ITU-T G.352-1988 不同设计的同轴载波的互连 Interconnection of coaxial carrier systems of different designs

pdf标准 ITU-T G.352-1988 不同设计的同轴载波的互连 Interconnection of coaxial carrier systems of different designs

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ITU-T G.352-1988 不同设计的同轴载波的互连 Interconnection of coaxial carrier systems of different designs  第 1 页 ITU-T G.352-1988 不同设计的同轴载波的互连 Interconnection of coaxial carrier systems of different designs  第 2 页 ITU-T G.352-1988 不同设计的同轴载波的互连 Interconnection of coaxial carrier systems of different designs  第 3 页 ITU-T G.352-1988 不同设计的同轴载波的互连 Interconnection of coaxial carrier systems of different designs  第 4 页 ITU-T G.352-1988 不同设计的同轴载波的互连 Interconnection of coaxial carrier systems of different designs  第 5 页
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国外分类,ITU,ITU-T(电信标准分局),itu,不同,设计,同轴,载波,互连,interconnection,of,coaxial,carrier,systems,of,different,designs

INTERNATIONAL TELECOMMUNICATION UNION )45 4 ' TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU ).4%2.!4)/.!, !.!,/'5% #!22)%2 3934%-3 ).$)6)$5!, #(!2!#4%2)34)#3 /& ).4%2.!4)/.!, #!22)%2 4%,%0(/.% 3934%-3 /. -%4!,,)# ,).%3 ).4%2#/..%#4)/. /& #/!8)!, #!22)%2 3934%-3 /& $)&&%2%.4 $%3)'.3 )45 4 Recommendation ' (Extract from the "LUE "OOK) NOTES 1 ITU-T Recommendation G.352 was published in Fascicle III.2 of the Blue Book. This file is an extract from the Blue Book. While the presentation and layout of the text might be slightly different from the Blue Book version, the contents 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 a telecommunication administration and a recognized operating agency. © ITU 1988, 1993 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the ITU. Recommendation G.352 Fascicle III.2 - Rec. G.352 INTERCONNECTION OF COAXIAL CARRIER SYSTEMS OF DIFFERENT DESIGNS1) (amended at Mar del Plata, 1968 and Geneva, 1980) In every case of interconnection of coaxial carrier systems of different types at frontiers, some special arrangements are required to enable the systems to interwork satisfactorily. The following points require special attention: 1 Pilots Each line-regulating pilot should be transmitted on the two systems to be interconnected, at the same absolute power level (referred to a point of zero relative level). If the two systems do not use the same frequencies for the pilots, each of the stations situated at the ends of the regulated-line section crossing the frontier should be equipped to send all the pilots needed by both systems. 2 Transmission conditions For interconnecting systems using different pre-emphasis values and output levels at national boundaries, Administrations can agree to equalize the level differences by shortening the frontier cable section and adding suitable passive equalizer networks as indicated in Annex A. There may be cases in which even shortening the cable section to zero is not sufficient to equalize completely the level differences. It is recommended in these cases that the residual small level differences be finally corrected in the next main repeater station. In some cases it may be feasible to maintain the normal repeater spacing in the frontier cable section and to accept some level differences at some intermediate repeaters near the frontier, ancillary gain and correcting networks being provided in the nearest main station (see Annex B). 3 Power feeding In the absence of a special agreement between the Administrations concerned in a power-feeding section crossing a frontier, it is recommended that each Administration power-feed only the repeater stations on its own territory. 4 Supervision and alarms In each particular case, these points should be agreed by Administrations concerned. 5 Conditions for the repeater section The CCITT has standardized the dimensions of the coaxial pairs to be used in the international European telephone network (see Recommendations G.622 and G.623). Nevertheless, this standardization allows certain variations, so that the coaxial pairs manufactured by different contractors in different countries may not have exactly the same characteristics. To ensure uniformity throughout the frontier repeater section, it is strongly recommended that, by agreement between the two Administrations concerned the manufacture of the whole section should be entrusted to the same firm. If the same contractor does not supply the whole section, the two Administrations concerned must very carefully coordinate their detailed specifications and their methods of laying and jointing, to ensure that the conditions recommended by the CCITT for the complete elementary cable section are met. _______________ 1) This Recommendation applies to 1.3 MHz, 4 MHz, 6 MHz, 12 MHz, 18 MHz and 60 MHz systems. Fascicle III.2 - Rec. G.352 1 As regards matching of the impedance of this repeater section to the impedances of the two adjacent amplifiers, in the general case of a coaxial cable section between two adjacent repeaters and used for telephony only, the CCITT has defined only the permissible limits for the sum N of the three terms defined in Recommendation G.332, § 5. It is recommended that the Administrations concerned with a coaxial cable section crossing a frontier, agree on the values for each of these three terms permissible to meet the above condition - i.e. agree on the use of as good a match as possible. It is also ver

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