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US3568100A
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Automatic equalizer for digital transmission systems
Assignee: AT&T Inc
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Filing: 1967-12-26
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Granted: 1971-03-02
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Expires: 1987-12-26
Abstract
Abstract An automatic equalizer for digital transmission systems includes a variable equalizing network having a transfer characteristic with substantially flat loss, a fixed pole, and a variable zero, an amplifier connected to receive the output from the equalizing network and having substantially flat gain and a fixed zero substantially coincident in frequency with and canceling the fixed pole of the equalizing network, and a peak detector connected to receive the output from the amplifier and control both the flat loss and the frequency of the variable zero of the equalizing network.
Inventors
- 👤 Richard A Tarbos
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 13:25
CPC Classifications
H; H04; H04L; H04L25/00; H04L25/02; H04L25/03; H04L25/03006; H04L25/03012; H04L25/03019
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
85 words
An automatic equalizer for a digital transmission system which comprises an equalizing circuit connected to receive incoming pulses and having a transfer characteristic with substantially flat gain and at least one variable zero, a peak detector connected to generate an output proportional to the peak amplitude of the output of said equalizing circuit, and means to vary both the magnitude of the flat gain and the frequency of the variable zero of said equalizing circuit under the control of the output of said peak detector.
Claim 2
Dependent Claim
85 words
An automatic equalizer for a digital transmission system which comprises an equalizing circuit connected to receive incoming pulses and having a transfer characteristic with substantially flat gain and at least one variable zero, a peak detector connected to generate an output proportional to the peak amplitude of the output of said equalizing circuit, and means to vary both the magnitude of the flat gain and the frequency of the variable zero of said equalizing circuit under the control of the output of said peak detector.
Claim 3
Dependent Claim
131 words
An automatic equalizer for a digital transmission system, which comprises, an equalizing network connected to receive incoming pulses and having a transfer characteristic with substantially flat loss, a fixed pole and at least one variable zero, and an amplifier connected to receive the output of said equalizing network and having a transfer characteristic with substantially flat gain and a fixed zero substantially coinciding in frequency with and canceling the fixed pole of said equalizing network, a peak detector connected to receive the output of said amplifier to generate an output proportional to the peak amplitude of said equalizing network, and means to vary both the magnitude of the flat gain and the frequency of the variable zero of said equalizing network under the control of the output of said peak detector.
Claim 4
Dependent Claim
131 words
An automatic equalizer for a digital transmission system, which comprises, an equalizing network connected to receive incoming pulses and having a transfer characteristic with substantially flat loss, a fixed pole and at least one variable zero, and an amplifier connected to receive the output of said equalizing network and having a transfer characteristic with substantially flat gain and a fixed zero substantially coinciding in frequency with and canceling the fixed pole of said equalizing network, a peak detector connected to receive the output of said amplifier to generate an output proportional to the peak amplitude of said equalizing network, and means to vary both the magnitude of the flat gain and the frequency of the variable zero of said equalizing network under the control of the output of said peak detector.
Claim 5
Dependent Claim
34 words
An automatic equalizer in accordance with claim 2 in which the frequency of the variable zero of said equalizing network is variable upward from the frequency of the fixed pole of said equalizing network.
Claim 6
Dependent Claim
57 words
An automatic equalizer in accordance with claim 3 in which said amplifier is a differential amplifier with a pair of inputs and in which the output of said equalizing network is supplied to one of said inputs and the fixed pole is determined by a feedback path from the amplifier output to the other of said inputs.
Claim 7
Dependent Claim
76 words
An automatic equalizer in accordance with claim 3 in which said equalizing network comprises a two port network with a series resistor connecting one terminal of one port to one terminal of a second port and a shunt circuit shunting both ports said shunt path comprising a variable resistance in series with the parallel combination of a resistance and a capacitance and in which said variable resistance is controlled by the output of said peak detector.
Claim 8
Dependent Claim
18 words
An automatic equalizer in accordance with claim 5 in which said variable resistance is a current-sensitive variable resistance.
Claim 9
Dependent Claim
19 words
An automatic equalizer in accordance with claim 5 in which said variable resistance comprises at least one semiconductor diode.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-03-01 | 1974-08-31 | 1975-03-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-03-01 | 1978-08-31 | 1979-03-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-03-01 | 1982-08-31 | 1983-03-02 | $7700.00 | Window Closed / Lapsed |