US3691467A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Demodulating apparatus
Assignee: A C COSSER Ltd
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Filing: 1970-04-22
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Granted: 1972-09-12
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Expires: 1990-04-22
Abstract
Abstract Demodulating apparatus for indicating the difference in depth of modulating of a carrier oscillation by two modulating signals of different frequencies f1 and f2 comprising an aerial with a detector which provides an input to two switching modulators. A first variable-frequency oscillator providing a first reference signal of substantially the same frequency and phase as the signal of frequency f1 is connected to an input of one of the modulators. A second variable-frequency oscillator providing a second reference signal of substantially the same frequency and phase as the signal of frequency f2 is connected to an input of the other modulators. The outputs of the modulators are connected through low-pass filters to a differential amplifier with an associated meter for indicating the difference in the magnitudes of the d.c. components of the outputs of the two modulators.
Inventors
- 👤 Michael Patrick Mansfield
- 👤 Howard John Prangnell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 17:36
CPC Classifications
G; G01; G01S; G01S1/00; G01S1/02
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
138 words
An apparatus for indicating the difference in depths of modulation of an input carrier oscillation signal by two modulating signals of different frequencies f1 and f2 comprising: two multipliers; said input signal connected to the two multipliers; means for providing to one of the multipliers a first reference signal of the same frequency and phase as the signal of frequency f1, said one multiplier producing an output having a d.c. component; means for Providing to the other multiplier a second reference signal of the same frequency and phase as the signal of frequency f2, the first and second reference signals being of the same amplitude, said other multiplier producing an output having a d.c. component; and means for providing an indication of the difference in the magnitudes of the d.c. components of the outputs of the two multipliers.
Claim 2
Independent Claim
138 words
An apparatus for indicating the difference in depths of modulation of an input carrier oscillation signal by two modulating signals of different frequencies f1 and f2 comprising: two multipliers; said input signal connected to the two multipliers; means for providing to one of the multipliers a first reference signal of the same frequency and phase as the signal of frequency f1, said one multiplier producing an output having a d.c. component; means for Providing to the other multiplier a second reference signal of the same frequency and phase as the signal of frequency f2, the first and second reference signals being of the same amplitude, said other multiplier producing an output having a d.c. component; and means for providing an indication of the difference in the magnitudes of the d.c. components of the outputs of the two multipliers.
Claim 3
Dependent Claim
130 words
An apparatus as claimed in claim 1 wherein each of said means for providing a reference signal comprises: a variable frequency oscillator having a frequency-and-phase control and two outputs providing signals in quadrature with one another; a first of said output being connected to one of said multipliers; a subsidiary multiplier connected to the said input, the second output being connected to the subsidiary multiplier; and a low-pass filter, an output of said subsidiary multiplier being connected to the frequency and phase control of the oscillator through the low-pass filter; whereby the output of said low-pass filter controls the phase and frequency of said variable frequency oscillator so as to maintain the output from said oscillator at the same frequency and phase as the corresponding modulating signal of said input.
Claim 4
Dependent Claim
52 words
An apparatus as claimed in claim 2 wherein the oscillator is arranged to vibrate at a multiple of the frequency of the reference signal, and in which the means for providing a reference signal further include a phase shifter which digitally divides the oscillation to provide the two output signals in quadrature.
Claim 5
Dependent Claim
16 words
An apparatus as claimed in claim 1 wherein the input comprises an aerial and a detector.
Claim 6
Dependent Claim
13 words
An apparatus as claimed in claim 1 wherein the multipliers are switching modulators.
Claim 7
Dependent Claim
71 words
An apparatus as claimed in claim 1 wherein the means for providing an indication comprise two low-pass filters and a difference amplifier with an associated meter, the two multipliers being connected to the difference amplifier through the two low-pass filters; whereby said two low-pass filters derive said d.c. components from the outputs of said two multipliers and said difference amplifier provides an indication of the difference between said two d.c. components.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-09-12 | 1976-03-13 | 1976-09-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-09-12 | 1980-03-13 | 1980-09-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-09-12 | 1984-03-13 | 1984-09-12 | $7700.00 | Window Closed / Lapsed |