US4893341A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Digital receiver operating at sub-nyquist sampling rate
Assignee: Seiko Instruments Inc
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Filing: 1989-08-01
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Granted: 1990-01-09
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Expires: 2009-08-01
Abstract
Abstract A digital receiver samples data from an amplitude modulated subcarrier at a rate less than twice the subcarrier's maximum frequency by sampling at known phase points. Sampling at known phase points is achieved by generating a sampling clock from a signal phase locked to and transmitted with the modulated data subcarrier.
Inventors
- 👤 Mark R. Gehring
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 18:53
CPC Classifications
H; H03; H03D; H03D1/00; H03D1/22; H03D1/2245; H03D1/2254; H04; H04B; H04B1/00; H04B1/06; H04B1/16; H04B1/1646
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
132 words
A receiver for receiving an amplitude modulated subcarrier, said subcarrier being transmitted as part of an RF composite signal that includes a pilot signal, the receiver including: a front end for converting the RF composite signal to a baseband composite signal; a frequency source for producing a sampling clock signal; means for phase locking said frequency source to the pilot signal in the baseband composite signal; sampling means for sampling said composite signal at a rate determined by the sampling clock signal; analog to digital conversion means for converting the samples produced by the sampling means into digital form; digital filter means for digitally filtering said digitized samples to attenuate the non-subcarrier components thereof; wherein said sampling clock signal has a frequency less than twice the maximum frequency of the modulated subcarrier.
Claim 2
Dependent Claim
132 words
A receiver for receiving an amplitude modulated subcarrier, said subcarrier being transmitted as part of an RF composite signal that includes a pilot signal, the receiver including: a front end for converting the RF composite signal to a baseband composite signal; a frequency source for producing a sampling clock signal; means for phase locking said frequency source to the pilot signal in the baseband composite signal; sampling means for sampling said composite signal at a rate determined by the sampling clock signal; analog to digital conversion means for converting the samples produced by the sampling means into digital form; digital filter means for digitally filtering said digitized samples to attenuate the non-subcarrier components thereof; wherein said sampling clock signal has a frequency less than twice the maximum frequency of the modulated subcarrier.
Claim 3
Dependent Claim
31 words
The receiver of claim 1 in which the frequency source includes means for producing a sampling clock signal having a frequency that is an integral multiple of the pilot signal frequency.
Claim 4
Dependent Claim
37 words
The receiver of claim 2 in which: the pilot signal has a frequency of 19 kilohertz; the subcarrier signal has a carrier frequency of 66.5 kilohertz; and the sampling clock signal has a frequency of 133 kilohertz.
Claim 5
Independent Claim
84 words
A method of receiving data that is modulated on a subcarrier of a composite signal, the method comprising the steps: deriving from said composite signal a reference frequency having a known relationship with the subcarrier frequency; sampling the composite signal periodically at certain phase conditions of the reference frequency; digitizing the sampled composite signal to yield digital data; and filtering said digital data to attenuate the non-subcarrier components of the digitized composite signal; wherein said sampling occurs at a frequency twice the subcarrier frequency.
Claim 6
Independent Claim
84 words
A method of receiving data that is modulated on a subcarrier of a composite signal, the method comprising the steps: deriving from said composite signal a reference frequency having a known relationship with the subcarrier frequency; sampling the composite signal periodically at certain phase conditions of the reference frequency; digitizing the sampled composite signal to yield digital data; and filtering said digital data to attenuate the non-subcarrier components of the digitized composite signal; wherein said sampling occurs at a frequency twice the subcarrier frequency.
References Cited (Backward Citations)
US4757538A
Cited
US4688253A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-01-08 | 1993-07-10 | 1994-01-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-01-08 | 1997-07-10 | 1998-01-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-01-08 | 2001-07-10 | 2002-01-09 | $7700.00 | Window Closed / Lapsed |