US3883806A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Demodulator circuit for phase modulated communication signals
Assignee: Boeing North American Inc
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Filing: 1974-03-07
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Granted: 1975-05-13
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Expires: 1994-03-07
Abstract
Abstract A demodulator circuit provides a local reference signal which is continuous irrespective of phase modulation in the communication signal to be demodulated by reversing the phase of the output of a phase locked loop voltage controlled oscillator each time the communication signal reverses phase prior to comparing the two in a phase detector.
Inventors
- 👤 Vincent R Delong
- 👤 Robert L Craiglow
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 05:11
CPC Classifications
H; H03; H03D; H03D3/00; H03D3/02; H03D3/24; H03D3/241
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
181 words
A demodulator circuit for providing a local reference signal for coherently demodulating communication signals containing phase modulation in the form of phase reversals in the carrier signal, comprising: a voltage controlled oscillator for phase locked loop operation; phase shifting circuit means for providing a reference signal which is out of phase with the output of said voltage controlled oscillator by the same amount and in a direction opposite to the phase shift produced by phase locked loop operation; first detector circuit means for providing a bilevel phase reversing signal which constitutes the demodulated output whose level is dependent on the phase difference between the communication and reference signals; phase reversing circuit means for providing a signal at its output which is 0* or 180* out-of-phase with the output of said voltage controlled oscillator, the phase shift being dependent on the level of said phase reversing signal; and second detector circuit means for applying to said voltage controlled oscillator a controL signal which is indicative of the phase difference between the communication signal and the output of said phase reversing circuit means.
Claim 2
Dependent Claim
181 words
A demodulator circuit for providing a local reference signal for coherently demodulating communication signals containing phase modulation in the form of phase reversals in the carrier signal, comprising: a voltage controlled oscillator for phase locked loop operation; phase shifting circuit means for providing a reference signal which is out of phase with the output of said voltage controlled oscillator by the same amount and in a direction opposite to the phase shift produced by phase locked loop operation; first detector circuit means for providing a bilevel phase reversing signal which constitutes the demodulated output whose level is dependent on the phase difference between the communication and reference signals; phase reversing circuit means for providing a signal at its output which is 0* or 180* out-of-phase with the output of said voltage controlled oscillator, the phase shift being dependent on the level of said phase reversing signal; and second detector circuit means for applying to said voltage controlled oscillator a controL signal which is indicative of the phase difference between the communication signal and the output of said phase reversing circuit means.
Claim 3
Dependent Claim
43 words
The demodulator circuit of claim 1 wherein said first circuit means includes a phase detector for receiving the communication and reference signals and a low pass filter and limiter circuit connected in series between the detector output and said phase reversing circuit means.
Claim 4
Dependent Claim
177 words
A demodulator circuit for providing a local reference signal for coherently demodulating a communication signal containing phase modulation in the form of phase reversals in the carrier signal comprising: a voltage controlled oscillator for phase locked loop operation; first detector circuit means for providing a bilevel phase reversing signal which constitutes the demodulated output whose level is dependent on the phase difference between the communication signal and the output of said voltage controlled oscillator; phase reversing circuit means for shifting a signal by 0* or 180*, the shift being dependent on the level of said phase reversing signal; second detector circuit means for applying to said voltage controlled oscillator a control signal indicative of the phase difference between the communication signal and another signal applied to a second input thereof; and circuit means for applying the output of said voltage controlled oscillator to the second input of said second detector circuit means via said phase reversing circuit including means for shifting the phase of the signal passing therethrough by the amount required for phase locked loop operation.
Claim 5
Dependent Claim
177 words
A demodulator circuit for providing a local reference signal for coherently demodulating a communication signal containing phase modulation in the form of phase reversals in the carrier signal comprising: a voltage controlled oscillator for phase locked loop operation; first detector circuit means for providing a bilevel phase reversing signal which constitutes the demodulated output whose level is dependent on the phase difference between the communication signal and the output of said voltage controlled oscillator; phase reversing circuit means for shifting a signal by 0* or 180*, the shift being dependent on the level of said phase reversing signal; second detector circuit means for applying to said voltage controlled oscillator a control signal indicative of the phase difference between the communication signal and another signal applied to a second input thereof; and circuit means for applying the output of said voltage controlled oscillator to the second input of said second detector circuit means via said phase reversing circuit including means for shifting the phase of the signal passing therethrough by the amount required for phase locked loop operation.
Claim 6
Dependent Claim
30 words
The demodulator circuit of claim 3 wherein said first detector circuit means includes a phase detector, a low pass filter and a limiter circuit connected in series with each other.
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) | 1978-05-12 | 1978-11-11 | 1979-05-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-12 | 1982-11-11 | 1983-05-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-12 | 1986-11-11 | 1987-05-13 | $7700.00 | Window Closed / Lapsed |