1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 - TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU-!).4%.!.#% ).4%2.!4)/.!,G0G04%,%0(/.%G0G0#)2#5)43-!).4%.!.#%G0G0-%4(/$3)45G134G0G02ECOMMENDATIONG0G0- (Extract from the “LUEG0“OOK)NOTES1 ITU-T Recommendation M.730 was published in Fascicle IV.1 of the Blue
2、 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 conditions remain unchanged (see below).2 In this Recommendation, the e
3、xpression “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 form or by any means, electronic ormechanical, including photoc
4、opying and microfilm, without permission in writing from the ITU.Fascicle IV.1 - Rec. M.730 1Recommendation M.730Fascicle IV.1 - Rec. M.730MAINTENANCE METHODS1 GeneralIn order to meet the service demands of a progressive and rapidly expanding international fully automatictelephone network with the b
5、est possible quality of service, it is essential that all factors adversely affecting the qualityof service should be detected and service restored as quickly as possible. In setting this objective it is recognized thatperfect performance is unattainable and that beyond a certain point, costs can ri
6、se sharply out of proportion comparedwith service quality gain.When choosing a suitable maintenance method or a combination of methods one should consider: the reliability of the plant to be maintained; the availability of testing and supervisory facilities as well as the availability and quality of
7、 manpower inthe maintenance organization; the availability of facilities in the plant that indicate the existence and frequency of disturbances; the availability of arrangements for automatic remedial action; the availability of automatic means to process and analyse operational data received from t
8、he plant; the final objective i.e. to ensure a satisfactory overall service quality (subscriber-to-subscriber) in theinternational connection, giving equal importance to the national and international parts of the chain thatconstitute the connection.It is recognized that a combination of maintenance
9、 methods may be applied.2 Preventive maintenance methods2.1 GeneralThe introduction of stored program control (SPC) exchanges and digital transmission systems reduce the needfor preventive maintenance. SPC exchanges should in general be provided with functions which supervise the signalling,switchin
10、g and transmission processes. If a fault occurs or if pre-set disturbance limits are reached, data which indicatethe concerned device(s) or circuit(s) should be printed out.External supervision, testing and fault localization functions should be avoided if internal functions in SPCexchanges or digit
11、al transmission systems can provide the same facilities.2.2 Functional tests2.2.1 In carrying out functional tests, ordinary working conditions apply and the equipment and circuits are taken asfound.They are carried out on a systematic basis to discover faults that would influence the quality of ser
12、vice. Theresponse to each signal may be tested by equipment provided for this purpose. Such tests may be applied to any part ofthe signalling path.2.2.2 Functional tests are carried out locally, or from either end of an international circuit to the other.2.2.3 The organization of the programme for c
13、arrying out functional tests locally is left to the discretion of theAdministration responsible for the international exchange.2.2.4 Overall functional tests on an international circuit are such that they can be made from one end of the circuitwithout cooperation of technical personnel at the other
14、end of the circuit. These tests may utilize the switchingequipment at each end of the circuit, but such equipment is not being tested directly, only the circuit.The verification of satisfactory signalling operation may be done by using various types of tests: Certain types of tests not requiring any
15、 special equipment, for example checking that a seizing signal isfollowed by the return of a proceed-to-send signal and that a clear-forward signal is followed by thereturn of a release-guard signal.2 Fascicle IV.1 - Rec. M.730 Other types combining several tests, using special equipment at both end
16、s. Any type which is in generaluse by Administrations may be used if suitable and agreed between the Administrations concerned1).2.3 Circuit limit tests2.3.1 A circuit limit test is made to verify that the international circuit meets specified operating margins. These testsenable the performance of
17、the whole international circuit to be checked. They will be made as required but normally atthe following times: before putting the circuit into service; according to a systematic test programme which may be based on measurement results or fault (trouble)statistics or quality of service observations
18、 (see Recommendation M.605).They may also be made if functional tests indicate a fault, in order to locate such a fault.Circuit limit tests may be made with respect either to transmission or to signalling conditions.2.3.2 The frequency of such tests will be determined by the Administrations concerne
19、d and the test conditions to beapplied will be in conformity with CCITT Recommendations.2.3.3 The test equipment, the specifications and methods of gaining access to this equipment are described in thespecifications of international signalling, switching and transmission equipment.2.4 Limit tests on
20、 the constituent parts of a circuit2.4.1 These limit tests are made to verify that the constituent parts of a circuit meet specified operating margins.They will be made as required but normally at the following times: at installation; if functional or limit tests on the circuit indicate a fault, if
21、such tests will help in fault location; systematic test programmes which may be based on measurement results or trouble statistics or quality ofservice observations.2.4.2 The frequency of such tests will be determined by the Administrations concerned and the test conditions to beapplied will be in c
22、onformity with CCITT Recommendations.2.4.3 Limit tests on constituent parts may indicate that the latter need to be readjusted; in such a case, measurementsare made on those constituent parts and they are then readjusted in accordance with the relevant CCITTRecommendations.2.4.4 The test equipment,
23、its specification and the provision of access points will be determined by theAdministration concerned taking into account the relevant CCITT Recommendations.2.5 Maintenance measurements2.5.1 GeneralMaintenance measurements are made periodically on complete circuits (and exceptionally, are indicated
24、 inRecommendation M.610 on their constituent parts). Their object is to indicate whether the circuits and equipments aremaintained to their specified values when first put into service and, if not, to allow the necessary readjustment to becarried out.Some maintenance measurements are made to check s
25、ignalling; others are made to check transmission. Theyare carried out by the respective technical services responsible for signalling and transmission.2.5.2 Measurements concerning signallingThe conditions for carrying out such measurements, the apparatus used and the periodicity of operations arede
26、termined by the relevant Series Q Recommendations. Interventions following such measurements are determined by:a) CCITT Recommendations;b) equipment specifications when these are not given in detail by the CCITT._1)See the specification for the CCITT Automatic Transmission Measuring and Signalling T
27、esting Equipment ATME No. 2(Recommendation O.22 1).Fascicle IV.1 - Rec. M.730 3Information on the equipment and functions required are given in the Recommendations listed inTable 1/M.730.TABLE 1/M.7302.5.3 Measurements concerning transmissionThese measurements include: local measurements, for which
28、the Administrations concerned decide the conditions and periodicity; circuit and line measurements for which the conditions are generally defined in the Series MRecommendations.These Series M Recommendations give, in particular, the periodicity of the measurements and the conditionsfor readjustment
29、of transmission equipment. (See also Recommendation M.733.)The CCITT has already specified certain transmission measuring apparatus, and other apparatus specificationsare being studied.3 Corrective maintenance methodsThese methods may apply to certain parts of the plant where it is possible to locat
30、e and clear faults solely afterthey have affected the service. Corrective maintenance, if exclusively practised in the entire plant, can createunsatisfactory service conditions due to extreme variations in functional quality and can cause very irregular applicationof maintenance effort.The applicati
31、on of exclusively corrective maintenance methods would presuppose such system design thateven if breakdowns of single units or parts of the plant occur, they should have a minor effect on the service qualityoffered to the subscribers.4 Controlled maintenance methodsWhereas it has been the practice t
32、o undertake programmes of preventive maintenance procedures together withday-to-day corrective maintenance procedures, recent equipment development has made it possible to introduce newmaintenance methods. Modern systems can provide immediate information concerning the existence of irregularities an
33、dof abnormal conditions. Although preventive maintenance gives a comparatively good service, the number of defectscaused by interference of preventive operations may be considerable.A maintenance method utilizing the supervising facilities now available may enable the maintenanceorganization to cons
34、iderably reduce preventive routines in the maintenance work. Preventive routine tests may then bereplaced by methods of continuous supervision of the function of the plant and by means which check continuously theperformance of the equipment and give signals to the maintenance staff when the quality
35、 of service is below a presetacceptance limit. Alternatively, when facilities for continuous supervision are not available, a sampling technique couldbe introduced to determine the number of routine tests necessary to gain a reasonable assurance that all equipments arein proper order.Signalling Syst
36、em RecommendationNo. 4 Q.138 2No. 5 Q.164 3No. 6 Q.295 4R2 Q.490 5No. 7 Q.707 64 Fascicle IV.1 - Rec. M.730Introduction of a system of maintenance control of this kind will necessitate a certain degree of centralizationof administrative and technical means in the maintenance organization. Rapid and
37、informative indication of the state andperformance of the international and concerned parts of the national network is required from the maintenance point ofview at strategic points in the network.Various types of information on operational conditions in the plant can be utilized for maintenance sup
38、ervisionpurposes, such as: traffic data; accounting data; maintenance data; service performance data.Such data may be analysed manually but could also be processed in computers, allowing for a more extensiveanalysis, for instance, to compare performance statistics with preset standards which are set
39、 for particular routes,circuits, etc. Information held in the computer store may be extracted on-line and could be made directly available tothose maintenance and management centres where it is required.Application of computer processing as described necessitates a high degree of centralization, but
40、 also otherfactors support a centralized maintenance organization such as the increasing use of network management signals. Theintroduction of processor-controlled switching and digital transmission systems is also expected to increase thepossibilities to apply remote controlled and centralized main
41、tenance supervision methods in the future.References1 CCITT Recommendation CCITT automatic transmission measuring and signalling testing equipmentATME No. 2, Vol. IV, Rec. O.22.2 CCITT Recommendation Instruments for checking equipment and measuring signals, Vol. VI, Rec. Q.138.3 CCITT Recommendation
42、 Test equipment for checking equipment and signals, Vol. VI, Rec. Q.164.4 CCITT Recommendation Testing and maintenance Overall tests of Signalling System No. 6, Vol. VI,Rec. Q.295.5 CCITT Recommendation Testing and maintenance, Vol. VI, Rec. Q.490.6 CCITT Recommendation Testing and maintenance, Vol. VI, Rec. Q.707.
