US3766480A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Device for recovering a frequency showing phase jitter
Assignee: International Business Machines Corp
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Filing: 1972-01-19
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Granted: 1973-10-16
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Expires: 1992-01-19
Abstract
Abstract Frequency shift and phase jitter impressed on angle modulated signal spectra during long distance transmission is eliminated at the receiver where the data spectra exclusive of the harmonically related pilot frequencies is time and phase delayed by a discrete amount in a data recovery path. At the same time, a demodulation frequency is extracted from the signal spectrum in a carrier recovery path, the demodulation frequency being the sum of the pilot frequencies. Relatedly, the demodulation frequency is time and phase delayed in the carrier recovery path by an amount equal to that of the data path. Demodulation of the data spectra thus subtractively eliminates the frequency shift and jitter components.
Inventors
- 👤 J Pierret
- 👤 J Belloc
- 👤 M Choquet
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 08:00
CPC Classifications
H; H04; H04L; H04L27/00; H04L27/02; H04L27/06; H04L27/066; H03; H03D; H03D1/00; H03D1/02; H03D1/04; H03D1/22; H03D1/24; H03D3/00; H03D3/001; H03D3/002; H03D7/00; H03D7/16; H03D7/161; H03D7/163; H03D7/165
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
177 words
In a receiver of phase modulated signals in which each signal as received has its spectral components frequency shifted by s hertz and phase jitter time modulated by Delta phi (t) radians, the spectrum including harmonically related pilot frequencies f1 and f2 lying outside the data frequency band f, where f2 nf1, and wherein the improvement comprises: a first signal processing path responsive to the received data frequency band f + s + K Delta phi (t), K being a constant, for respectively time and phase delaying each frequency by Tau seconds and phi radians whereby the data band becomes f + s + K1 Delta phi (t- Tau ) + K2 phi , K1 and K2 being constants; a second signal processing path for extracting a demodulation frequency f1'' + f2 + s + K1 Delta phi (t- Tau ) + K2 phi from each received signal spectrum where f1'' f2 - f1/n-1; and means for demodulating the first path spectral output by the demodulation frequency thereby subtractively eliminating the frequency shift and phase jitter components.
Claim 2
Dependent Claim
177 words
In a receiver of phase modulated signals in which each signal as received has its spectral components frequency shifted by s hertz and phase jitter time modulated by Delta phi (t) radians, the spectrum including harmonically related pilot frequencies f1 and f2 lying outside the data frequency band f, where f2 nf1, and wherein the improvement comprises: a first signal processing path responsive to the received data frequency band f + s + K Delta phi (t), K being a constant, for respectively time and phase delaying each frequency by Tau seconds and phi radians whereby the data band becomes f + s + K1 Delta phi (t- Tau ) + K2 phi , K1 and K2 being constants; a second signal processing path for extracting a demodulation frequency f1'' + f2 + s + K1 Delta phi (t- Tau ) + K2 phi from each received signal spectrum where f1'' f2 - f1/n-1; and means for demodulating the first path spectral output by the demodulation frequency thereby subtractively eliminating the frequency shift and phase jitter components.
Claim 3
Dependent Claim
96 words
In a receiver according to claim 1, wherein the second signal processing path includes: means for forming a jitter free frequency f1'' according to the relation f1'' (f2 + s + K Delta phi (t) - f1 + s + K Delta phi (t);)/(n-1) means for forming the demodulation frequency f1'' + f2 + s + K Delta phi (t); and means for time and phase delaying the demodulation frequency by Tau seconds and phi radians whereby the frequency becomes f1'' + f2 + s + K1 Delta phi (t- Tau ) + K2 phi .
Claim 4
Dependent Claim
71 words
In a receiver according to claim 2, wherein the means for forming the jitter free frequency f1'' include: a first switched filter responsive to each received signal spectrum for extracting the pilot frequency f2 + s + K Delta phi (t); means for modulating the received signal spectrum with the extracted pilot frequency for obtaining the difference frequency f2 - f1; and counting means for dividing the difference frequency by n-1.
Claim 5
Dependent Claim
23 words
In a receiver according to claim 2, wherein the time and phase delaying means include: a phase locked oscillator with a phase shifter.
Claim 6
Dependent Claim
66 words
In a receiver according to claim 1, wherein the first signal processing path includes: a pilot frequency rejection filter for passing each data frequency band f + s + K Delta phi (t); a delta coder for digitizing the filtered signal; a shift register imposing a Tau second delay on the digitized signal; and a delta decoder for recombining the delayed digits into an analog signal.
Claim 7
Dependent Claim
131 words
In a receiver of phase modulated signals in which each signal as received has its spectral components frequency shifted and phase jitter time modulated, the spectrum includes a pair of harmonically related pilot frequencies lying outside the data frequency band, wherein the improvement comprises: a first signal processing path for time and phase delaying by predetermined amounts the frequency shifted and jitter modulated data frequency band; a second signal processing path for extracting a demodulation frequency from each signal equal to the sum of the pilot frequencies, said demodulation frequency being frequencY shifted, jitter modulated, time and phase delayed by an amount matching that of the first signal path; and means for demodulating the data frequency band by the demodulation frequency thereby subtractively eliminating the frequency shift and phase jitter components.
Claim 8
Dependent Claim
131 words
In a receiver of phase modulated signals in which each signal as received has its spectral components frequency shifted and phase jitter time modulated, the spectrum includes a pair of harmonically related pilot frequencies lying outside the data frequency band, wherein the improvement comprises: a first signal processing path for time and phase delaying by predetermined amounts the frequency shifted and jitter modulated data frequency band; a second signal processing path for extracting a demodulation frequency from each signal equal to the sum of the pilot frequencies, said demodulation frequency being frequencY shifted, jitter modulated, time and phase delayed by an amount matching that of the first signal path; and means for demodulating the data frequency band by the demodulation frequency thereby subtractively eliminating the frequency shift and phase jitter components.
Claim 9
Dependent Claim
79 words
In a receiver according to claim 6, wherein the second path includes: means for forming a frequency shift free and jitter free low pilot frequency; means for combining the low pilot frequency with the high pilot frequency, whereby the combined frequency exhibits only the same frequency shift and phase jitter as that attributed to the data frequency band; and means for adjusting the time and phase delay of the combined frequency to match that of the data frequency band.
References Cited (Backward Citations)
US3349329A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-10-15 | 1977-04-16 | 1977-10-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-15 | 1981-04-16 | 1981-10-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-15 | 1985-04-16 | 1985-10-16 | $7700.00 | Window Closed / Lapsed |