Patent US2312792A successfully refreshed from Google Patents.
Patent US4123625A successfully refreshed from Google Patents.
US4123625A
Expired / Lapsed
US
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Digital regenerator having improving noise immunity
Assignee: Nortel Networks Ltd
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Filing: 1977-11-03
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Granted: 1978-10-31
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Expires: 1997-11-03
Abstract
Abstract A digital repeater for the regeneration of partial-response signals having improved noise immunity which basically comprises an equalizer followed by a regenerator. A band limiting filter disposed between the equalizer and regenerator transforms the partial-response signal to a modified form having the same or fewer levels and concurrently reduces the total power of the noise interference. A second filter disposed after the regenerator and having an inverse transfer function replicates the partial-response signal at its output so that the repeater appears transparent to the transmission line.
Inventors
- 👤 Peter E. K. Chow
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 19:31
CPC Classifications
H; H04; H04L; H04L25/00; H04L25/02; H04L25/20; H04L25/24; H04L25/242; H04L25/38; H04L25/40; H04L25/49; H04L25/497
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
203 words
In a digital repeater for regenerating a partial-response signal from a transmission line, the signal being subject to noise interference having a power density which varies with frequency, said repeater comprising: an equalizer responsive to the signal from the transmission line for equalizing the transfer characteristics of the transmission line; and a regenerator responsive to the output of the equalizer for regenerating said partial-response signal; the improvement comprising: a first filter disposed between the equalizer and the regenerator to introduce intersymbol interference so as to transform the partial-response signal to a ternary partial-response signal, in which the product R(jω) of frequency characteristic of the partial-response signal S(jω) and the transfer function of the first filter H(jω) is equal to: R(jω) = S(jω) H(jω) = 1 -ε.sup.-jNωiT where: T = pulse repetition period of the partialresponse signal, iT = unit delay of each filter tap, N = total number of filter taps, said first filter band-limiting the overall power of the noise interference; and a second filter disposed between the regenerator and the output of the digital repeater having a transfer function which is the inverse of said first filter so as to derive a replica of said partial-response signal at the output thereof.
Claim 2
Dependent Claim
203 words
In a digital repeater for regenerating a partial-response signal from a transmission line, the signal being subject to noise interference having a power density which varies with frequency, said repeater comprising: an equalizer responsive to the signal from the transmission line for equalizing the transfer characteristics of the transmission line; and a regenerator responsive to the output of the equalizer for regenerating said partial-response signal; the improvement comprising: a first filter disposed between the equalizer and the regenerator to introduce intersymbol interference so as to transform the partial-response signal to a ternary partial-response signal, in which the product R(jω) of frequency characteristic of the partial-response signal S(jω) and the transfer function of the first filter H(jω) is equal to: R(jω) = S(jω) H(jω) = 1 -ε.sup.-jNωiT where: T = pulse repetition period of the partialresponse signal, iT = unit delay of each filter tap, N = total number of filter taps, said first filter band-limiting the overall power of the noise interference; and a second filter disposed between the regenerator and the output of the digital repeater having a transfer function which is the inverse of said first filter so as to derive a replica of said partial-response signal at the output thereof.
Claim 3
Dependent Claim
19 words
A digital repeater as defined in claim 1 in which the equalized channel response has a raised-cosine frequency characteristic.
Claim 4
Dependent Claim
25 words
A digital repeater as defined in clAim 2 in which: ##EQU2## H(jω) = [1 - ε.sup.-j(ωiT + aπ) ] where: a = 0 or 1
Claim 5
Dependent Claim
47 words
A digital repeater as defined in claim 3 in which the second filter additionally comprises: logic circuitry for forcing a digit of preselected magnitude and polarity at the output of the second filter in response to the detection of a predetermined sequence of digits in the repeater.
Claim 6
Dependent Claim
152 words
In a digital repeater for regenerating a partial-response signal from a transmission line, the signal being subject to noise interference having a power density which varies with frequency, said repeater comprising: an equalizer responsive to the signal from the transmission line for equalizing the transfer characteristics of the transmission line; and a regenerator responsive to the output of the equalizer for regenerating said partial-response signal; the improvement comprising: a first filter, disposed between the equalizer and the regenerator, to band limit the overall power of the noise interference, and to introduce intersymbol interference so as to transform the partial-response signal to a modified partial-response signal having the same or fewer levels; and a second filter disposed betwen the regenerator and the output of the digital repeater having a transfer function which is the inverse of said first filter so as to derive a replica of said partial-response signal at the output thereof.
Claim 7
Dependent Claim
152 words
In a digital repeater for regenerating a partial-response signal from a transmission line, the signal being subject to noise interference having a power density which varies with frequency, said repeater comprising: an equalizer responsive to the signal from the transmission line for equalizing the transfer characteristics of the transmission line; and a regenerator responsive to the output of the equalizer for regenerating said partial-response signal; the improvement comprising: a first filter, disposed between the equalizer and the regenerator, to band limit the overall power of the noise interference, and to introduce intersymbol interference so as to transform the partial-response signal to a modified partial-response signal having the same or fewer levels; and a second filter disposed betwen the regenerator and the output of the digital repeater having a transfer function which is the inverse of said first filter so as to derive a replica of said partial-response signal at the output thereof.
Claim 8
Dependent Claim
22 words
A digital repeater as defined in claim 5 in which the partial-response signal and the modified partial-response signal are both ternary level.
Claim 9
Dependent Claim
18 words
A digital repeater as defined in claim 6 in which the channel response has a raised-cosine amplitude characteristic.
Claim 10
Dependent Claim
47 words
A digital repeater as defined in claim 7 in which the second filter additionally comprises: logic circuitry for forcing a pulse of preselected magnitude and polarity at the output of the second filter in response to the detection of a predetermined sequence of pulses in the repeater.
Claim 11
Dependent Claim
124 words
In a digital repeater for regenerating a partial-response signal, subject to noise interference having a power density which varies with frequency, said repeater comprising: a regenerator for regenerating said partial-response signal; the improvement comprising: a first filter disposed between the input of the digital repeater and the regenerator to introduce intersymbol interference so as to transform the partial-response signal to a modified partial-response signal having not more than the same number of levels, the filter reducing the overall power of the noise interference; and a second filter disposed between the regenerator and the output of the digital repeater having a transfer function which is the inverse of said first filter so as to derive a replica of said partial-response signal at the output thereof.
Claim 12
Dependent Claim
124 words
In a digital repeater for regenerating a partial-response signal, subject to noise interference having a power density which varies with frequency, said repeater comprising: a regenerator for regenerating said partial-response signal; the improvement comprising: a first filter disposed between the input of the digital repeater and the regenerator to introduce intersymbol interference so as to transform the partial-response signal to a modified partial-response signal having not more than the same number of levels, the filter reducing the overall power of the noise interference; and a second filter disposed between the regenerator and the output of the digital repeater having a transfer function which is the inverse of said first filter so as to derive a replica of said partial-response signal at the output thereof.
Claim 13
Dependent Claim
22 words
A digital repeater as defined in claim 9 in which the partial-response signal and the modified partial-response signal are both ternary level.
Claim 14
Dependent Claim
80 words
In a regenerating circuit for regenerating a partial-response signal, subject to noise interference having a power density which varies with frequency, said circuit comprising: a regenerator for regenerating said partial-response signal; the improvement comprising: a filter disposed between the input of the circuit and the regenerator for introducing intersymbol interference so as to transform the partial-response signal to a modified partial-response signal having not more than the same number of levels, the filter reducing the power of the noise interference.
Claim 15
Dependent Claim
80 words
In a regenerating circuit for regenerating a partial-response signal, subject to noise interference having a power density which varies with frequency, said circuit comprising: a regenerator for regenerating said partial-response signal; the improvement comprising: a filter disposed between the input of the circuit and the regenerator for introducing intersymbol interference so as to transform the partial-response signal to a modified partial-response signal having not more than the same number of levels, the filter reducing the power of the noise interference.
Claim 16
Dependent Claim
172 words
In a digital repeater for regenerating a bipolar signal received from a transmission line, the signal being subject to near-end crosstalk interference, said repeater comprising: an equalizer responsive to the signal from the transmission line for equalizing the transfer characteristics of the transmission line to obtain a channel response having a raised-cosine amplitude characteristic: and a regenerator responsive to the output of the equalizer for regenerating the signal coupled thereto; the improvement comprising: a first filter disposed between the equalizer and regenerator and having a transfer function; H(jω) = 2 cos ωT/2(ε.sup.-(jωT/2)) where: T = pulse repetition rate of the bipolar signal; so as to introduce intersymbol interference and transform the bipolar signal to a modified duobinary signal, and so as to reduce the overall power of the near-end crosstalk from the transmission line; and a second filter disposed between the regenerator and the output of the digital repeater having a transfer funcion: H.sup.-1 (jω) = 1/2secωT/2 (ε.sup.(ωT/2)) so as to derive a replica of said bipolar signal at the outuput thereof.
Claim 17
Dependent Claim
172 words
In a digital repeater for regenerating a bipolar signal received from a transmission line, the signal being subject to near-end crosstalk interference, said repeater comprising: an equalizer responsive to the signal from the transmission line for equalizing the transfer characteristics of the transmission line to obtain a channel response having a raised-cosine amplitude characteristic: and a regenerator responsive to the output of the equalizer for regenerating the signal coupled thereto; the improvement comprising: a first filter disposed between the equalizer and regenerator and having a transfer function; H(jω) = 2 cos ωT/2(ε.sup.-(jωT/2)) where: T = pulse repetition rate of the bipolar signal; so as to introduce intersymbol interference and transform the bipolar signal to a modified duobinary signal, and so as to reduce the overall power of the near-end crosstalk from the transmission line; and a second filter disposed between the regenerator and the output of the digital repeater having a transfer funcion: H.sup.-1 (jω) = 1/2secωT/2 (ε.sup.(ωT/2)) so as to derive a replica of said bipolar signal at the outuput thereof.
Claim 18
Dependent Claim
73 words
A digital repeater as defined in claim 12 in which the second filter is a digital filter and additionally includes: logic circuitry for forcing a logical 0 at the digital filter output concurrently with the detection of the third digit of either of the sequences X + + or X - - at the input to the second filter where X is a different level than the latter two levels of each sequence.
Claim 19
Dependent Claim
51 words
A digital repeater as defined in claim 13 in which the second filter includes additional logic circuitry for forcing a logical 0 or 1 at the digital filter output in response to the detection of at least three consecutive logical 0's or 1's respectively, at the input to the first filter.
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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) | 1981-10-30 | 1982-05-01 | 1982-10-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-10-30 | 1986-05-01 | 1986-10-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-10-30 | 1990-05-01 | 1990-10-31 | $7700.00 | Window Closed / Lapsed |