US3879670A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Synchronous demodulator circuit
Assignee: Westinghouse Electric Corp
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Filing: 1974-04-11
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Granted: 1975-04-22
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Expires: 1994-04-11
Abstract
Abstract A synchronous demodulator is provided for receiving signals including one that is subject to variation in waveform and a predetermined reference signal having a known waveform from which signals is produced a demodulated output representing the relationship between the first and second signals with respect to their phase and amplitude. The apparatus includes means such as a signal transformer with a center-tapped secondary to produce two phase displaced signals from the first signal which are then applied by means such as a gate controlled two-channel input amplifier to the input of an amplifier such as an operational amplifier from which the demodulated output is obtained. Application to reactive load division between parallel AC generators is advantageous.
Inventors
- 👤 David A Fox
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 07:34
CPC Classifications
H; H02; H02J; H02J3/00; H02J3/04; H02J3/08; H03; H03D; H03D3/00; H03D3/02; H03D3/18
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
124 words
A synchronous demodulator comprising: a first terminal for receiving a first time varying electrical signal whose waveform is subject to variation, a second terminal for receiving a Second, reference, time varying electrical signal having a predetermined waveform not subject to variation; means for developing two phase displaced signals having 0* and 180* phase displacement respectively from said first signal and equal peak magnitude with respect to a common point; means for amplifying; and means for applying switched signals comprising said phase displaced signals in synchronism with said reference signal to an input terminal of said means for amplifying; said means for amplifying having an output terminal at which appears a demodulated output representing the relationship between said phase displaced signals and said reference signal.
Claim 2
Dependent Claim
124 words
A synchronous demodulator comprising: a first terminal for receiving a first time varying electrical signal whose waveform is subject to variation, a second terminal for receiving a Second, reference, time varying electrical signal having a predetermined waveform not subject to variation; means for developing two phase displaced signals having 0* and 180* phase displacement respectively from said first signal and equal peak magnitude with respect to a common point; means for amplifying; and means for applying switched signals comprising said phase displaced signals in synchronism with said reference signal to an input terminal of said means for amplifying; said means for amplifying having an output terminal at which appears a demodulated output representing the relationship between said phase displaced signals and said reference signal.
Claim 3
Dependent Claim
124 words
A synchronous demodulator comprising: a first terminal for receiving a first time varying electrical signal whose waveform is subject to variation, a second terminal for receiving a Second, reference, time varying electrical signal having a predetermined waveform not subject to variation; means for developing two phase displaced signals having 0* and 180* phase displacement respectively from said first signal and equal peak magnitude with respect to a common point; means for amplifying; and means for applying switched signals comprising said phase displaced signals in synchronism with said reference signal to an input terminal of said means for amplifying; said means for amplifying having an output terminal at which appears a demodulated output representing the relationship between said phase displaced signals and said reference signal.
Claim 4
Dependent Claim
124 words
A synchronous demodulator comprising: a first terminal for receiving a first time varying electrical signal whose waveform is subject to variation, a second terminal for receiving a Second, reference, time varying electrical signal having a predetermined waveform not subject to variation; means for developing two phase displaced signals having 0* and 180* phase displacement respectively from said first signal and equal peak magnitude with respect to a common point; means for amplifying; and means for applying switched signals comprising said phase displaced signals in synchronism with said reference signal to an input terminal of said means for amplifying; said means for amplifying having an output terminal at which appears a demodulated output representing the relationship between said phase displaced signals and said reference signal.
Claim 5
Dependent Claim
23 words
The subject matter of claim 1 wherein: said means for developing two phase displaced signals comprises a signal transformer with a center-tapped secondary.
Claim 6
Dependent Claim
54 words
The subject matter of claim 1 wherein: said means for amplifying comprises an inverting input terminal and a non-inverting input terminal; said means for applying switched signals is connected to said inverting input terminal and said non-inverting input terminal is maintained at a reference level; and said output terminal is at said common point.
Claim 7
Dependent Claim
60 words
The subject matter of claim 1 wherein: said means for amplifying comprises an inverting input terminal and a non-inverting input terminal; said means for applying switched signals is connected to said inverting input terminal and said non-inverting input terminal is maintained at a reference level; and said output terminal is resistively coupled to said means for developing phase displaced signals.
Claim 8
Dependent Claim
45 words
The subject matter of claim 1 wherein: said means for amplifying comprises an inverting input terminal and a non-inverting input terminal; said means for applying switched signals is connected to said non-inverting input terminal and said inverting input terminal is connected to said output terminal.
References Cited (Backward Citations)
US3659210A
Cited
US3699461A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-04-21 | 1978-10-21 | 1979-04-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-21 | 1982-10-21 | 1983-04-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-21 | 1986-10-21 | 1987-04-22 | $7700.00 | Window Closed / Lapsed |