US4833706A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Ensemble modem structure for imperfect transmission media
Assignee: Telebit Corp
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Filing: 1988-01-05
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Granted: 1989-05-23
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Expires: 2008-01-05
Abstract
Abstract A high-speed modem that transmits and receives digital data on an ensemble of carrier frequencies spanning the usable band of a dial-up telephone line. The modem includes a system for variably allocating data and power among the carriers to compensate for equivalent noise and to maximize the data rate. Additionally, systems for eliminating the need for an equalization network, for adaptively allocating control of a channel, and the tracking variations in line parameters are disclosed.
Inventors
- 👤 Dirk Hughes-Hartogs
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 19:38
CPC Classifications
H; H04; H04L; H04L1/00; H04L1/20; H04L1/206; H04L1/0001; H04L1/0002; H04L1/0003; H04L5/00; H04L5/003; H04L5/0044; H04L5/14; H04L5/16
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
199 words
In a high speed modem communication system having A and B modems coupled by a telephone line, a method for initiating a sampling interval having a given time sample offset equal to the reciprocal of the sampling frequency, said method comprising the steps of: generating an analog waveform at modem A including first and second frequency components at f 1 and f 2 ; transmitting said waveform from modem A to modem B at time T A ; adjusting the phases of said first and and second frequency components so that their relative phase difference at time T A is equal to about 0°; detecting energy at frequency f 1 at modem B to determine the estimated time, T EST , that said waveform arrives at modem B; determing the relative phase difference at modem B between said first and second frequency components at time T EST ; calculating the number of sampling time offsets, N I , required for the relative phase of said first and second carriers to change from 0 to said relative phase difference; and changing the magnitude of T EST by N I sampling intervals to obtain a precise timing reference, T 0 .
Claim 2
Dependent Claim
199 words
In a high speed modem communication system having A and B modems coupled by a telephone line, a method for initiating a sampling interval having a given time sample offset equal to the reciprocal of the sampling frequency, said method comprising the steps of: generating an analog waveform at modem A including first and second frequency components at f 1 and f 2 ; transmitting said waveform from modem A to modem B at time T A ; adjusting the phases of said first and and second frequency components so that their relative phase difference at time T A is equal to about 0°; detecting energy at frequency f 1 at modem B to determine the estimated time, T EST , that said waveform arrives at modem B; determing the relative phase difference at modem B between said first and second frequency components at time T EST ; calculating the number of sampling time offsets, N I , required for the relative phase of said first and second carriers to change from 0 to said relative phase difference; and changing the magnitude of T EST by N I sampling intervals to obtain a precise timing reference, T 0 .
Claim 3
Dependent Claim
210 words
In a high speed modem communication system having A and B modems coupled by a telephone line, a system for initiating a sampling interval having a given time sample offset equal to the reciprocal of the sampling frequency, said system comprising: means for generating an analog waveform at modem A including first and second frequency components at f 1 and f 2 ; means for transmitting said waveform from modem A to modem B at time T A ; means for adjusting the phases of said first and and second frequency components so that their relative phase difference at time T A is equal to about 0°; means for detecting energy at frequency f 1 at modem B to determine the estimated time, T EST , that said waveform arrives at modem B; means for determining the relative phase difference at modem B between said first and second frequency components at time T EST ; means for calculating the number of sampling time offsets, N I , required for the relative phase of said first and second carriers to change from 0 to said relative phase difference; and means for changing the magnitude of T EST by N I sampling intervals to obtain a precise timing reference, T 0 .
Claim 4
Dependent Claim
210 words
In a high speed modem communication system having A and B modems coupled by a telephone line, a system for initiating a sampling interval having a given time sample offset equal to the reciprocal of the sampling frequency, said system comprising: means for generating an analog waveform at modem A including first and second frequency components at f 1 and f 2 ; means for transmitting said waveform from modem A to modem B at time T A ; means for adjusting the phases of said first and and second frequency components so that their relative phase difference at time T A is equal to about 0°; means for detecting energy at frequency f 1 at modem B to determine the estimated time, T EST , that said waveform arrives at modem B; means for determining the relative phase difference at modem B between said first and second frequency components at time T EST ; means for calculating the number of sampling time offsets, N I , required for the relative phase of said first and second carriers to change from 0 to said relative phase difference; and means for changing the magnitude of T EST by N I sampling intervals to obtain a precise timing reference, T 0 .
References Cited (Backward Citations)
US4206320A
Cited
US4438511A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-05-22 | 1992-11-21 | 1993-05-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-05-22 | 1996-11-21 | 1997-05-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-05-22 | 2000-11-21 | 2001-05-23 | $7700.00 | Window Closed / Lapsed |