1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 - TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU-!).4%.!.#%G0 ).42/$5#4)/.G0G0!.$G0G0%.%2!,G0G002).#)0,%33%26)#%G0G0#)2#5)43)45G134G0G0RecommendationG0G0- (Extract from the “LUEG0“OOK)NOTES1 ITU-T Recommendation M.100 was published in Fascicle IV.1 of the
2、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 conditions remain unchanged (see below).2 In this Recommendation, t
3、he 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 form or by any means, electronic ormechanical, including ph
4、otocopying and microfilm, without permission in writing from the ITU.Fascicle IV.1 - Rec. M.100 1Recommendation M.100Fascicle IV.1 - Rec. M.100SERVICE CIRCUITSTo facilitate the general maintenance of the international telephone network, service circuits should be set upas may be necessary between re
5、levant maintenance units taking part in the international service.For the purposes of this Recommendation, a distinction is made between the following types of service circuit: Direct service circuit: a telephone or teleprinter (teletypewriter) service circuit serving only two stationsand linking th
6、em directly.Note It will also be necessary to consider the communications required by technical staff for setting upand maintaining very long circuits routed over a number of major systems in tandem, e.g.London-Singapore circuits. These may require service circuits to be interconnected. Omnibus serv
7、ice circuit (see Figure 1/M.100 below): a telephone or teleprinter (teletypewriter) servicecircuit serving more than two stations connected in series, any or all of which may make connection to theservice circuit simultaneously. Multiterminal service circuit (see Figure 2/M.100 below): a telephone o
8、r teleprinter (teletypewriter)service circuit serving more than two stations and having at least one branching point. On each branch ofthis circuit a certain number of stations can be connected in series. Every station served can enter thecircuit individually.Note Attention is drawn to the possible
9、use of selective signalling on omnibus and multiterminal servicecircuits and to the problems that may arise in achieving the necessary stability on such circuits.It is recommended that for the maintenance of international circuits:1) all attended stations should be connected direct to the public tel
10、ephone network;2) the terminal stations of an international system should be provided with a direct telephone service circuit;3) terminal and intermediate stations on an international system should be provided with an omnibustelephone service circuit;4) where the provision of direct teleprinter (tel
11、etypewriter) service circuits is impracticable or uneconomical,important repeater stations on international routes should be provided with international telex facilities;The equipment of the telegraph local end used on service telegraph circuits must be capable oftransmitting and receiving signals c
12、onforming to International Telegraph Alphabet No. 2 and must be inaccordance with the provisions of CCITT Recommendations;5) maintenance staff responsible for international circuits should have authority to make priority calls in theinternational telephone service 1;2 Fascicle IV.1 - Rec. M.100d01-s
13、cFIGURE 1/M.100.D01Fascicle IV.1 - Rec. M.100 3d02-scFIGURE 2/M.100.D026) all service circuits should in general conform to the Recommendations of the CCITT in respect of theirquality and maintenance. However, service circuits may have a restricted quality which must neverthelessbe such as to provid
14、e efficient communication when maintenance personnel have to use languages otherthan their mother tongue;7) in the event of a major interruption involving service circuits, these should be accorded priority inrestoration;8) the terminal stations of a long international submarine cable system should
15、be provided with a directteleprinter (teletypewriter) service circuit;9) terminal and intermediate stations on a long international submarine cable system should be provided withan omnibus teleprinter (teletypewriter) service circuit.The CCIR has issued Recommendation 400-2 concerning service circui
16、ts for radio-relay links. (For theconvenience of readers, this Recommendation is reproduced below. CCIR Report 444 2 also applies.)4 Fascicle IV.1 - Rec. M.100CCIR RECOMMENDATION 400-2*SERVICE CHANNELS TO BE PROVIDED FOR THE OPERATIONAND MAINTENANCE OF RADIO-RELAY SYSTEMS(Question 4/9, Geneva, 1982)
17、(1956 1959 1963 1966 1970)The CCIR,CONSIDERINGa) that service channels are required for the maintenance, supervision and control of radio-relay systems;b) that if, for any reason, the radio-relay system itself fails to function, communication between various stationsalong the route, and from those s
18、tations to other points is likely to assume special importance;c) that agreement is desirable on the number and function of the service channels to facilitate the planning ofradio-relay systems;d) that service channels will be used to provide: omnibus voice circuits, express voice circuits, supervis
19、ory circuits, control and operational circuits;e) that service channels will not be connected to the public telephone network,UNANIMOUSLY RECOMMENDSthat, on international radio-relay systems:1. all staffed stations should be connected directly to the public telephone network;2. when a radio-relay li
20、nk is extended by means of short cable sections, and these cable sections and theradio-relay link taken together constitute a regulated line section, the terminal stations of the radio-relay link itself shouldhave speaker circuits to the stations at the ends of the regulated line section;3. a teleph
21、one service channel (omnibus voice circuit) should be set up to connect together all the stations on thesystem, whether staffed or not;4. a second telephone service channel (express voice circuit) should be provided for direct telephoniccommunication between the staffed stations receiving supervisor
22、y signals;5. provisions for the transmission of supervisory and control signals should be subject to agreement between theAdministrations concerned;6. the telephone service channels should possess, whenever possible, the characteristics (excluding noise power)recommended by the CCITT for internation
23、al telephone circuits and, in particular, should be able to transmit thefrequency band 300 to 3400 Hz;7. all telephone service channels (including those used for supervisory and control circuits) up to a lengthof 280 km should, whenever possible, not exceed a mean noise power in any hour of 20 000 p
24、W0p psophometricallyweighted, at a point of zero relative level.Note Service channels may be provided over an auxiliary radio-relay system, over the main radio-relay system, or byother unrelated means, either on a primary or stand-by basis. In the case of express voice circuits, the use of regularmu
25、ltiplex channels within the telephony baseband is acceptable, where this is possible.References1 CCITT, Instructions for the International Telephone Service, Articles 46 to 49, ITU, Geneva, 1985.2 CCIR Report Service channels for analogue radio-relay systems, Vol. IX, Report 444, ITU, Geneva, 1986._
26、*This Recommendation applies to radio-relay systems which will transmit at least 60 telephone channels or a television signal andcomprise two staffed terminal stations, in which the signals are demodulated to baseband, and any number of unstaffedintermediate stations, This Recommendation applies, where appropriate, to trans-horizon radio-relay systems.
