1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 - TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU-!).4%.!.#%G0 ).4%2.!4)/.!,G0G042!.3-)33)/.G0G03934%-3!.!,/5%G9“2).).G0G0!G0G0.%7G0G0).4%2.!4)/.!,42!.3-)33)/.G0G03934%-G0G0).4/3%26)#%)45G134G0G0RecommendationG0G0- (Extract from the “LUEG0“OOK)NOTES1 ITU-T
2、Recommendation M.450 was published in Fascicle IV.1 of the Blue Book. This file is an extract fromthe Blue Book. While the presentation and layout of the text might be slightly different from the Blue Book version, thecontents of the file are identical to the Blue Book version and copyright conditio
3、ns remain unchanged (see below).2 In this Recommendation, the expression “Administration” is used for conciseness to indicate both atelecommunication administration and a recognized operating agency. ITU 1988, 1993All rights reserved. No part of this publication may be reproduced or utilized in any
4、form or by any means, electronic ormechanical, including photocopying and microfilm, without permission in writing from the ITU.Fascicle IV.1 - Rec. M.450 1Recommendation M.450Fascicle IV.1 - Rec. M.450BRINGING A NEW INTERNATIONAL TRANSMISSIONSYSTEM INTO SERVICE1 Preliminary exchange of informationA
5、s soon as Administrations have decided to bring a new international transmission system into service, thenecessary contacts are made between their technical services1)for the exchange of information. Those services jointlyselect the control and sub-control stations for the new system (see Recommenda
6、tions M.80 and M.90).The technical service of each Administration is responsible for the setting-up and lining-up of the line sectionson its territory and for arranging that the adjustments and tests required are made by the repeater station staff concerned.To set up a line section which crosses a f
7、rontier, Administrations should arrive at bilateral arrangements on thebasis of CCITT Recommendations and, for radio-relay sections, the Recommendations of the CCIR.2 Setting up sections crossing a frontier2.1 Radio-relay sectionDetails of the following points will have been settled by a bilateral a
8、greement between the technical services ofAdministrations: geographical position of the radio-relay station nearest to the frontier; contour of the terrain of the radio section crossing the frontier, with details of the height of the antennaeabove normal level; directivity characteristic and gain of
9、 the antennae; radio-frequency channel arrangement (centre frequency, polarization, intermediate frequency); provision of supervisory system; radio equipment line-regulating pilots (if any); continuity pilots, used for supervising the radio-relay link, in accordance with theCCIR Recommendations on t
10、he frequency and frequency deviation of this signal, each countrytransmitting the pilot required by the system in the receiving country; noise measurement channels outside the transmitted baseband; total noise for the radio-relay section; frequency deviation of the telephony channel the level of whi
11、ch at the centre frequency is unaffected bypre-emphasis (either of the telephony channel itself or of the radio-frequency channel of the system); pre-emphasis characteristics of the radio-frequency channel; service, supervisory and remote channel circuits; level, frequency and coding of the signals
12、transmitted over these lines; protective switching equipment; interconnection points T, R, T, R (see Figure 1/M.450) defined in Recommendation G.213 1 (seealso 2 and especially the return loss at points R and R if required (see CCIR Recommendation 380 3for values)._1)The technical service represents
13、 the appropriate authorities within the international maintenance organization of an Administrationwhich have the responsibility for making international agreements on engineering provision and maintenance matters, specifyingprovision and maintenance facilities, determining engineering and maintenan
14、ce policy and overseeing its implementation.2 Fascicle IV.1 - Rec. M.450FIGURE 1/M.450Interconnection points T, R, T , Rd01-scw2.2 Coaxial-pair line sectionDetails of the following points will have been settled by bilateral agreement between the technical services ofthe Administrations: the choice o
15、f the frequency arrangement to be adopted; the pilot signals to be used for regulating the line, in accordance with CCITT Recommendations on thefrequency and level of such signals, each country transmitting the pilot signals required by the equipmentof the other country (see the table in Recommendat
16、ion M.540 indicating the pilot frequencies for varioussystems); service, supervisory and remote control circuits; repeater identification method and frequencies for fault location and monitoring on transistorized systems; provisions for remote power feeding, where a section of the supply line crosse
17、s the frontier; the regulation systems used by each country; the nominal level at various frequencies, at the output of the frontier repeater.Concerning this last item, at the incoming point, each Administration should as far as possible accept theconditions usual for the system of the other country
18、.During the lining-up tests, the relative power level measured at the output of the repeater in the unburiedrepeater station nearest to the frontier should not differ, for any frequency, by more than 2 dB from the nominal value(as defined by a graph drawn up beforehand and based on the characteristi
19、cs of the system in question).The frequencies used in lining up the line are determined by agreement between the Administrationsconcerned. Experience shows that, provided the number of test frequencies required is not too large, it is useful to makethese tests at frequencies lying very close to each
20、 other at the edges of the frequency band, or at points whereirregularities have to be corrected, and at frequencies less close to each other elsewhere in the band.If the necessary test equipment is available sweep measurements can substantially facilitate the line-upprocedure. But in this case also
21、, some test frequencies have to be agreed upon to obtain reference values for later in-service maintenance measurements.Fascicle IV.1 - Rec. M.450 32.3 Symmetric-pair line sectionThe following points will have been settled by bilateral agreement between the Administrations: frequency allocation; pil
22、ots (see the table in Recommendation M.540 indicating the pilot frequencies for various systems); service, supervisory or remote control lines, etc.; repeater identification method and frequencies for fault location and monitoring on transistorized systems; provisions for remote power feeding, where
23、 a section of the supply line crosses the frontier.When a symmetric-pair line section crossing a frontier section is first set up, tests should be made at clearlydefined frequencies to determine the insertion loss/frequency characteristics. For example, frequencies spaced at thefollowing intervals c
24、ould be used, except at the edges of the band, where more closely spaced measuring frequencies aredesirable.4 kHz between 12 kHz and 60 kHz,8 kHz between 60 kHz and 108 kHz,12 kHz between 108 kHz and 252 kHz,24 kHz between 288 kHz and 552 kHz.The conditions for making measurements at line-pilot freq
25、uencies should be agreed by the technical serviceconcerned.Level measurements at the frequencies chosen will be made at each line amplifier at the unburied repeaterstation nearest to the frontier. The relative power level measured at any of the frequencies chosen should not differ bymore than 2.0 dB
26、 from the nominal value.3 Overall reference measurements for the lineThe section across frontiers and national sections having been set up and connected, reference measurementsare made between the high-frequency line terminals of the carrier system, excluding the terminal equipment.3.1 Level measure
27、mentsThese are made at several frequencies, even if the regulated line section or line link has been equalized bymeans of sweep frequency measurements.3.1.1 Radio-relay line sectionWhen a radio-relay section is put into service, measurements and adjustments in accordance with the CCIRRecommendations
28、 for the radio-relay system concerned are first made of: the frequency at which the level is unchanged by pre-emphasis and the deviation of that frequency; the level and frequency of the baseband reference frequency; the central position of the intermediate frequency (if necessary); check and adjust
29、ment of input and output levels baseband/baseband (see CCIR Recommendation 380 3for values); measure of overall loss/frequency characteristics using additional measurement frequencies2).3.1.2 Coaxial line sectionThe frequencies for reference measurements should be selected from the following values.
30、 (These valuescomprise the line pilot frequencies which, of course, cannot be sent into a system with the pilots already beingtransmitted.)_2)Reference measurements should be made at several frequencies in both directions of transmission between accessible measuringpoints corresponding as nearly as
31、possible to points R and R as defined in Recommendation G.213 1. These measurementsshould be made at the frequencies specified in 3.1.2 for each transmitted bandwidth.4 Fascicle IV.1 - Rec. M.4503.1.2.1 For a 1.3-MHz system: 60, 308, 556, 808, 1056, 1304, 1364 kHz.3.1.2.2 For a 2.6-MHz system: 60, 3
32、08, 556, 808, 1056, 1304, 1552, 1800, 2048, 2296, 2604 kHz.3.1.2.3 For a 4-MHz system: frequency allocation with supergroups:60, 308, 556, 808, 1056, 1304, 1552, 1800, 2048, 2296, 2544, 2792, 3040, 3288, 3536, 3784, 4092,4287 kHz; frequency allocation with mastergroups (Figure 5/M.380, scheme 2):308
33、, 560, 808, 1304, 1592, 2912, 4287 kHz.3.1.2.4 For a 6-MHz system: frequency allocation with supergroups:308, 556, 808, 1056, 1304, 1552, 1800, 2048, 2296, 2544, 2792, 3040, 3288, 3536, 3784, 4287,(5680)3)kHz; frequency allocation with mastergroups (Figure 8/M.380, scheme 3):308, 560, 808, 1304, 159
34、2, 2912, 4287, 56083)kHz.3.1.2.5 For a 12-MHz system: at frequencies below 4 MHz:if frequency allocation without mastergroups is used:308, 560, 808, 1056, 1304, 1552, 1800, 2048, 2296, 2544, 2792, 3040, 3288, 3536 and 3784 kHz(the frequencies in italics are those at which the measurements must alway
35、s be made);if frequency allocation with mastergroups is used:308, 560, 808, 1304, 1592 and 2912 kHz; at frequencies above 4 MHz:if frequency allocation with 15 supergroup assemblies is used:5392, 7128, 8248, 8472, 8864, 9608 and 11 344 kHz;if frequency allocation with mastergroups is used:5608, 6928
36、, 82484), 8472, 9792 and 11 112 kHz.3.1.2.6 For an 18-MHz system: if frequency allocation is according to Plan 1 of Recommendation G.334 4:560, 808, 1304, 1592, 2912, 5608, 6928, 82484), 8472, 9792, 11 112, 12 678 or 12 760, 14 408, 15 728and 17 242 kHz; if frequency allocation is according to Plan
37、2 of Recommendation G.334 4:560, 808, 1056, 1304, 1552, 1800, 2048, 2296, 2544, 2792, 3040, 3288, 3536, 3784, 5392, 7128, 8248,8472, 8864, 9608, 11 344, 12 678 or 12 760, 14 408, 15 728 and 17 242 kHz (the frequencies in italicsare those at which measurements must always be made); if frequency alloc
38、ation is according to Plan 3 of Recommendation G.334 4:552, 1872, 3192, 4758, 6272, 7592, 9158, 10 672, 11 992, 1 3 558, 15 072 and 16 392 kHz5).3.1.2.7 For a 60-MHz system: frequencies which do not cause interference to a regulated line section and, therefore, can be sent at anytime:8472, 12 678 or
39、 12 7606), 17 488, 26 922, 31 322, 35 722, 40 1226), 42 322, 46 722, 51 122, 55 522 kHz; frequencies which should not be sent without the agreement of the Administration at the receiving end:42007)or 42878), 83167), 12 4358), 22 302, 22 3728), 40 9208), 59 992 kHz._3)This frequency may be 5640 kHz.4
40、)A frequency of 8248 kHz can be used as a radio-relay link line regulating pilot. In such a case, the precautions shown inRecommendation G.423 5 should be applied.5)These measuring frequencies are provisional and subject to further study by Study Group XV.6)It may be necessary to use this frequency
41、if an adjacent auxiliary line pilot is used for regulation.7)These frequencies may also be in use as frequency comparison pilots.Fascicle IV.1 - Rec. M.450 53.1.3 Symmetric-pair line sectionFrequency of the line pilot or pilots, and frequencies showing the insertion loss/frequency characteristic of
42、theline, for example, frequencies spaced at:4 kHz between 12 kHz and 60 kHz,8 kHz between 60 kHz and 108 kHz,12 kHz between 108 kHz and 252 kHz,24 kHz between 288 kHz and 552 kHz.3.2 Loss/frequency distortionThe loss/frequency distortion of the regulated line section (symmetric pair, coaxial or radi
43、o-relay link) shall besuch that the relative level at any frequency does not differ by more than 2 dB from the nominal level for older type-systems and 1 dB in case of modern transistorized systems.Reference measurements at the frequencies chosen will be made at all attended stations at the output o
44、f eachamplifier and also at the unburied station nearest the frontier.Reference tests at unattended stations other than frontier stations are left to the discretion of eachAdministration.The setting of equalizers should be noted and recorded during the reference measurements as well as thetemperatur
45、e of the cable, or the resistance of one of the conductors, from which the temperature could be deduced.3.3 Measurement of noise powerMeasurements of noise power shall be made by sending a uniform continuous spectrum signal in thetransmitted frequency band in accordance with Recommendations G.228 6
46、and G.371 7 and CCIRRecommendation 399 89).3.4 Complementary measurementsIf the Administrations find it necessary, the following measurements could also be made: check of near-end crosstalk with artificial loading of radio channels; check of the suppression of line pilots from other regulated sectio
47、ns; check of power supply modulation, etc. (including checking of the baseband for the presence ofinterfering signals from radio-frequency sources outside the system); check of stability using a level recorder.3.5 Line-up recordThe results of the reference measurements made at the line terminals and
48、 at the output of frontier repeaters willbe entered in a line-up record, specimens of which are included as examples in Appendices I (coaxial or radio-relayregulated line section line-up record) and II (symmetric-pair regulated line section line-up record) below.8)In accordance with Recommendation M
49、.500, Administrations choosing to use these frequencies must ensure that interference isnot caused to a following regulated line section which may be using these frequencies as line pilots.9)In the case of a radio-relay line section, measurements should also be taken outside the baseband on the noise measurementchannels indicated in CCIR Recommendation 398 9. These noise values will serve as reference values for subsequentmaintenance measurements.6 Fascicle
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