1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 - TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU-!).4%.!.#% ).4%2.!4)/.!,G0G04%,%0(/.%G0G0#)2#5)4342!.3-)33)/.G0G02/54).%G0G0-!).4%.!.#%-%!352%-%.43G0G0/.G0G0!54/-!4)#G0G0!.$3%-)G13!54/-!4)#G0G04%,%0(/.%G0G0#)2#5)43)45G134G0G0RecommendationG0G0- (Extract f
2、rom the “LUEG0“OOK)NOTES1 ITU-T Recommendation M.733 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 Boo
3、k version and copyright conditions 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 b
4、e reproduced or utilized in any form or by any means, electronic ormechanical, including photocopying and microfilm, without permission in writing from the ITU.Fascicle IV.1 - Rec. M.733 1Recommendation M.733Fascicle IV.1 - Rec. M.733TRANSMISSION ROUTINE MAINTENANCE MEASUREMENTSON AUTOMATIC AND SEMI
5、AUTOMATIC TELEPHONE CIRCUITSThe object of routine maintenance measurements is to detect changes in transmission conditions before suchchanges cause a reduction in the quality of service provided. These changes are those which occur relative to the valuesrecorded for maintenance purposes for the cir
6、cuits or link concerned. In the various sections of the Series MRecommendations limits are laid down within which: no readjustment is necessary, readjustment may be made at the terminal stations, readjustment must be made along the whole circuit or link.Routine maintenance measurements should be mad
7、e according to an agreed maintenance schedule (seeRecommendation M.605). The periodicities for the measurements are given in Tables 1/M.610 and 2/M.610. These areto be considered as recommended values and may be increased or reduced if special circumstances require.Routine maintenance measurements m
8、ust normally be made at times of light traffic, where staffingarrangements permit. If such measurements have to be made on a large group of circuits, it may nevertheless benecessary to do the measurements on some of the circuits during the busy period, if the operating services are notadversely affe
9、cted thereby.Circuits on a given route are generally measured in batches based on the way in which the maintenanceschedule has been arranged (see Recommendation M.605). The advantages are: once cooperation has been arranged for routine testing with a distant station, time is saved if testcooperation
10、 can be maintained for as long as necessary; testing a large number of circuits on one route within a fairly short period enables a more accurateoverall notion of the route to be obtained than could be gained from measurements on only a fewcircuits.Routine maintenance measurements should be made on a complete circuit and should include measurementsof overall loss and levels at one and several frequencies, stability (for 2wire audio circuits only), and noise.
