US3644831A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Modulation system
Assignee: General Electric Co
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Filing: 1967-10-09
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Granted: 1972-02-22
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Expires: 1987-10-09
Abstract
Abstract A narrow band transmitter utilizing a modulation technique in which a variable frequency oscillator is constrained to follow the frequency variations of a heavily limited single sideband signal to produce a constant-amplitude, narrow band output signal. The audio intelligence is applied to a single sideband modulator to produce a single sideband signal, which is then heavily limited to remove the amplitude information, with the intelligence being retained in the zero crossings of the limited signal. The limited S.S.B. signal controls a phase-locked oscillator loop, which varies the frequency of a variable frequency oscillator, forcing it to follow the frequency variation of the limited single sideband signal. The output from the phase-locked loop is a constant-amplitude, narrow band signal, the frequency excursion of which is substantially the same as the frequency excursion of the audio intelligence. The phase-locked loop may include frequency multiplication stages and Class-C amplifiers for processing the output signal from the oscillator to permit maximum efficiency in operation, since no amplitude information is being transmitted.
Inventors
- 👤 Alex Latker
- 👤 Johannes J Vandegraaf
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 11:23
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/68; H03; H03C; H03C3/00; H03C3/02; H03C3/09; H03C2200/00; H03C2200/0037; H03C2200/007
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
379 words
A narrow band constant-amplitude transmitter for transmitting audio information comprising: a. a single sideband generator having a first input, a second input and an output; audio means for communicating a first signal containing said audio information to said first input of said generator; means for communicating a second signal having a preselected frequency to said second input; said generator providing at the output thereof a single sideband signal representative of said first signal positioned on one side of said second signal; b. a limiter having an input and an output; means for communicating said single sideband signal to the input of said limiter; said limiter limiting said single sideband signal to generate at the output of said limiter a third signal having a substantially constant amplitude and having frequency variations corresponding to the frequency variations of said single sideband signal; c. a voltage controlled oscillator having an input and an output, said oscillator generating at the output thereof a fourth signal having a constant amplitude and a second preselected frequency; d. control means for modifying the frequency of said fourth signal, said control means including: 1. a phase detector having a first input, a second input and an output, means for communicating said third signal to the first input of said detector, means for communicating a sample of said fourth signal to the second input of said detector, network means for providing a communication path from the output of said detector to the input of said oscillator, said phase detector being responsive to instantaneous differences in phase between said third signal and said fourth signal to generate at the output of said detector a DC control signal whose magnitude is proportional to the difference in phase magnitude and whose polarity corresponds to the difference in phase direction between said third signal and said fourth signal, said control signal being applied to said oscillator to modify the frequency of said fourth signal to follow the frequency variations in said third signal; 2. said network means further operating to restrict said DC control signal such that variations in the frequency of said fourth signal are restricted to a range substantially equal to a selected audio band pass; e. output terminals, and output means communicating said fourth signal to said output terminals.
Claim 2
Dependent Claim
379 words
A narrow band constant-amplitude transmitter for transmitting audio information comprising: a. a single sideband generator having a first input, a second input and an output; audio means for communicating a first signal containing said audio information to said first input of said generator; means for communicating a second signal having a preselected frequency to said second input; said generator providing at the output thereof a single sideband signal representative of said first signal positioned on one side of said second signal; b. a limiter having an input and an output; means for communicating said single sideband signal to the input of said limiter; said limiter limiting said single sideband signal to generate at the output of said limiter a third signal having a substantially constant amplitude and having frequency variations corresponding to the frequency variations of said single sideband signal; c. a voltage controlled oscillator having an input and an output, said oscillator generating at the output thereof a fourth signal having a constant amplitude and a second preselected frequency; d. control means for modifying the frequency of said fourth signal, said control means including: 1. a phase detector having a first input, a second input and an output, means for communicating said third signal to the first input of said detector, means for communicating a sample of said fourth signal to the second input of said detector, network means for providing a communication path from the output of said detector to the input of said oscillator, said phase detector being responsive to instantaneous differences in phase between said third signal and said fourth signal to generate at the output of said detector a DC control signal whose magnitude is proportional to the difference in phase magnitude and whose polarity corresponds to the difference in phase direction between said third signal and said fourth signal, said control signal being applied to said oscillator to modify the frequency of said fourth signal to follow the frequency variations in said third signal; 2. said network means further operating to restrict said DC control signal such that variations in the frequency of said fourth signal are restricted to a range substantially equal to a selected audio band pass; e. output terminals, and output means communicating said fourth signal to said output terminals.
Claim 3
Dependent Claim
81 words
a balanced modulator having a first input, a second input and an output, means for communicating said reference signal to the first input of said modulator, means for communicating a sample of said fourth signal to the second input of said modulator, said modulator being responsive to said reference signal and said fourth signal to generate a fifth signal at the output of said modulator equal in frequency to the instantaneous frequency difference between said reference signal and said fourth signal;
Claim 4
Dependent Claim
81 words
a balanced modulator having a first input, a second input and an output, means for communicating said reference signal to the first input of said modulator, means for communicating a sample of said fourth signal to the second input of said modulator, said modulator being responsive to said reference signal and said fourth signal to generate a fifth signal at the output of said modulator equal in frequency to the instantaneous frequency difference between said reference signal and said fourth signal;
Claim 5
Dependent Claim
48 words
said network means further operating to restrict said DC control signal such that variations in the frequency of said fourth signal are restricted to a range substantially equal to a selected audio band pass; e. output terminals, and output means communicating said fourth signal to said output terminals.
Claim 6
Dependent Claim
48 words
said network means further operating to restrict said DC control signal such that variations in the frequency of said fourth signal are restricted to a range substantially equal to a selected audio band pass; e. output terminals, and output means communicating said fourth signal to said output terminals.
Claim 7
Dependent Claim
63 words
The transmitter of claim 1 including: means for applying a sample of said second signal to the input of said limiter, said sample of said second signal being of just great enough amplitude to cause said limiter to generate said third signal at the frequency of said second signal when said single sideband signal is not present at the input of said limiter.
Claim 8
Dependent Claim
185 words
A narrow band constant-amplitude transmitter for transmitting audio information comprising: a. a single sideband generator having a first input, a second input and an output; audio means for communicating a first signal containing said audio information to said first input of said generator; means for communicating a second signal having a preselected frequency to said second input; said generator providing at the output thereof a single sideband signal representative of said first signal positioned on one side of said second signal; b. a limiter having an input and an output; means for communicating said single sideband signal to the input of said limiter; said limiter limiting said single sideband signal to generate at the output of said limiter a third signal having a substantially constant amplitude and having frequency variations corresponding to the frequency variations of said single sideband signal; c. a voltage controlled oscillator having an input and an output, said oscillator generating at the output thereof a fourth Signal having a constant amplitude and a second preselected frequency; d. control means for modifying the frequency of said fourth signal, said control means including:
Claim 9
Dependent Claim
185 words
A narrow band constant-amplitude transmitter for transmitting audio information comprising: a. a single sideband generator having a first input, a second input and an output; audio means for communicating a first signal containing said audio information to said first input of said generator; means for communicating a second signal having a preselected frequency to said second input; said generator providing at the output thereof a single sideband signal representative of said first signal positioned on one side of said second signal; b. a limiter having an input and an output; means for communicating said single sideband signal to the input of said limiter; said limiter limiting said single sideband signal to generate at the output of said limiter a third signal having a substantially constant amplitude and having frequency variations corresponding to the frequency variations of said single sideband signal; c. a voltage controlled oscillator having an input and an output, said oscillator generating at the output thereof a fourth Signal having a constant amplitude and a second preselected frequency; d. control means for modifying the frequency of said fourth signal, said control means including:
Claim 10
Dependent Claim
141 words
a phase detector having a first input, a second input and an output, means for communicating said third signal to the first input of said detector, means for communicating said fifth signal to the second input of said detector, network means for providing a communication path from the output of said detector to the input of said oscillator, said phase detector being responsive to instantaneous differences in phase between said third signal and said fifth signal to generate at the output of said detector a DC control signal whose magnitude is proportional to the difference in phase magnitude and whose polarity corresponds to the difference in phase direction between said third signal and said fifth signal, said control signal being applied to said oscillator to modify the frequency of said fourth signal to follow the frequency variations in said third signal;
Claim 11
Dependent Claim
141 words
a phase detector having a first input, a second input and an output, means for communicating said third signal to the first input of said detector, means for communicating said fifth signal to the second input of said detector, network means for providing a communication path from the output of said detector to the input of said oscillator, said phase detector being responsive to instantaneous differences in phase between said third signal and said fifth signal to generate at the output of said detector a DC control signal whose magnitude is proportional to the difference in phase magnitude and whose polarity corresponds to the difference in phase direction between said third signal and said fifth signal, said control signal being applied to said oscillator to modify the frequency of said fourth signal to follow the frequency variations in said third signal;
Claim 12
Dependent Claim
48 words
said network means further operating to restrict said DC control signal such that variations in the frequency of said fourth signal are restricted to a range substantially equal to a selected audio band pass; e. output terminals, and output means communicating said fourth signal to said output terminals.
Claim 13
Dependent Claim
48 words
said network means further operating to restrict said DC control signal such that variations in the frequency of said fourth signal are restricted to a range substantially equal to a selected audio band pass; e. output terminals, and output means communicating said fourth signal to said output terminals.
Claim 14
Dependent Claim
63 words
The transmitter of claim 3 including: means for applying a sample of said second signal to the input of said limiter, said sample of said second signal being of just great enough amplitude to cause said limiter to generate said third signal at the frequency of said second signal when said single sideband signal is not present at the input of said limiter.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-02-21 | 1975-08-23 | 1976-02-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-02-21 | 1979-08-23 | 1980-02-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-02-21 | 1983-08-23 | 1984-02-22 | $7700.00 | Window Closed / Lapsed |