1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU42!.3-)33)/.G0G0-%$)!G0G0#(!2!#4%2)34)#3#(!2!#4%2)34)#3G0G0/&G0G039-%42)#G0G00!)234!2G1315!$G0G0#!“,%3G0G0$%3).%$G0G0%!2,)%2&/2G0G0!.!,/5%G0G042!.3-)33)/.G0G03934%-3!.$G0G0“%).G0G053%$G0G0./7G0G0&/2G0G0$)4!,393
2、4%-G0G042!.3-)33)/.G0G0!4G0G0“)4G0G02!4%3/&G0 G0G04/G0G0 G0-BIT S)45G134G0G0RecommendationG0G0 (Extract from the “LUEG0“OOK)NOTES1 ITU-T Recommendation G.614 was published in Fascicle III.3 of the Blue Book. This file is an extract fromthe Blue Book. While the presentation and layout of the text mig
3、ht be slightly different from the Blue Book version, thecontents of the file are identical to the Blue Book version and copyright conditions remain unchanged (see below).2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both atelecommunication administrati
4、on and a recognized operating agency. ITU 1988, 1993All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic ormechanical, including photocopying and microfilm, without permission in writing from the ITU.Fascicle III.3 - Rec. G.614 1Recom
5、mendation G.614Fascicle III.3 - Rec. G.614CHARACTERISTICS OF SYMMETRIC PAIR STAR-QUAD CABLESDESIGNED EARLIER FOR ANALOGUE TRANSMISSION SYSTEMSAND BEING USED NOW FOR DIGITAL SYSTEM TRANSMISSIONAT BIT RATES OF 6 TO 34 Mbit/s(Melbourne, 1988)1 IntroductionThis Recommendation relates to symmetric pair s
6、tar-quad cables which have been designed earlier and used toprovide 60 or 120 carrier telephone channels of analogue transmission systems on each quad pair. Further, afterreconstruction of the line, these cables are used for digital system transmission at bit rates of 6 to 34 Mbit/s. The cablesconce
7、rned have no screened pairs and quads.For digital transmission systems with a bit rate of 8 Mbit/s both one-cable and two-cable operations may beused. For systems with a bit rate of 34 Mbit/s two-cable operation is used only.For digital transmission systems both several, or all cable pairs may be us
8、ed.2 Parameters to be measuredAll parameters specified in Recommendation G.612, namely characteristic impedance, attenuation coefficient,far-end crosstalk between pairs on the same direction of transmission, and near-end crosstalk between pairs of twodifferent cables intended for different direction
9、s of transmission are to be measured. If the cable is intended for use withboth directions of transmission it is also necessary to measure the near-end crosstalk between pairs intended for differentdirections of transmission.2.1 Characteristics impedanceThe characteristics impedance is measured acco
10、rding to 2.1 of Recommendation G.612.2.2 Attenuation coefficientThe attenuation coefficient is measured according to 2.2 of Recommendation G.612.2.3 CrosstalkThe crosstalk is specified in sinusoidal mode at a frequency near the timing half-frequency of the digital systemand/or at other frequencies.
11、Digital mode of measuring may be used also.2.3.1 Measurement of far-end crosstalk between pairs of different quadsThe measurement of the far-end crosstalk is carried out on pairs used in the same direction of transmission at afrequency above about 0.1 MHz when a length of cable is L. If the frequenc
12、y of measurements differs from the timinghalf-frequency of the digital transmission system the value to be measured will be corrected to the factor 20 log10f . Thevalues are corrected to the length of 1000 m by the factor 10 log10L.2.3.2 Measurement of far-end crosstalk between pairs of the same qua
13、dThis measurement is carried out at a cable length equal to maximum permissible length of regenerator section ofdigital transmission system with bit rates of 6 to 34 Mbit/s at a frequency above about 1.0 MHz (measurement is carriedout for each rate of digital transmission system separately) with sys
14、tematic component of crosstalk in the same quadcompensated. The compensation of systematic crosstalk component is carried out by one of the approximately equivalenttransposition patterns (see Figure 1/G.614). When regenerator sections are of less length these methods of falling theelementary cable s
15、ections into separate parts and of transposition in quad provide the greater values of the far-endcrosstalk between pairs than those values when measurements are carried out at, a maximum length of regeneratorsection.2 Fascicle III.3 - Rec. G.614Note 1 - Transposition pattern No. 1 was proposed by t
16、he Netherlands Administration in 1978 (seeCOM XV-135, period 1977-1980).Note 2 - Transposition pattern No. 2 has been proposed by the German Democratic RepublicAdministration.Note 3 - Transposition patterns Nos. 3, 4, 5 and 6 are proposed by the USSR Administration.FIGURE 1/G.6142.3.3 Measurement of
17、 near-end crosstalk between pairs of the same or different cables intended for differentdirections of transmissionThis measurement is carried out either between pairs of the same cable (when one-cable operation is used), orbetween pairs of two different cables intended for different directions of tr
18、ansmission (when two-cable operation isused). The measurements are carried out both in sinusoidal and digital modes.3 Cable specificationAdministrations which decided to use cables designed earlier and used for analogue carrier systems with up to120 channels in digital operation at bit rates 6 to 34
19、 Mbit/s are recommended to choose cables with characteristics givenin Tables 1/G.614 and 2/G.614.Fascicle III.3 - Rec. G.614 33.1 Tables used for digital transmission systems with bit rates of 6 to 8 Mbit/s in one-cable operationSee Table 1/G.614.TABLE 1/G.614Characteristics RequirementsTypes of cab
20、le I(Note 1)II(Note 1)III(Note 1)Operational bit rate C, kbit/sLine codeModulation rate, kbaudTolerate attenuation of regenerator section at a frequency of C/2 whenpairs of cable are of maximum use and directions of transmission are setin different quads (maximum permissible value), dBDiameter of co
21、pper conductor, mmPrevious cable operating rangeType of insulationNumber of star quadsCharacteristic impedance at 1 MHz, ohmsNominal capacity, nF/kmAttenuation coefficient, dB/km at 10C- at 1 MHz-at a frequency C/2Near-end crosstalk at a frequency of C/2, dB-mean value-minimum valueFar-end crosstalk
22、 between pairs of different quads(minimum value referred to 1,000 m), dB- at 1 MHz- at a frequency of C/2Far-end crosstalk between pairs of the same quad (minimum value atregenerator section of maximum length), dB- at 1 MHz- at a frequency of C/28448HDB-38448231.2HFP1416524.54.810.64834544260438448H
23、DB-38448231.2HFP17(Note 2)16524.54.59.75034544260438448HDB-3844845(Note 3)1.3AF, HFP1, P3, 4, 817021.03.78.0504460486048Note 1 - These characteristics relate to cables with aluminium covering.Note 2 - Central quad not used for digital system transmission.Note 3 - Regenerators of the transmission dir
24、ection B-A installed in midpoint of the section of the opposite direction A-B.HF High-frequencyAF Audio-frequencyPl String polystereneP Paper4 Fascicle III.3 - Rec. G.6143.2 Cables used for digital transmission systems with bit rates of 6 to 34.368 Mbit/s in two-cable operationSee Table 2/G.614.TABL
25、E 2/G.614Characteristics RequirementsType of cable I(Note 1)II(Note 1)III(Note 1)Operational bit rate C, kbit/sLine codeModulation rate, kbaudAttenuation of regenerator section at a frequency of C/2 when all pairsof cable are used (maximum permissible value), dBDiameter of copper conductor, mmNumber
26、 of star quadsCharacteristic impedance at 1 MHz, ohmsNominal capacity, nF/kmAttenuation coefficient, dB/km at 10C- at 1 MHz- at a frequency C/2Far-end crosstalk between pair ofdifferent quads (minimum value referred to 1,000m), dB- at 1 MHz- at 4 MHz- at 12 MHz- at 17 MHzFar-end crosstalk between pa
27、irs of the same quad (minimum value at aregenerator section of maximum length), dB- at 1 MHz- at 4 MHz- at 12 MHz- at 17 MHz8448HDB-38448701.2416524.54.810.65442-4230-34 3685B6B41 242851.2416524.54.824.051423230-33(Note 2)17(Note 2)13(Note 2)34 3685B6B41 242851.33, 4, 817021.03.717.06048302660(Note
28、3)48(Note 3)27(Note 3)17(Note 3)Note 1 - These characteristics relate to cables with aluminium covering.Note 2 - These values are obtained by means of transposition pattern No. 5 (see Figure 1/G.614) for four cable lengths (0.825 km).Note 3 - These values are obtained by means of transposition pattern No. 2 (see Figure 1/G.614).
