EP0927471A1 - Circuit hybride - Google Patents

Circuit hybride

Info

Publication number
EP0927471A1
EP0927471A1 EP98902928A EP98902928A EP0927471A1 EP 0927471 A1 EP0927471 A1 EP 0927471A1 EP 98902928 A EP98902928 A EP 98902928A EP 98902928 A EP98902928 A EP 98902928A EP 0927471 A1 EP0927471 A1 EP 0927471A1
Authority
EP
European Patent Office
Prior art keywords
resistors
rqt
hybrid circuit
rqr
impedance
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.)
Withdrawn
Application number
EP98902928A
Other languages
German (de)
English (en)
Inventor
Stefan RÜEGSEGGER
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens Schweiz AG
Original Assignee
Siemens Schweiz AG
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Siemens Schweiz AG filed Critical Siemens Schweiz AG
Publication of EP0927471A1 publication Critical patent/EP0927471A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L5/00—Arrangements affording multiple use of the transmission path
    • H04L5/14—Two-way operation using the same type of signal, i.e. duplex
    • H04L5/1423—Two-way operation using the same type of signal, i.e. duplex for simultaneous baseband signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
    • H04B1/40—Circuits
    • H04B1/54—Circuits using the same frequency for two directions of communication
    • H04B1/58—Hybrid arrangements, i.e. arrangements for transition from single-path two-direction transmission to single-direction transmission on each of two paths or vice versa
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B3/00—Line transmission systems
    • H04B3/02—Details
    • H04B3/03—Hybrid circuits
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
    • H04B1/40—Circuits
    • H04B1/54—Circuits using the same frequency for two directions of communication
    • H04B1/58—Hybrid arrangements, i.e. arrangements for transition from single-path two-direction transmission to single-direction transmission on each of two paths or vice versa
    • H04B1/581—Hybrid arrangements, i.e. arrangements for transition from single-path two-direction transmission to single-direction transmission on each of two paths or vice versa using a transformer
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/38—Transceivers, i.e. devices in which transmitter and receiver form a structural unit and in which at least one part is used for functions of transmitting and receiving
    • H04B1/40—Circuits
    • H04B1/54—Circuits using the same frequency for two directions of communication
    • H04B1/58—Hybrid arrangements, i.e. arrangements for transition from single-path two-direction transmission to single-direction transmission on each of two paths or vice versa
    • H04B1/583—Hybrid arrangements, i.e. arrangements for transition from single-path two-direction transmission to single-direction transmission on each of two paths or vice versa using a bridge network

Definitions

  • the present invention relates to a hybrid circuit according to the preamble of claim 1.
  • switches or hybrid circuits are used, such as are used e.g. in Steinbuch / Rupprecht, communications engineering, Springer-Verlag, Heidelberg 1982, 3rd edition, volume 2, pages 46 - 52 or Hertert örcher, communications engineering, Hanser Verlag, Kunststoff 1994, 7th edition, pages 72 and 329.
  • Fork circuits are e.g. used in amplifier circuits, which are inserted between sections of two-wire lines for the necessary raising of the signal level of the bidirectionally transmitted signals.
  • hybrid circuits are provided on the subscriber or exchange side in order to route the transmitted signals from a two-wire transmission line to a receiving amplifier and the signals to be transmitted from a transmission amplifier to the transmission line (see, for example, LW Couch, DIGITAL AND ANALOG COMMUNICATION SYSTEMS, Prentice- Hall Inc. 1997, pages 536-543 or).
  • An important requirement for the hybrid circuit is that no portion of the output signal of the transmit amplifier may reach the input of the receive amplifier.
  • FIG. 1 shows a passive hybrid circuit known from Siemens, IC's for Communications, ISDN Echocancellation Circuit, IEC-Q, PEB 2091 - Version 4.3, User's Manual 02.95, Figure 83 (Hybrid Circuit), in which the outputs of a transmitter unit or a transmitting amplifier TX each via a resistor Rqt or Rqr and the inputs of a receiving unit or a receiving amplifier RX, which has an internal resistance Rr, are each connected via a resistor R3t or R3r to the connections of a transformer TF which connects the hybrid circuit with connects a transmission line which has an impedance ZI.
  • Hybrid Circuit Hybrid Circuit
  • the reception amplifier RX is supplied with an inverted portion (correction portion) of the transmission signal from the outputs of the transmission amplifier TX via resistors R1t and R2t or R1 r and R2r.
  • a point-symmetrical structure of the resistance bridge is provided with respect to the input of the receive amplifier RX, the resistors of the compensation path being weighted in accordance with the correction component to be provided. It must be taken into account that the interference component is influenced by the line impedance ZI.
  • a corresponding balance impedance Zb is therefore provided in the correction branch of the hybrid circuit.
  • the balance impedance Zb consists of a 681 ohm resistor, which is connected in series to connect a 3.01 kOhm resistor and a 6.8 nF capacitor in parallel.
  • the disadvantage of this circuit is that a relatively large number of resistors is required, the values of which must be selected precisely. Furthermore, the balance impedance Zb is to be selected in each case in accordance with the transmission line used or with the characteristic impedance ZI of the transmission line.
  • the present invention is therefore based on the object of providing a simplified switching circuit which does not require a balance impedance Zb.
  • the hybrid circuit according to the invention which does not require a balance impedance Zb, has a simplified circuit structure and can therefore be manufactured inexpensively. Since no balance impedance Zb is required, the control circuit can be connected to different transmission lines without adjustments. The elimination of any interference that may occur in the low-frequency range is carried out with a simple filter for all normally used transmission lines. Calibrations or adaptations of the hybrid circuit according to the invention due to the tolerances of the components or when the diameter of the transmission line changes are therefore eliminated. Furthermore, the hybrid circuit according to the invention is particularly suitable for receiving units which have a relatively low input resistance.
  • FIG. 3 shows the typical phase profile of a transmission line as a function of frequency
  • FIG. 4 shows a hybrid circuit according to the invention
  • FIG. 6 shows a hybrid circuit according to the invention with the filter switched on
  • FIG. 7 shows a possible embodiment of the filter according to FIG. 6,
  • FIG. 8 shows a known hybrid circuit with active echo cancellation and
  • FIG. 9 the hybrid circuit according to FIG. 8 with passive echo cancellation according to the invention.
  • Fig. 1 shows the hybrid circuit described above, which has a balance impedance Zb.
  • Zb the magnitude of the resistance IZII of a transmission line from 10,000 Hz to 20,000 Hz is typically in the range of 135 ohms.
  • the phase curve also moves in this area by 0 °.
  • compensation of the resistance and phase characteristics of the transmission line can therefore be dispensed with, or an ohmic resistance can be used for Zb, which according to the invention is eliminated by scaling the resistance bridge, but the symmetry of the resistance bridge must be preserved. This is done by scaling the resistance bridge in such a way that the value to be set for the balance resistor Zb moves towards infinity until the balance resistor Zb loses its influence on the correction component and is therefore no longer required.
  • the values of the resistors R1t, R1r, R2t, R2r, R3t, R3r are also selected such that the transmitted signal from the corresponding voltage dividers reaches the input of the receive amplifier RX without significant reduction.
  • the value R of the resistors R1t, R1r, R2t, R2r, R3t, R3r is to be selected around 10 to 100 times larger than the value of the resistors Rqr and Rqt, which is approximately 1 when the transformer ratio is 1: 1 / 2 IZII corresponds.
  • the resistors R1t and R2t or R1r and R2r are combined to form a resistor R4t or R4r, which has the value 2R.
  • the hybrid circuit according to the invention is also advantageously connected to the receiving unit RX via a filter FR.
  • the present invention is therefore based on the object of specifying measures which, without occasional adaptations, allow transmission links for high data transmission rates to be implemented using copper cables, as are present in the connection area of communication networks.
  • copper cables of different lengths and diameters can be used for the construction of HDSL transmission links without the need to adapt further components of the transmission system to the cable properties .
  • the use of commercially available components of the transmission system e.g. commercially available HDSL components
  • FIG. 2 shows a possible embodiment of a filter provided for dynamic limitation.
  • FIG. 3a shows the basic circuit diagram of a known HDSL transmission path
  • 3b shows the basic circuit diagram of an HDSL transmission link according to the invention for simplex operation
  • FIG. 3c the basic circuit diagram of an HDSL transmission link according to the invention for duplex operation; and FIG. 4 frequency-dependent curves of the signal attenuation of two copper cables with the same length and the same line diameter.
  • connection area of Telecom networks there are copper cables that differ in length, insulation materials as well as the distance and diameter of the wire pairs, and thus different line properties (resistance, inductance, capacitance, lead cover as well as world resistance).
  • copper cables with lengths of up to 7 km and diameters of approximately 0.4 mm to 1.4 mm are present in the connection area of communication networks.
  • Fig. 1 shows the course of the attenuation distortion (attenuation curve depending on the frequency) of copper cables SL1, SL2 and SL3 with diameters of 0.4 mm, 1, 0 mm and 1, 4 mm, the lengths of which are chosen such that they are Frequency of around 220 kHz have the same attenuation.
  • the 1.4 mm cable SL1 with the same length in the entire frequency range has a lower attenuation than the 0.4 mm cable SL3, as shown in FIG. 4. It can be seen from the diagram in FIG.
  • the 1.4 mm cable SL1 has a much lower attenuation in the range of lower frequencies ( ⁇ 10 4 Hz) and a significantly higher attenuation in the range of high frequencies (> 10 5 Hz), than the 0.4 mm cable SL3.
  • the 0.4 mm cable SL3 has an attenuation that is around 10 dB greater than that of the 1.4 mm cable SL1.
  • a signal transmitted via the 1.4 mm cable SL1 therefore has a dynamic range that is around 10 dB higher (see dynl ⁇ dyn2) than a signal transmitted via the 0.4 mm cable SL3.
  • the filter FR which corresponds, for example, to the RC filter shown in FIG. 2, which is constructed in a known manner with capacitors Cf and resistors Rf, preferably has an attenuation curve as shown in FIG. 1
  • 3a shows the basic circuit diagram of the HDSL transmission path known from COMTEC, Technical Communications of CH-Telecom, 2/1997, page 28, which shows a line termination HDSL / LT which is connected via subscriber connection cables SL1, ..., SL3 with a network termination HDSL / NT is connected, from which individual base connection lines are led away.
  • 3b shows the basic circuit diagram of an HDSL transmission link according to the invention for simplex operation. From the line termination LTSX, data from transmission units TX are transmitted in simplex mode via the subscriber connection cables SL1, ..., SL3 to the network termination NTSX or a filter FR provided for dynamic compensation and further to receiving units RX.
  • the data transmission between line and network termination LTDX and NTDX takes place in a known manner in duplex mode via hybrid circuits GS, a filter FR serving for dynamic compensation being provided between a hybrid circuit GS and the associated receiving unit RX.
  • the filter FR can also advantageously be used together with integrated receiving units RX, which may be part of a transceiver. Suitable are, for example, the SK70704 / SK70707 from LEVEL ONE, which are described in the associated data sheet, "1168 kbps HDSL Data Pump Chip Set", from May 1996.
  • the curves of the attenuation as a function of frequency are shown for cables with different diameters (0.4 mm; 1.0 mm and 1.4 mm). These are typically pure copper cables, as they are mostly installed in telephone networks.
  • the diagram shows that cables with a larger diameter have a much lower attenuation in the range of lower frequencies ( ⁇ 10 4 Hz) and a significantly higher attenuation in the range of high frequencies (> 10 5 Hz) than cables with a correspondingly smaller diameter.
  • the 0.4 mm cable has a 10 dB greater attenuation than the 1.4 mm diameter cable.
  • the attenuation of these two cables is almost identical.
  • a signal transmitted via the 1.4 mm cable therefore has a dynamic range that is around 10 dB higher (see dynl ⁇ dyn2) than a signal transmitted via the 0.4 mm cable.
  • a filter FR is therefore provided in the circuit arrangements according to FIGS. 6, 7 and 9, by means of which the signal components in the range of lower frequencies ( ⁇ 10 4 Hz) are reduced by around 10 dB.
  • the filter FR which corresponds, for example, to the filter shown in FIG. 7, preferably has a damping curve as shown in FIG. 5 (see the curve of line fkl). From this it can be seen that signals in the range up to 1000 Hz are reduced by around 10 dB by the FR filter.
  • the dynamic range of the signals transmitted via the 1.4 mm cable is adapted to the dynamic range of the signals transmitted via the 0.4 mm cable. If, however, a 0.4 mm cable is connected to the hybrid circuit in accordance with FIG. 6, FIG. 7 or FIG. 9, the signal components in the range of lower frequencies ( ⁇ 10 4 Hz) do not become below the signal level of the signal components in the range higher Frequencies (10 4 Hz - 10 5 Hz) lowered, which would result in a reduced signal-to-noise ratio.
  • the circuit arrangement according to the invention can therefore be used for all installed copper cables, the analog-digital converter not having to have a greater resolution.
  • the circuit arrangement shown in FIG. 8, which has an active transmission circuit G1 is known from the data sheet from LEVEL ONE in May 1996 for the SK70704 / SK70707 modules, which can be used as "1168 kbps HDSL Data Pump Chip Set" (see in particular Page 8, Fig. 3 and page 26, Fig. 13 of the data sheet).
  • the signal to be transmitted is fed to the transmitter TF via a scrambler (scrambler) SCR, an encoder ENC, a filter TXF, an amplifier LD and resistors Rqt and Rqr.
  • the transmitted signals are transmitted from the transformer TF via resistors Rc and Rd, a first addition stage S1, a subsequent differential stage DIFF, an analog-to-digital converter ADC and a third connected to a digital echo canceller
  • Addition stage S3 fed to an equalizer circuit ETR.
  • the differential stage DIFF is supplied with a corresponding inverted portion (correction portion) of the transmission signal from the output of the amplifier LD via resistors Ra and Rb and a second addition stage S2. This compensates for the interference or echo component contained in the input signal.
  • complex resistors Za and Zb are provided in the reception path and in the correction path. If the diameter of the transmission line changes, there is insufficient compensation of the interference or echo component by the correction component unless the complex resistors Za or Zb are adjusted accordingly.
  • signal distortion can also occur at the output of the ADC analog-to-digital converter, provided that it does not have a correspondingly high resolution.
  • the elements are also designated (see ⁇ -IC) which are contained in the above-mentioned integrated circuits.
  • the same integrated circuit is connected to the hybrid circuit g2 according to the invention shown in FIG. 6, the advantages of which are particularly clear in this case too.
  • the hybrid circuit G2 according to the invention in turn allows the connection of transmission lines with different diameters without circuit adjustments. It is also permissible to use an ADC analog-to-digital converter with reduced resolution. Losses resulting from passive echo compensation and filtering can be easily compensated for by means of the integrated circuit IC in that the output signal of the filter FR is supplied to the first addition stage S1 in an inverted manner and to the second addition stage S2 in an inverted manner. In the differential stage, therefore, the in-phase addition of the signals present at the addition stages S1 and S2 takes place.
  • the invention can also be used for hybrid circuits without a transformer TF.

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)

Abstract

L'invention concerne un circuit hybride qui sert à raccorder une unité d'émission (TX) et une unité de réception (RX) à une ligne de transmission bifilaire. Ce circuit hybride comprend un circuit en pont avec quatre branches comportant chacune deux résistances (R1t, R2t; R1r, R2r; R3r, Rqr; R3t, Rqt) qui relient les deux sorties (txa1, txa2) de l'unité d'émission (TX) et les deux entrées (rxe1,rxe2) de l'unité de réception (RX) et sont conçues de sorte que les composantes du signal d'émission, apparaissant à l'entrée de l'unité de réception (RX), se compensent les unes les autres. On raccorde la ligne de transmission, éventuellement en intercalant un transformateur (TF), par l'intermédiaire des premières résistances (Rqt et Rqr) de la troisième et de la quatrième branche de pont (R3r, Rqr; R3t, Rqt), à l'unité d'émission (TX), et par l'intermédiaire des deuxièmes résistances (R3t et R3r) de la troisième et de la quatrième branche de pont (R3r, Rqr; R3t, Rqt), à l'unité de réception (RX). Selon l'invention, les résistances (R1t, R2t, R3r, Rqr ou R1r, R2r, R3t, Rqt) des quatre branches de pont sont sélectionnées de sorte qu'une impédance (Zb) à prévoir fondamentalement pour compenser l'impédance (ZI) de la ligne de transmission présente une valeur si élevée que la tolérance aux défaillances prévue pour le circuit hybride est respectée même sans montage de cette impédance (Zb). De préférence, ce circuit hybride est raccordé à l'entrée de l'unité de réception (RX) par un filtre (FR) qui sert à équilibrer les dynamiques (dyn1, dyn2) des signaux qui sont transmis par l'intermédiaire de câbles présentant différents diamètres.
EP98902928A 1997-03-25 1998-02-26 Circuit hybride Withdrawn EP0927471A1 (fr)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
CH71497 1997-03-25
CH71497 1997-03-25
CH75697 1997-04-02
CH75697 1997-04-02
PCT/CH1998/000077 WO1998043385A1 (fr) 1997-03-25 1998-02-26 Circuit hybride

Publications (1)

Publication Number Publication Date
EP0927471A1 true EP0927471A1 (fr) 1999-07-07

Family

ID=25685457

Family Applications (1)

Application Number Title Priority Date Filing Date
EP98902928A Withdrawn EP0927471A1 (fr) 1997-03-25 1998-02-26 Circuit hybride

Country Status (4)

Country Link
EP (1) EP0927471A1 (fr)
AU (1) AU730313B2 (fr)
NO (1) NO985487L (fr)
WO (1) WO1998043385A1 (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1429466B1 (fr) * 2002-12-13 2005-09-14 Alcatel Circuit hybride de télécommunication dépendante de la fréquence
US6931122B2 (en) 2003-02-05 2005-08-16 Analog Devices, Inc. Single transformer hybrid system and method

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6042959A (ja) * 1983-08-19 1985-03-07 Fuji Facom Corp 差動型同時双方向伝送回路
FR2677196A1 (fr) * 1991-05-31 1992-12-04 Sgs Thomson Microelectronics Convertisseur differentiel passif deux fils/quatre fils.

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO9843385A1 *

Also Published As

Publication number Publication date
WO1998043385A1 (fr) 1998-10-01
NO985487D0 (no) 1998-11-24
NO985487L (no) 1999-01-25
AU5979898A (en) 1998-10-20
AU730313B2 (en) 2001-03-01

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