US3568078A
Expired / Lapsed
US
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Fm demodulators with signal error removal
Assignee: Radiation Inc
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Filing: 1968-12-23
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Granted: 1971-03-02
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Expires: 1988-12-23
Abstract
Abstract An FM demodulator system for improved reception of FM signals at low input signal-to-noise ratios by estimation of the error in the demodulated signal and subtraction of this estimated error from the demodulator output to provide a stronger output.
Inventors
- 👤 Guy Majella Pelchat
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 20:56
CPC Classifications
H; H03; H03D; H03D3/00; H03D3/001; H03D3/002
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
154 words
A demodulator network for frequency modulated signals, said network comprising means for demodulating an incoming frequencymodulated signal, means responsive to the demodulated signal and any error waveform thereon for frequency modulation thereof to generate a second frequency-modulated signal consisting of a carrier frequency modulated by said demodulated signal and error waveform, means responsive to said second frequency-modulated signal and to a delay equalized version of said incoming frequency-modulAted signal for mixing thereof to cancel said demodulated signal and thereby to produce a third frequencymodulated signal in which the carrier is frequency modulated substantially only by said error waveform, means for demodulating said third frequency modulated signal to extract said error waveform an estimate of the error in the original demodulated signal, and means for subtractively combining the extracted error waveform with a delay-equalized version of the original demodulated signal and the actual error waveform associated therewith to produce a substantially error-free demodulated output signal.
Claim 2
Dependent Claim
154 words
A demodulator network for frequency modulated signals, said network comprising means for demodulating an incoming frequencymodulated signal, means responsive to the demodulated signal and any error waveform thereon for frequency modulation thereof to generate a second frequency-modulated signal consisting of a carrier frequency modulated by said demodulated signal and error waveform, means responsive to said second frequency-modulated signal and to a delay equalized version of said incoming frequency-modulAted signal for mixing thereof to cancel said demodulated signal and thereby to produce a third frequencymodulated signal in which the carrier is frequency modulated substantially only by said error waveform, means for demodulating said third frequency modulated signal to extract said error waveform an estimate of the error in the original demodulated signal, and means for subtractively combining the extracted error waveform with a delay-equalized version of the original demodulated signal and the actual error waveform associated therewith to produce a substantially error-free demodulated output signal.
Claim 3
Dependent Claim
15 words
The invention according to claim 1 wherein the last-named demodulating means is an FM discriminator.
Claim 4
Dependent Claim
19 words
The invention according to claim 1 wherein said means for combining is included in the last-named means for demodulating.
Claim 5
Dependent Claim
99 words
An FM demodulator network comprising means for demodulating an incoming FM signal; means responsive to the demodulated signal and any error waveform associated therewith and to the original incoming FM signal, delay equalized with the demodulated signal, to generate a carrier frequency modulated by said error waveform; means for demodulating said modulated carrier frequency to obtain an estimate of said error waveform; and means for applying said estimated error waveform to a correspondingly timed replica of the initially demodulated signal with actual error waveform to substantially cancel said actual error waveform thereby lower the reception threshold of said network.
Claim 6
Dependent Claim
99 words
An FM demodulator network comprising means for demodulating an incoming FM signal; means responsive to the demodulated signal and any error waveform associated therewith and to the original incoming FM signal, delay equalized with the demodulated signal, to generate a carrier frequency modulated by said error waveform; means for demodulating said modulated carrier frequency to obtain an estimate of said error waveform; and means for applying said estimated error waveform to a correspondingly timed replica of the initially demodulated signal with actual error waveform to substantially cancel said actual error waveform thereby lower the reception threshold of said network.
Claim 7
Dependent Claim
19 words
The invention according to claim 4 wherein said means for applying is included in the last-named means for demodulating.
Claim 8
Dependent Claim
96 words
A demodulator network for angle modulated signal, comprising: means for demodulating said signal; means responsive to the demodulated signal and any error waveform associated therewith and to the original incoming signal, delay equalized with the demodulated signal, to produce a carrier signal modulated by said error waveform; means for detecting said error waveform from said carrier signal as an estimate of the actual error waveform; and means for subtracting the estimated error from a delay-equalized replica of said demodulated signal with its actual error waveform, to substantially remove the actual error waveform from the demodulated signal.
Claim 9
Dependent Claim
96 words
A demodulator network for angle modulated signal, comprising: means for demodulating said signal; means responsive to the demodulated signal and any error waveform associated therewith and to the original incoming signal, delay equalized with the demodulated signal, to produce a carrier signal modulated by said error waveform; means for detecting said error waveform from said carrier signal as an estimate of the actual error waveform; and means for subtracting the estimated error from a delay-equalized replica of said demodulated signal with its actual error waveform, to substantially remove the actual error waveform from the demodulated signal.
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) | 1974-03-01 | 1974-08-31 | 1975-03-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-03-01 | 1978-08-31 | 1979-03-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-03-01 | 1982-08-31 | 1983-03-02 | $7700.00 | Window Closed / Lapsed |