one an in-phase DC signal and the other a quadrature DC signal, b. first and second signal channels each channel including signal storage means having a long time constant characteristic in relation to that of the null sensing device, c. means for alternately applying the in-phase output of the phase sensitive detector to the first and second channels in a predetermined timing sequence related to the reversal timing of the measuring device, d. means connected to the output of the first and second signal channels for measuring the relationship of the signal levels stored in the signal storage means and providing an output related to the relationship of these voltage levels, e. third and fourth signal channels each channel including signal storage means having a long time constant characteristic in relation to that of the null sensing device, f. means for alternately applying the quadrature output of the phase sensitive detector to the third and fourth signal channels in a predetermined timing sequence related to the reversal timing of the measuring device, and g. means connected to the output of the third and fourth signal channels for measuring the relationship of the signal levels stored in the signal storage means in the third and fourth channels an providing an output related to the relationship of these voltage levels.
Claim 12
Dependent Claim
271 words
A detector-demodulator for current and voltage measuring devices of the type using modulated AC signals that are reversed in phase periodically and a null sensing device having a short time constant characteristic allowing rapid reversal comprising: a. a phase sensitive detector connected to the output of the measuring device and providing two outputs, one an in-phase DC signal and the other a quadrature DC signal, b. first and second signal channels each channel including signal storage means having a long time constant characteristic in relation to that of the null sensing device, c. means for alternately applying the in-phase output of the phase sensitive detector to the first and second channels in a predetermined timing sequence related to the reversal timing of the measuring device, d. means connected to the output of the first and second signal channels for measuring the relationship of the signal levels stored in the signal storage means and providing an output related to the relationship of these voltage levels, e. third and fourth signal channels each channel including signal storage means having a long time constant characteristic in relation to that of the null sensing device, f. means for alternately applying the quadrature output of the phase sensitive detector to the third and fourth signal channels in a predetermined timing sequence related to the reversal timing of the measuring device, and g. means connected to the output of the third and fourth signal channels for measuring the relationship of the signal levels stored in the signal storage means in the third and fourth channels an providing an output related to the relationship of these voltage levels.
References Cited (Backward Citations)
US3441851A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-01-30 | 1976-07-31 | 1977-01-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-30 | 1980-07-31 | 1981-01-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-30 | 1984-07-31 | 1985-01-30 | $7700.00 | Window Closed / Lapsed |