US3728649A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic equalizer for digital cable transmission systems
Assignee: AT&T Inc
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Filing: 1972-04-24
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Granted: 1973-04-17
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Expires: 1992-04-24
Abstract
Abstract An automatic equalizer for digital cable transmission systems compares the differentiated and peak detected pulse output of a variable equalizer to an output level of a voltage reference source to produce a first control signal. A second control signal is derived from the first control signal and both control signals vary the amount of equalization provided by the variable equalizer to equalize the incoming pulses from a remote station. The relationship of the two control signals enables one signal path of the variable equalizer, which contains three signal paths, to be used alone or in combination with one of the other two signal paths. The other two signal paths provide transfer characteristics which alter the transfer characteristic of the transmission cable such that the effective electrical length of the cable is either increased or decreased and an appropriately equalized pulse output is available from the variable equalizer.
Inventors
- 👤 F Waldhauer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 15:42
CPC Classifications
H; H04; H04L; H04L25/00; H04L25/02; H04L25/03; H04L25/03006; H04L25/03012; H04L25/03019
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
143 words
In a cable transmission system, an automatic equalizer comprising: variable equalizer means for receiving incoming pulses from a cable connected to a remote station; means for controlling said variable equalizer means to change the effective electrical length of said cable independent of the energy and sequence of the incoming pulses comprising, differentiating means for generating an output indicative of the rate of change in the transitions in the pulse output of said variable equalizer, peak detecting means connected to generate an output proportional to the peak amplitude of the output of said differentiating means, a voltage reference source having an output voltage indicative of the slope of an incoming pulse after being subjected to optimum equalization, and biasing means for comparing the output of said peak detector to the output of said voltage source to vary the equalization of said variable equalizer means.
Claim 2
Dependent Claim
143 words
In a cable transmission system, an automatic equalizer comprising: variable equalizer means for receiving incoming pulses from a cable connected to a remote station; means for controlling said variable equalizer means to change the effective electrical length of said cable independent of the energy and sequence of the incoming pulses comprising, differentiating means for generating an output indicative of the rate of change in the transitions in the pulse output of said variable equalizer, peak detecting means connected to generate an output proportional to the peak amplitude of the output of said differentiating means, a voltage reference source having an output voltage indicative of the slope of an incoming pulse after being subjected to optimum equalization, and biasing means for comparing the output of said peak detector to the output of said voltage source to vary the equalization of said variable equalizer means.
Claim 3
Dependent Claim
133 words
In a cable transmission system the automatic equalizer of claim 1 wherein said variable equalizer means comprises: a first signal path including an amplifier having an input connected to receive the incoming pulses and an output; a second signal path including an amplifier having an input connected to receive the incoming pulses and an output connected to an RC network having an output and simulating a cable loss path; a third signal path including an amplifier having an input connected to receive the incoming pulses and an output connected to an RC network having an output and simulating a cable equalizer path; summing means to combine the outputs of the said signal paths; said biasing means varying the gain of said amplifiers to vary the amount of equalization of said variable equalizer means.
Claim 4
Dependent Claim
72 words
In a cable transmission system, the automatic equalizer of claim 1 wherein said biasing means comprises a differential amplifier having one input connected to receive the output of said peak detecting means and another connected to receive the output of said voltage reference source; filtering means being connected to the output of said differential amplifier; the output of said filtering means being used to vary the equalization of said variable equalizer means.
Claim 5
Dependent Claim
55 words
In a cable transmission system, the automatic equalizer of claim 3 wherein said biasing means further comprises an inverter means being connected to receive the output of said filtering means and said voltage reference source to produce an output signal that increases in magnitude as the output signal of said filtering means decreases in magnitude.
Claim 6
Dependent Claim
168 words
In a cable transmission system, the automatic equalizer of claim 4 wherein said variable equalizer means comprises: a first signal path including an amplifier connected to receive the incoming pulses; a second signal path including an amplifier connected to receive the incoming pulses and to an RC network capable of reducing the effective electrical length of said cable; a third signal path including an amplifier connected to receive the incoming pulses and to aN RC network capable of increasing the effective electrical length of said cable; summing means to combine the output of each signal path; the output of said filtering means being connected to control the gain of said amplifier in the second signal path; the output of said inverting means being connected to control the gain of said amplifier in the third signal path; and the output characteristic of said filtering means and said inverting means enables the first signal path to be used alone or in combination with either said second or third signal paths.
References Cited (Backward Citations)
US3578914A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-04-16 | 1976-10-16 | 1977-04-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-16 | 1980-10-16 | 1981-04-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-16 | 1984-10-16 | 1985-04-17 | $7700.00 | Window Closed / Lapsed |