EP1848008A2 - Câble XDSL - Google Patents

Câble XDSL Download PDF

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Publication number
EP1848008A2
EP1848008A2 EP20070300943 EP07300943A EP1848008A2 EP 1848008 A2 EP1848008 A2 EP 1848008A2 EP 20070300943 EP20070300943 EP 20070300943 EP 07300943 A EP07300943 A EP 07300943A EP 1848008 A2 EP1848008 A2 EP 1848008A2
Authority
EP
European Patent Office
Prior art keywords
conductors
cable
diameter
xdsl
copper
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Withdrawn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
EP20070300943
Other languages
German (de)
English (en)
Inventor
Miguel Morante
Susana Camara
Thomas Haehner
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.)
Nexans SA
Original Assignee
Nexans SA
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
Priority claimed from EP06300377A external-priority patent/EP1848007A1/fr
Application filed by Nexans SA filed Critical Nexans SA
Priority to EP20070300943 priority Critical patent/EP1848008A2/fr
Publication of EP1848008A2 publication Critical patent/EP1848008A2/fr
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B11/00—Communication cables or conductors
    • H01B11/002—Pair constructions
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
    • H01B11/00—Communication cables or conductors
    • H01B11/005—Quad constructions

Definitions

  • the technical domain of the invention is the domain of telephone cables.
  • the invention concerns a cable dedicated to numerical transmissions and optimized for xDSL systems.
  • xDSL digital transmission systems
  • XDSL is a new technology using existing telephone networks and cables to transmit data between interconnected users with high bit rate. All traditional telephone operators have long established telephone cable specifications, which define nominal and minimal requirements for cables to be installed in their networks. These specifications have been initially built up to offer a satisfactory telephone service, the frequency range of which is limited to 3400 Hz or sometimes up to 4000 Hz on some networks.
  • xDSL The problem of xDSL is to sustain a highest possible data bit rate to cope with today more and more demanding applications.
  • xDSL systems allow the transmission of several Mbit/s of data. For that purpose they are using frequency bands up to several MHz.
  • the most advanced xDSL systems are expected to operate at frequencies up to 30 MHz, albeit on short distances. Higher frequencies could also be considered.
  • the context of use differs heavily from the one of the telephone application.
  • US 2005/173144 discloses a cable having twisted conductors for use in digital systems.
  • the cable uses simultaneously a series of pitches having a maximum and minimum value between 10 and 80 mm and a conductor insulation with a thickness from 2.0 to 2.2 times the conductor diameter for a dielectric constant of 1.87.
  • the special sequence of pitches provides a decrease in attenuation and an improvement concerning the problem of cross talk in digital transmission.
  • That document addresses the same problem of enhancing electrical characteristics of communication cables for digital data transmission.
  • a totally different approach is used in that the pitch is varying according to a geometrical progression.
  • the invention instead uses a constant pitch as usual in the art of cables.
  • the present invention addresses and solves this problem.
  • the object of the invention is a xDSL cable comprising a plurality of stranded groups of individually insulated copper conductors inserted in a sheath, either conductors having a copper diameter of 0.4 +/- 0.05 mm and the PSACR of the cable being more than or equal 30dB measured at a frequency of 1 MHz and for a length of 1 km, or conductors having a copper diameter of 0.5 +/- 0.05 mm and the PSACR of the cable being more than or equal 34dB measured at a frequency of 1 MHz and for a length of 1 km and stranded groups having a constant twist lay length of more than or equal 20 mm.
  • the proposed solution advantageously offers the possibility to produce cables with a significant increase of xDSL performance at a much lower cost than the cables (data type) envisaged and used by most applications.
  • Such cables advantageously allow xDSL traffics with bits rates up to 100% higher than the prior art cables, especially at long distances.
  • the conductors of these cables may be stranded by pairs or by quads.
  • the ratio of the diameter of insulation to the diameter of a copper conductor is more than or equal 1.8 for quad grouped conductors.
  • the ratio of the diameter of insulation to the diameter of a copper conductor is more than or equal 1.9 for pair grouped conductors.
  • the cable further comprises a screen between said sheath and said groups of conductors.
  • the cable further comprises a water blocking filler between said sheath and said groups of conductors.
  • the copper conductors are insulated with material amongst: foam, foam-skin or skin-foam-skin polyolefin (e.g. polyethylene or polypropylene).
  • foam foam-skin or skin-foam-skin polyolefin (e.g. polyethylene or polypropylene).
  • the sheath is made of material amongst: PVC, PE, Low Smoke Zero Halogen compound.
  • the screen is made of material amongst: Al, Al + PET.
  • each group is individually screened.
  • Another object of the invention is a method for specifying an xDSL cable comprising the steps of:
  • the method further comprises a step of selecting a minimum value for the ratio of the diameter of insulation to the diameter of a copper conductor.
  • a telephone cable 1 typically comprises a plurality of conductors 2, generally made of copper. Each conductor 2 is individually insulated by a surrounding insulation 3 shown in zoomed detail on figure 2. Insulated conductors 2 are assembled in groups 4. Each group 4 is individually stranded. A plurality of groups 4 is gathered in bundles or concentric layers to form a cable 1. Individual bundles may be screened or unscreened. A cable 1 may comprise an important number of conductors 2, up to 64 individual conductors or even more. That plurality is inserted in a sheath 5 which protects said conductors 2.
  • cables 1 according to the invention are intended to progressively replace existing telephone network cables. Such existing cables together with all the surrounding network or maintenance equipments are designed with copper diameters of 0.4 or 0.5 mm. For these both reasons, economics and habits, the cable 1 of the invention must preferably stay in the same range.
  • the main idea of the invention is that the crosstalk is both a costly feature to implement (very slow manufacturing speeds) and an inefficient way to increase performance. Much higher gains in bit rate have been demonstrated (theoretically and experimentally) by reducing the cable's attenuation. This is achieved by increasing the cable's impedance, which is a counterintuitive solution for data cables, since return loss is increased, echo generated, and impedance mismatch loss encountered.
  • xDSL systems are extremely tolerant to return loss and echo, since they do not in general use the same band to transmit in both directions. Besides, high losses effectively mask the echoes and return losses generated deep in the network (i.e. far from the modems).
  • Impedance mismatch loss is not a problem for xDSL systems because of the long cable lengths: in other words, the reduction in transmission loss does much more than compensate the mismatch loss. In data cables, typically limited to 100 meters in length, this is not the case.
  • the operational attenuation a b including the reflection losses can be expressed vs.
  • the interaction loss w tends to 1, i.e. 0dB.
  • PSACR is defined as a ratio of attenuation to crosstalk (ACR). This ACR is measured using power sum (PS) to obtain PSACR.
  • PS power sum
  • the PSACR measurement is described in normative document IEC 61156-1 Ed. 1.2 and in Ed. 3.0 in the committee draft 46C/757/CD at section 3.11.
  • the PSACR of each pair in the cable is measured [in dB] at a frequency of 1 MHz and for a cable length of 1 km.
  • a quad is considered as comprising two pairs.
  • the PSACR is only specified at 1MHz it is measured over a frequency range of 100KHz to 10MHz. This is done to be able to draw an envelope over the measured curve and to take the value from this envelope. This is necessary because the PSACR, respectively the PSNEXT measure, is length and frequency dependent showing minimum and maximum values which will change when changing the measurement length.
  • the twist lay length is another parameter affecting performance.
  • the twist lay length is an average measure of the period of the twist of conductors 2 in groups 4. A more stranded group 4, which means a smaller twist lay length, leads to a better performance. Nonetheless, under a certain value of the lay length the cost of the twisting operation becomes too expensive.
  • the invention allows the resulting performance to be obtained with a constant twist lay length of 20 mm or more.
  • a group 4 of stranded conductors 2 may be a quad comprising four conductors 2. It may also be a pair comprising two conductors 2.
  • Another parameter related to performance is a ratio of the diameter of insulation 3 to the diameter of a copper conductor 2 so insulated.
  • the performance increases when the relative amount of insulation 3 increases.
  • the performance can not be increased too much in this way, since the whole diameter of the cable and the price will also tend to increase in an unaffordable manner.
  • the invention allows the resulting performance to be obtained with such a minimum copper to insulation ratio of 1.8 for quad grouped conductors and of 1.9 for paired grouped conductors.
  • the cable 1 may further comprise a screen 7 between said groups 4 of conductors 2 and said sheath 5.
  • the cable 1 may also comprise a water blocking filler 6 between said sheath 5 and said stranded groups 4 of conductors 2.
  • the material for insulation 3 of conductors can typically be chosen amongst foam, foam-skin or skin-foam-skin polyolefin (e.g. polyethylene and polypropylene).
  • foam-skin polyethylene e.g. polyethylene and polypropylene.
  • solid polyethylene e.g. polyethylene and polypropylene.
  • foam-skin polyethylene is the product HE1344 from Borealis.
  • the material of the sheath 5 can typically be chosen amongst Poly Vinyl Chloride (PVC), polyethylene (PE), either with or without laminated aluminium glued and Low Smoke Zero Halogen compound (LSZH), like i.e. SCAPA S500 or POLYONE ECCOH 5860).
  • PVC Poly Vinyl Chloride
  • PE polyethylene
  • LSZH Low Smoke Zero Halogen compound
  • the screen 7 is typically made from a tape of metal, e.g. aluminium (Al), for outdoor applications.
  • the typical thickness of the metal tape in this case is about 0.15 to 0.2 mm.
  • the screen 7 is typically a sandwich tape made of a combination of metal and plastic, e.g. aluminium (Al) and polyester (PET).
  • the typical thickness of the sandwich tape in this case is about 0.05 mm.
  • xDSL cable may comprise an important number of groups 4.
  • some of theses groups 4 may be assembled together in bundles. These bundles may be screened. For high pair counts (e.g. 128 pairs) several of those pairs or quads are assembled together in bundles (e.g. 4 bundles of 32 pairs). The pairs of those bundles may be assembled in concentric layers (e.g. 5+11+16) or in sub bundles (e.g. 4 bundles of 8 pairs). Each of these bundles or sub bundles may or may not be screened.
  • Figure 7, 8 illustrates such assemblies in bundles respectively for a 32 pairs cable and a 128 pairs cable.
  • each group 4 being individually screened.
  • a method of cable specification may be proceeded by the following steps: for a minimum necessary bit rate a minimum PSACR is associated.
  • This minimum PSACR is known from testing of the xDSL performance in a real copper cable infrastructure.
  • For this necessary minimum PSACR a minimum copper diameter of conductors 2 and a minimum twist lay length is chosen. The so obtained PSACR performance will guarantee the associated performance in bit rate.
  • a maximum value for the ratio of the diameter of a copper conductor 2 to the diameter of insulation 3 may be given before proceeding to the step of specifying a maximum twist lay length.
  • the smallest copper diameter possible is chosen to provide the minimum PSACR.
  • Table of figure 4 shows indoor paired unfilled cables. Two prior art cables appear in first to second columns. A cable according to the invention appears on the third and last column.
  • Table of figure 5 shows outdoor quaded filled cables. Three prior art cables appear in first to third columns. A cable according to the invention appears on the last column.
  • figure 6 shows bit rate (vertical axis in Mbit/s) vs. length of cable (horizontal axis in km) comparative performance curves.
  • the lower curve corresponds to a prior art cable and the upper curve corresponds to an improved cable according to the invention.

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  • Communication Cables (AREA)
EP20070300943 2006-04-19 2007-04-12 Câble XDSL Withdrawn EP1848008A2 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP20070300943 EP1848008A2 (fr) 2006-04-19 2007-04-12 Câble XDSL

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP06300377A EP1848007A1 (fr) 2006-04-19 2006-04-19 Câble XDSL
EP20070300943 EP1848008A2 (fr) 2006-04-19 2007-04-12 Câble XDSL

Publications (1)

Publication Number Publication Date
EP1848008A2 true EP1848008A2 (fr) 2007-10-24

Family

ID=38520851

Family Applications (1)

Application Number Title Priority Date Filing Date
EP20070300943 Withdrawn EP1848008A2 (fr) 2006-04-19 2007-04-12 Câble XDSL

Country Status (1)

Country Link
EP (1) EP1848008A2 (fr)

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