CA1164548A - Repeater for a digital transmission system - Google Patents
Repeater for a digital transmission systemInfo
- Publication number
- CA1164548A CA1164548A CA000368254A CA368254A CA1164548A CA 1164548 A CA1164548 A CA 1164548A CA 000368254 A CA000368254 A CA 000368254A CA 368254 A CA368254 A CA 368254A CA 1164548 A CA1164548 A CA 1164548A
- Authority
- CA
- Canada
- Prior art keywords
- output
- repeater
- coupled
- filter
- out circuit
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L25/00—Baseband systems
- H04L25/02—Details ; arrangements for supplying electrical power along data transmission lines
- H04L25/03—Shaping networks in transmitter or receiver, e.g. adaptive shaping networks
- H04L25/03006—Arrangements for removing intersymbol interference
- H04L25/03012—Arrangements for removing intersymbol interference operating in the time domain
- H04L25/03019—Arrangements for removing intersymbol interference operating in the time domain adaptive, i.e. capable of adjustment during data reception
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
- Dc Digital Transmission (AREA)
Abstract
A. Jessop et al 7-4-1-1 (Revision) Abstract of the Disclosure A repeater for PCM ox digital transmission systems includes, in addition to the usual primary feedback control loop, a secondary feedback control loop having a low-pass filter and a peak detector to derive a control signal for a controllable impedance in the equalizer circuit. This control loop optimizes the repeater performance fox different cable types and characteristics with regard to the low frequency energy content of the eye diagram.
ACH/mlw/jn November 17, 1980
ACH/mlw/jn November 17, 1980
Description
5~L~
A. Jessop-R J Catchpole- !.;;.:
P.J. Dyke~B.5. Farley 7-~-1-1 ~Revision) :.......
, ......
,,",.,',:', .......
.,,,,,:.".
,. .. ...
.::.
,:: ::
. :,: ., ':,'':'''', : ., .
,::
A REPEATER FOR A DIGITAL TRAIISMISSIO~ SYSTEM
, .
Back~round of the Invention This invention relates to repeaters for PCM (pulse code modulation) or digital transmission svstems, and more -~
particularly to arrangements for compensating therein for -~
transmission line characteristics.
Conventional automatic line build out (ALBO) networ~s provide variable eqùalization within a primary equalization :
feedback control loop to correct for mainly frequency dependent losses due to line length variations. However, changes in cable type, e.g., paper insulated, plastics insulated, etc., in cable characteristics and signal level variations all e~fect the performance o~ repe~ters. The ~.
. . .
use of high efficiency line codes, such as that known as 4B3T and disclosed in U.S. Patent 3,611,141, issued October 5, 1971, requires accurate equaIization of line losses, especially at lower frequencies where this code :
contains more energy than codes, such as that known as HDB3 (~igh Density B;polar 3~, whether Gr not the signals are scrambled.
A known equalizer design for heavily multiplexed PCM
systems, e.g., 48 channels at 2.37M bit/sec, for example, is shown in Fig. 1. This design incorporates a primary equali-zation control loop to keep the height of the so-called "eye 1f"
diagram" constant, with the ALBO network carefully designed to give correct equalization for a range of different line .....
.......
i 3~
L6~4~
lengths. The equalized signal is taken from a decision point X and applied to an ALB0 peak detector 10, which detects the peak or "height" of the eye diagram. This peak value is amplified and fed to a diode network 11. The output of diode network 11 is used to control the ~LB0 network equalization.
When the repeaters are manufactured a manually adjustable variable resistor is included in network 12 to enable the repeater, once installed, to be adjusted for the lo~ frequency content of the eye diagram An object of the present invention is to provide an improved arrangement in a repeater for a PCM or digital transmission system to compensate for transmission line characteristics.
According to a first aspect of the present invention, there is proyided a feedback control loop for an equalization network in a repeater ; of a digital transmission line~system comprising: a filter coupled to the output of said network responsive to equalized signals at the output of said network, and a peak detector coupled to the output of said filter responsive to a continuous low frequency voltage output of said filter to produce a control slgnal for controlling a controllable impedance included in said network.
According to a second aspect of the present invention, there is provided a repeater for a digital transmission line system comprising: an automatic line build out circuit having a primary equalization feedback , control loop coupled between an output of said line build out circuit and a irst controllable impedance means connec~ed in said line build out circuit, said primary feedback control loop being responsive to equalized signals at said output of said line build out circuit; and an equalizer circuit having its output coupled to an input of said line build out cir-cuit, said equalizer circuit having at least one secondary feedback control loop coupled to said output of said line build out circuit, sald secondary loop being resporlsive to said equalized signals including a filter coupled to said output of said line build out circuit and a first peak detector coupled to the output of said filter to produce a control signal to control ~J a second controllable impedance means connected in said equalizer circuit.
s~
In a preferred embodiment the secondary loop filter is a low pass filter.
According to a third aspect of the invention, there is provided a method of equalization for a digital transmission line rep~ater compri~
sing the steps of filtering equalized signals within a control loop; and detecting peak values of said filtered equali~ed signals to provide a control signal for controlling equali~ation in said repeater.
The above-mentioned and other features and objects of this invention will become more apparent by reference to the following descrip-tion taken in conjunction with the accompanying drawing~ in which:
~J
-2a-A. Jessop et al 7-4 ~ic~. 1 is a bloc}; diagram of the prior art equali-zation arrangement described hereinabove under the heading "~ack~round o~ the Invention"; and Fig. 2 is a block diagram of a repeater equalization arrangement in accordance with the principles of the present invention.
escription of the Preferred Embodiment The repeater of Fig~ 2 is basically the repeater of Fig. 1 with the addition of the secondary control loop. The equalized si~nals rom decision point X are fed to a low-pass filter 20 which is followed by a peak detector 21. The output of peak ; detector 21 is amplified and ~ed as a control signal to a variable impedance 22 in equalizer 13. The low pass filter 20 ensures that the secondary loop only responds to the low frequency content of the eye diagram or control of equalizer 13. This automatic control of equalizer 13 optimizes the equaliæation for thebest eye diagram, regardless of the cable type or characteristic of the input cable.
While we have described above the principles of our invention in connection with specific apparatus, it is to be `~ clearly understood th~t this description is made only by way of ex~ample and not as a limitation to the scope of our inventicn as set Cor~h in the objects thereof and in the accompanying claims.
ACH/mlW/jn November 17, 1980 .......
.......
A. Jessop-R J Catchpole- !.;;.:
P.J. Dyke~B.5. Farley 7-~-1-1 ~Revision) :.......
, ......
,,",.,',:', .......
.,,,,,:.".
,. .. ...
.::.
,:: ::
. :,: ., ':,'':'''', : ., .
,::
A REPEATER FOR A DIGITAL TRAIISMISSIO~ SYSTEM
, .
Back~round of the Invention This invention relates to repeaters for PCM (pulse code modulation) or digital transmission svstems, and more -~
particularly to arrangements for compensating therein for -~
transmission line characteristics.
Conventional automatic line build out (ALBO) networ~s provide variable eqùalization within a primary equalization :
feedback control loop to correct for mainly frequency dependent losses due to line length variations. However, changes in cable type, e.g., paper insulated, plastics insulated, etc., in cable characteristics and signal level variations all e~fect the performance o~ repe~ters. The ~.
. . .
use of high efficiency line codes, such as that known as 4B3T and disclosed in U.S. Patent 3,611,141, issued October 5, 1971, requires accurate equaIization of line losses, especially at lower frequencies where this code :
contains more energy than codes, such as that known as HDB3 (~igh Density B;polar 3~, whether Gr not the signals are scrambled.
A known equalizer design for heavily multiplexed PCM
systems, e.g., 48 channels at 2.37M bit/sec, for example, is shown in Fig. 1. This design incorporates a primary equali-zation control loop to keep the height of the so-called "eye 1f"
diagram" constant, with the ALBO network carefully designed to give correct equalization for a range of different line .....
.......
i 3~
L6~4~
lengths. The equalized signal is taken from a decision point X and applied to an ALB0 peak detector 10, which detects the peak or "height" of the eye diagram. This peak value is amplified and fed to a diode network 11. The output of diode network 11 is used to control the ~LB0 network equalization.
When the repeaters are manufactured a manually adjustable variable resistor is included in network 12 to enable the repeater, once installed, to be adjusted for the lo~ frequency content of the eye diagram An object of the present invention is to provide an improved arrangement in a repeater for a PCM or digital transmission system to compensate for transmission line characteristics.
According to a first aspect of the present invention, there is proyided a feedback control loop for an equalization network in a repeater ; of a digital transmission line~system comprising: a filter coupled to the output of said network responsive to equalized signals at the output of said network, and a peak detector coupled to the output of said filter responsive to a continuous low frequency voltage output of said filter to produce a control slgnal for controlling a controllable impedance included in said network.
According to a second aspect of the present invention, there is provided a repeater for a digital transmission line system comprising: an automatic line build out circuit having a primary equalization feedback , control loop coupled between an output of said line build out circuit and a irst controllable impedance means connec~ed in said line build out circuit, said primary feedback control loop being responsive to equalized signals at said output of said line build out circuit; and an equalizer circuit having its output coupled to an input of said line build out cir-cuit, said equalizer circuit having at least one secondary feedback control loop coupled to said output of said line build out circuit, sald secondary loop being resporlsive to said equalized signals including a filter coupled to said output of said line build out circuit and a first peak detector coupled to the output of said filter to produce a control signal to control ~J a second controllable impedance means connected in said equalizer circuit.
s~
In a preferred embodiment the secondary loop filter is a low pass filter.
According to a third aspect of the invention, there is provided a method of equalization for a digital transmission line rep~ater compri~
sing the steps of filtering equalized signals within a control loop; and detecting peak values of said filtered equali~ed signals to provide a control signal for controlling equali~ation in said repeater.
The above-mentioned and other features and objects of this invention will become more apparent by reference to the following descrip-tion taken in conjunction with the accompanying drawing~ in which:
~J
-2a-A. Jessop et al 7-4 ~ic~. 1 is a bloc}; diagram of the prior art equali-zation arrangement described hereinabove under the heading "~ack~round o~ the Invention"; and Fig. 2 is a block diagram of a repeater equalization arrangement in accordance with the principles of the present invention.
escription of the Preferred Embodiment The repeater of Fig~ 2 is basically the repeater of Fig. 1 with the addition of the secondary control loop. The equalized si~nals rom decision point X are fed to a low-pass filter 20 which is followed by a peak detector 21. The output of peak ; detector 21 is amplified and ~ed as a control signal to a variable impedance 22 in equalizer 13. The low pass filter 20 ensures that the secondary loop only responds to the low frequency content of the eye diagram or control of equalizer 13. This automatic control of equalizer 13 optimizes the equaliæation for thebest eye diagram, regardless of the cable type or characteristic of the input cable.
While we have described above the principles of our invention in connection with specific apparatus, it is to be `~ clearly understood th~t this description is made only by way of ex~ample and not as a limitation to the scope of our inventicn as set Cor~h in the objects thereof and in the accompanying claims.
ACH/mlW/jn November 17, 1980 .......
.......
Claims (7)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A repeater for a digital transmission line system comprising:
an automatic line build out circuit having a primary equalization feedback control loop coupled between an output of said line build out circuit and a first controllable impedance means connected in said line build out circuit, said primary feedback control loop being responsive to equalized signals at said output of said line build out circuit; and an equalizer circuit having its output coupled to an input of said line build out circuit, said equalizer circuit having at least one secondary feedback control loop coupled to said output of said line build out circuit, said secondary loop being responsive to said equalized signals including a filter coupled to said output of said line build out circuit and a first peak detector coupled to the output of said filter to produce a control signal to control a second controllable impedance means connected in said equalizer circuit.
an automatic line build out circuit having a primary equalization feedback control loop coupled between an output of said line build out circuit and a first controllable impedance means connected in said line build out circuit, said primary feedback control loop being responsive to equalized signals at said output of said line build out circuit; and an equalizer circuit having its output coupled to an input of said line build out circuit, said equalizer circuit having at least one secondary feedback control loop coupled to said output of said line build out circuit, said secondary loop being responsive to said equalized signals including a filter coupled to said output of said line build out circuit and a first peak detector coupled to the output of said filter to produce a control signal to control a second controllable impedance means connected in said equalizer circuit.
2. A-repeater according to claim 1, wherein said filter is a low pass filter.
3. A repeater according to claims 1 or 2, wherein said primary loop includes a second peak detector having its input coupled to said output of said line build out circuit and its output coupled to said first controllable impedance means to control said line build out circuit.
A. Jessup et al 7-4-1-1
A. Jessup et al 7-4-1-1
4. A method of equalization for a digital transmission line repeater comprising the steps of filtering equalized signals within a control loop; and detecting peak values of said filtered equalized signals to provide a control signal for controlling equalization in said repeater.
5. A method according to claim 4, wherein said step of filtering includes the step of low pass filtering said equalized signals.
6. A feedback control loop for an equalization network in a repeater of a digital transmission line system comprising:
a filter coupled to the output of said network responsive to equalized signals at the output of said network; and a peak detector coupled to the output of said filter responsive to a continuous low frequency voltage output of said filter to produce a control signal for controlling a controllable impedance included in said network.
a filter coupled to the output of said network responsive to equalized signals at the output of said network; and a peak detector coupled to the output of said filter responsive to a continuous low frequency voltage output of said filter to produce a control signal for controlling a controllable impedance included in said network.
7. A control loop according to claim 6, wherein said filter is a low pass filter.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8001632 | 1980-01-17 | ||
| GB8001632A GB2068196B (en) | 1980-01-17 | 1980-01-17 | Repeaters for digital transmission systems |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1164548A true CA1164548A (en) | 1984-03-27 |
Family
ID=10510705
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000368254A Expired CA1164548A (en) | 1980-01-17 | 1981-01-09 | Repeater for a digital transmission system |
Country Status (11)
| Country | Link |
|---|---|
| JP (1) | JPS56106439A (en) |
| AU (1) | AU538667B2 (en) |
| CA (1) | CA1164548A (en) |
| CH (1) | CH651977A5 (en) |
| DE (1) | DE3047906A1 (en) |
| ES (1) | ES498535A0 (en) |
| FR (1) | FR2474260A1 (en) |
| GB (1) | GB2068196B (en) |
| IT (1) | IT1194020B (en) |
| NL (1) | NL8100055A (en) |
| SE (1) | SE442933B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3241813A1 (en) * | 1982-11-11 | 1984-05-17 | Siemens Ag | AUTOMATIC EQUALIZER ARRANGEMENT ADJUSTING THE CABLE LENGTH |
| US4785265A (en) * | 1987-10-01 | 1988-11-15 | The Babcock & Wilcox Company | Enhanced automatic line build out |
| US5132926A (en) * | 1990-09-21 | 1992-07-21 | Proteon, Inc. | Token ring equalizer |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB721941A (en) * | 1951-01-12 | 1955-01-19 | Gen Electric Co Ltd | Improvements in or relating to electrical communication systems |
| US3568100A (en) * | 1967-12-26 | 1971-03-02 | Bell Telephone Labor Inc | Automatic equalizer for digital transmission systems |
| JPS527304B1 (en) * | 1969-08-29 | 1977-03-01 | ||
| GB1304910A (en) * | 1970-08-05 | 1973-01-31 | ||
| US3728649A (en) * | 1972-04-24 | 1973-04-17 | Bell Telephone Labor Inc | Automatic equalizer for digital cable transmission systems |
| US3824501A (en) * | 1973-07-12 | 1974-07-16 | Bell Telephone Labor Inc | Automatic cable equalizer |
| GB1520810A (en) * | 1975-12-18 | 1978-08-09 | Gen Electric Co Ltd | Regenerative repeaters for digital transmission systems |
-
1980
- 1980-01-17 GB GB8001632A patent/GB2068196B/en not_active Expired
- 1980-12-19 DE DE19803047906 patent/DE3047906A1/en not_active Ceased
- 1980-12-22 AU AU65642/80A patent/AU538667B2/en not_active Ceased
-
1981
- 1981-01-08 NL NL8100055A patent/NL8100055A/en not_active Application Discontinuation
- 1981-01-09 SE SE8100095A patent/SE442933B/en not_active IP Right Cessation
- 1981-01-09 CA CA000368254A patent/CA1164548A/en not_active Expired
- 1981-01-15 CH CH237/81A patent/CH651977A5/en not_active IP Right Cessation
- 1981-01-15 ES ES498535A patent/ES498535A0/en active Granted
- 1981-01-15 FR FR8100612A patent/FR2474260A1/en active Granted
- 1981-01-16 JP JP396381A patent/JPS56106439A/en active Granted
- 1981-01-19 IT IT19191/81A patent/IT1194020B/en active
Also Published As
| Publication number | Publication date |
|---|---|
| GB2068196B (en) | 1984-02-15 |
| CH651977A5 (en) | 1985-10-15 |
| ES8202217A1 (en) | 1982-01-01 |
| JPS56106439A (en) | 1981-08-24 |
| GB2068196A (en) | 1981-08-05 |
| DE3047906A1 (en) | 1981-09-17 |
| FR2474260B1 (en) | 1984-12-28 |
| IT1194020B (en) | 1988-08-31 |
| SE442933B (en) | 1986-02-03 |
| SE8100095L (en) | 1981-07-18 |
| AU6564280A (en) | 1981-07-23 |
| AU538667B2 (en) | 1984-08-23 |
| IT8119191A0 (en) | 1981-01-19 |
| NL8100055A (en) | 1981-08-17 |
| JPS6352502B2 (en) | 1988-10-19 |
| ES498535A0 (en) | 1982-01-01 |
| FR2474260A1 (en) | 1981-07-24 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4254305A (en) | Current limited subscriber line feed circuit | |
| US5708703A (en) | Wide range equalizer with line length detection | |
| EP0086838B1 (en) | High-sensitivity fm signal demodulation system | |
| US4592068A (en) | Repeater for a digital transmission system | |
| US3510793A (en) | Amplifier regulator employing an electrolytic variable resistance device | |
| US2193966A (en) | Volume range controlling arrangement employing thermionic amplifiers | |
| JPH0681082B2 (en) | Method and circuit arrangement for compensating crosstalk and / or echo signals | |
| US4555788A (en) | Multiple rate baseband receiver | |
| US5455843A (en) | Adaptive equalizing apparatus and method for token ring transmission systems using unshielded twisted pair cables | |
| CA1164548A (en) | Repeater for a digital transmission system | |
| US4201959A (en) | Automatic equalization system | |
| US4538283A (en) | Adaptive equalizer suitable for use with fiber optics | |
| US4821286A (en) | Quaternary signal regenerator | |
| US4488126A (en) | Equalizer arrangement for mixed-gauge cables | |
| EP0086839B1 (en) | High-sensitivity fm demodulating system | |
| EP0040660B1 (en) | Equalizing apparatus for data transmission lines | |
| US4746881A (en) | Equalizer for frequency independent and dependent transmission loss components with a pilot used for the frequency independent component | |
| US4087639A (en) | Amplitude modulated telephone carrier systems | |
| US4555789A (en) | Equalizer circuit suitable for adaptive use with fiber optics | |
| GB2094592A (en) | Adaptive equaliser | |
| US3801911A (en) | Synchronous fm-modem | |
| US4378535A (en) | Adaptive equalizer for short distance metallic circuits | |
| US4229625A (en) | Repeater level control circuit | |
| JP3741955B2 (en) | Apparatus and method for controlling sampling rate in a data transmission system | |
| CA1238432A (en) | Digital radio communication system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |