US4555790A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Digital modem having a monitor for signal-to-noise ratio
Assignee: Paradyne Corp
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Filing: 1983-06-30
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Granted: 1985-11-26
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Expires: 2003-06-30
Abstract
Abstract The present invention pertains to a digital modem utilizing QAM-type modulation having a signal-to-noise monitor which utilizes some of the components of a standard modem without interfering with its normal operation. The monitor averages the absolute value of the difference between the signal received by the modem and the ideal signal as represented on a typical signal constellation. In order to minimize the effect of phase and amplitude errors the monitor only handles the innermost signals of the constellation and ignores all the other signals.
Inventors
- 👤 William L. Betts
- 👤 Kenneth Martinez
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 11:35
CPC Classifications
H; H04; H04L; H04L1/00; H04L1/20; H04L1/206; H04L27/00; H04L27/32; H04L27/34; H04L27/38
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
113 words
A modem with a signal-to-noise ratio monitor in a digital communication system utilizing QAM- type modulation adapted to receive signals which can be represented as a signal constellation, comprising: means for determining ideal signals each one of said ideal signals corresponding to a received signal, and; enabling means for enabling a monitoring means only when said received signals are the innermost signals with respect to the origin of said signal constellation; said monitoring means comprising: means for generating a noise signal for said received signals, said noise signal being equal to the difference between said received signals and the corresponding ideal signals; and means for generating the rms value of said noise signals.
Claim 2
Dependent Claim
113 words
A modem with a signal-to-noise ratio monitor in a digital communication system utilizing QAM- type modulation adapted to receive signals which can be represented as a signal constellation, comprising: means for determining ideal signals each one of said ideal signals corresponding to a received signal, and; enabling means for enabling a monitoring means only when said received signals are the innermost signals with respect to the origin of said signal constellation; said monitoring means comprising: means for generating a noise signal for said received signals, said noise signal being equal to the difference between said received signals and the corresponding ideal signals; and means for generating the rms value of said noise signals.
Claim 3
Dependent Claim
16 words
The modem of claim 1 wherein said enabling means are a part of said determining means.
Claim 4
Dependent Claim
21 words
The modem of claim 1 wherein said rms value generating means comprise; an absolute value means; and a digital low-pass filter.
Claim 5
Dependent Claim
19 words
The modem of claim 3 wherein said digital low-pass filter is adapted to be enabled by said enabling means.
References Cited (Backward Citations)
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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) | 1988-11-25 | 1989-05-27 | 1989-11-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-11-25 | 1993-05-27 | 1993-11-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-11-25 | 1997-05-27 | 1997-11-26 | $7700.00 | Window Closed / Lapsed |