US4053834A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Narrowband phase modulation communication system which eliminates thresholding
Assignee: Textron Inc
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Filing: 1975-09-12
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Granted: 1977-10-11
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Expires: 1995-09-12
Abstract
Abstract A narrowband phase modulation communication system is disclosed which eliminates thresholding. At the transmitter, quadrature modulation which produces very large maximum phase deviation is employed in conjunction with a constant amplitude limiter. The constant amplitude resultant contains the carrier and voice signal components in quadrature and is transmitted, at a suitable frequency, in this form. At the receiver, a narrowband phase locked loop is employed for demodulation. This demodulating loop coherently tracks the carrier component and eliminates the thresholding problem normally encountered. In a modification, the carrier component is used to transmit data either alone or in combination with the voice signal.
Inventors
- 👤 Theodore Lerner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 20:52
CPC Classifications
H; H04; H04B; H04B14/00; H04B14/002; H04B14/006
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
200 words
A narrowband phase modulation voice communication system characterized by the absence of thresholding effects at useful signal-to-noise ratios, comprising in combination: transmitter means for transmitting a signal having a voice signal component and receiver means for receiving the transmitted signal; said transmitter means including carrier signal generator means for generating a carrier signal of fixed amplitude, voice signal input means for generating a voice signal, and phase modulator means connected to said carrier signal and to said voice signal for producing a resultant signal in the form of a variable amplitude resultant signal having a voice signal component and a fixed amplitude carrier signal component in phase quadrature, said voice signal component having a maximum amplitude whereby said resultant signal has a maximum phase deviation φ which is large with respect to but less than 90° such that sin φ≠φ, and limiter means connected to said phase modulator means for limiting said resultant signal to a constant amplitude signal whereby said carrier signal component is of variable amplitude and said voice signal component is attenuated; and said receiver means including phase locked loop demodulator means for coherently tracking said variable amplitude carrier component to recover said attenuated voice signal component.
Claim 2
Dependent Claim
200 words
A narrowband phase modulation voice communication system characterized by the absence of thresholding effects at useful signal-to-noise ratios, comprising in combination: transmitter means for transmitting a signal having a voice signal component and receiver means for receiving the transmitted signal; said transmitter means including carrier signal generator means for generating a carrier signal of fixed amplitude, voice signal input means for generating a voice signal, and phase modulator means connected to said carrier signal and to said voice signal for producing a resultant signal in the form of a variable amplitude resultant signal having a voice signal component and a fixed amplitude carrier signal component in phase quadrature, said voice signal component having a maximum amplitude whereby said resultant signal has a maximum phase deviation φ which is large with respect to but less than 90° such that sin φ≠φ, and limiter means connected to said phase modulator means for limiting said resultant signal to a constant amplitude signal whereby said carrier signal component is of variable amplitude and said voice signal component is attenuated; and said receiver means including phase locked loop demodulator means for coherently tracking said variable amplitude carrier component to recover said attenuated voice signal component.
Claim 3
Dependent Claim
49 words
A narrowband phase modulation system as defined in claim 1 wherein said transmitter means also includes means for preemphasizing said voice signal prior to quadrature modulation and said receiver means also includes means for deemphasizing the demodulated signal to restore the voice signal and attenuate noise at higher frequencies.
Claim 4
Dependent Claim
43 words
A narrowband phase modulation voice communication system as defined in claim 1 wherein said maximum phase deviation of said resultant signal is in the order of 60° and the 3 dB bandwidth of said tracking loop is in the order of 5000 Hz.
Claim 5
Dependent Claim
105 words
A narrowband phase modulation system according to claim 1 wherein said transmitter means also includes digital data input means for reversing the phase of said carrier component in accord with digital data to be transmitted; and said demodulator means comprises an in-phase detector and a quadrature phase detector both receiving the transmitted signal, a voltage controlled oscillator having an output applied to said in-phase detector, a quadrature phase shifter receiving the output of said voltage controlled oscillator and having an output connected to said quadrature phase detector, a multiplier receiving the outputs of said detectors and having an output connected to said voltage controlled oscillator.
Claim 6
Independent Claim
150 words
The method of voice communicating by means of radiant energy transmission and reception, which comprises the steps of: a. phase modulating a sinusoidal carrier signal with a voice signal to produce a resultant signal which consists of said carrier signal and said voice signal as quadrature components, the maximum amplitude of said voice signal component being sufficiently large with respect to said carrier signal component that the maximum phase deviation φ of said resultant signal with respect to the carrier signal component is less than but large with respect to 90° so that sin φ≠φ; b. hard limiting said resultant signal to provide a constant amplitude resultant signal; c. transmitting said constant amplitude resultant signal at a selected frequency; d. receiving the transmitted signal; and e. demodulating the received signal by coherently tracking its carrier component while recovering its voice signal component whereby the demodulation process is unaffected by thresholding.
Claim 7
Independent Claim
150 words
The method of voice communicating by means of radiant energy transmission and reception, which comprises the steps of: a. phase modulating a sinusoidal carrier signal with a voice signal to produce a resultant signal which consists of said carrier signal and said voice signal as quadrature components, the maximum amplitude of said voice signal component being sufficiently large with respect to said carrier signal component that the maximum phase deviation φ of said resultant signal with respect to the carrier signal component is less than but large with respect to 90° so that sin φ≠φ; b. hard limiting said resultant signal to provide a constant amplitude resultant signal; c. transmitting said constant amplitude resultant signal at a selected frequency; d. receiving the transmitted signal; and e. demodulating the received signal by coherently tracking its carrier component while recovering its voice signal component whereby the demodulation process is unaffected by thresholding.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-10-10 | 1981-04-11 | 1981-10-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-10-10 | 1985-04-11 | 1985-10-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-10-10 | 1989-04-11 | 1989-10-11 | $7700.00 | Window Closed / Lapsed |