1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 - TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU-!).4%.!.#%G0 ).4%2.!4)/.!,G0G042!.3-)33)/.G0G03934%-3!.!,/5%G9“2).).G0G0).4%2.!4)/.!,2/50 G0G0350%22/50 G0G0%4# ,).+3G0G0).4/G0G03%26)#%)45G134G0G0RecommendationG0G0- (Extract from the “LUEG0“OOK)NOTES1 ITU-
2、T Recommendation M.460 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 condit
3、ions 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 an
4、y form or by any means, electronic ormechanical, including photocopying and microfilm, without permission in writing from the ITU.Fascicle IV.1 - Rec. M.460 1Recommendation M.460Fascicle IV.1 - Rec. M.460BRINGING INTERNATIONAL GROUP, SUPERGROUP, ETC.,LINKS INTO SERVICE1 Preliminary exchange of infor
5、mationThe technical services concerned nominate the control and sub-control stations for the link to be brought intooperation in accordance with Recommendations M.80 and M.90.The technical services should indicate the routing to be followed and the method given inRecommendation M.570 may be applied.
6、 In the case of group or supergroup links, they will mutually agree on the pilotor pilots to be used.Note When group, supergroup, etc. links are used to provide the terrestrial links to a time division multipleaccess (TDMA) satellite system, the pilots are not transmitted over the satellite section.
7、 An alternative method ofsupervision for the individual circuits is described in Recommendation Q.33 1.In determining the routing of group links, in order to avoid interference between the pilots on two supergrouplinks, the technical services will try to arrange that position No. 3 is not occupied b
8、y the same group link on twosupergroup links. (Where this is impossible, the supergroup pilot should be blocked at the through-group connectionpoint.)Information necessary for the control station, which will be entered on a routing form see specimens inAppendix I (supergroup routing form) and Append
9、ix III (A or B) (group routing form) of this Recommendation isindicated below: routing of the link, names of control and sub-control stations, through-connection points, points where regulators are fitted.The overall routing form for the entire link is drawn up by the control station on the basis of
10、 informationfurnished by its technical service and by each sub-control station for the sections for which the latter is responsible.When the group link is assigned its designation (according to Recommendation M.140, 5 and 6), theAdministration with control station responsibility will assemble the ne
11、cessary technical and operational information.This is entered into the list of Related information (as defined in Recommendation M.140, 7) which consists of theitems shown in Annex A.2 Frequencies and levels of group, supergroup, etc., pilots2.1 Details of the recommended frequency and level of pilo
12、ts are given in Table 1/M.460.The specifications of terminal equipments provide that for every group or supergroup two pilots can besimultaneously transmitted. However, the normal case is that only one is being transmitted.Note Special considerations apply to the use of group and supergroup pilots i
13、f circuits are to be providedusing Signalling System R2. Group and supergroup pilots placed at 140 Hz from a virtual carrier frequency areincompatible with signalling at 3825 Hz. Hence, the pilot at 84.140 kHz should not be applied to groups in whichchannel 6 is to be operated with this out-of-band
14、signalling. Similarly, the pilot on 411.860 kHz should not be applied tosupergroups in which channel 1 of the group in the group 3 position is to be operated with signalling at 3825 Hz.2 Fascicle IV.1 - Rec. M.460TABLE 1/M.4602.2 Level tolerances for transmitted pilots2.2.1 At the point where a pilo
15、t is injected, its level should be so adjusted that its measured value is within 0.1 dBof its nominal value. The measuring equipment used for making this measurement must give an accuracy of atleast 0.1 dB.2.2.2 The change in output level of the pilot generator with time (which is a factor included
16、in equipmentspecifications) must not exceed 0.3 dB.2.2.3 The total maximum variation resulting from 2.2.1 and 2.2.2 above will be 0.5 dB. It is advisable to have adevice to give an alarm when the variation at the generator output exceeds these limits, the zero of the warning devicebeing aligned as a
17、ccurately as possible with the lining-up level of the transmitted pilot.2.3 Frequency tolerances for transmitted pilotsThe permissible frequency tolerances for transmitted pilots are as follows: 84 kHz and 444 kHz (if used as reference pilots for 16-channel systems). 1 Hz 84.080 kHz and 411.920 kHz
18、pilots . 1 Hz 84.140 kHz and 411.860 kHz pilots . 3 Hz 104.080 kHz and 547.920 kHz pilots . 1 Hz 1552-kHz pilot 2 Hz 11 096-kHz pilot. 10 HzGroup, supergroup and mastergroup pilots forFrequency (kHz) Power levela)8 ch. and12 ch.16 ch. dBm0Basic group (60-108 kHz) 84.080 84b)2084.140 25104.080 20Basi
19、c supergroup 411.860 25411.920 444c)20547.920 20Basic mastergroup 1 552 20Basic supermastergroup . 11 096 20Basic 15 supergroup assemble . 1 552 20a)To avoid errors in interpreting measurement results, the results of measurements on pilots will be stated in terms of the departurefrom the nominal pil
20、ot level in dBm at that particular point.b)A pilot of 84 kHz is normally used. A different frequency can be used by agreement between Administrations.c)A pilot of 444 kHz with a power level of 20 dBm0 is used.Fascicle IV.1 - Rec. M.460 33 Frequencies and levels of test signalsReference measurements
21、for a link and its component sections are made at some or all of the followingfrequencies: supermastergroup link:8516, 9008, 11 096, 11 648, 12 388 kHz; 15 supergroup assembly link:312, 556, 808, 1056, 1304, 1552, 2048, 2544, 3040, 3536, 4028 kHz; mastergroup link:814, 1056, 1304, 1550, 1800, 2042 k
22、Hz; supergroup link (4-kHz channels):313, 317, 333, 381, 412, 429, 477, 525, 545, 549 kHz; supergroup link (3-kHz channels or 3+4-kHz channels):312.1, 313, 317, 333, 381, 412, 429, 477, 525, 545, 549, 551.9 kHz; group link (4-kHz channels):61, 63, 71, 79, 84, 87, 95, 103, 107 kHz1); group link (3-kH
23、z channels):60.1, 60.6, 61, 63, 71, 79, 84, 87, 95, 103, 107, 107.3, 107.9 kHz1).Administrations may also make measurements at other frequencies as considered necessary. In the case ofgroup and supergroup links of simple constitution, three measuring frequencies (midband and at the two edges) maysuf
24、fice.The overall loss will be measured by means of a test frequency being equal or very close to the reference pilotfrequency.The level of the test signal to be used for the measurements will be 10 dBm0.4 Reference measurements for a linkThe measurements described in 7.2 below for lining-up also con
25、stitute reference measurements. These datashould be recorded at every group, supergroup, etc. sub-control station and in the through-connection stations adjacent tofrontiers and, on request, forwarded to the control station which then can draw up a line-up record.5 Some features of a multiple destin
26、ation unidirectional transmission link as might be provided by acommunication-satellite systemThis section refers to Figure 1/M.460, which is drawn in terms of a supergroup. An analogous arrangement canoccur for groups or, in principle, for higher-order assemblies. There is no loss of generality in
27、describing thearrangement of a supergroup._1)If the group-measuring frequencies are generated by applying 1020 Hz to the input of channel modulating equipment, specialprecautions will have to be taken at the receiving end to prevent carrier leak from affecting the readings of the measuringequipment.
28、 In these circumstances, the measuring device must be of the selective kind. For further information about the choice ofthe test signal frequency, refer to Recommendation O.6 2.4 Fascicle IV.1 - Rec. M.460d01-scFIGURE 1/M.460.D015.1 In the example the supergroup is assembled in London and portions o
29、f it appear in three other places. Hencethe designatory letter M standing for MULTIPLE DESTINATION.5.2 In the return directions of transmission for any or all of the groups in this supergroup, the transmission pathmay be quite different and will not necessarily bear any relationship to the direction
30、 illustrated. Hence the designatoryletter U standing for UNIDIRECTIONAL.5.3 The supergroup may be set up initially with only some of the destinations, for example, Montreal may beconnected some time, say a year or so, after Bogota and Lusaka.Furthermore, a destination may alter the amount of bandwid
31、th it exploits, e.g. Bogota may initially deriveGroups 1 and 2, Group 5 being derived some time later.5.4 The portions of the supergroup defined by the stations 1-2-3, 4-5-6, and 8-9 are supergroup sections which areto be treated in the way described in the following paragraphs of this Recommendatio
32、n.5.5 The routings connecting stations 3, 4, 7 and 8 to their corresponding earth stations A, B, C and D can bemarkedly dissimilar. For example, the routing to control station 4 from earth station B need not resemble in any way theanalogous routing from earth station D to control station 8. Control
33、station 4 may be at the earth station, that is, thedistance between B and 4 is zero whereas the distance between D and 8 may be several hundreds of miles perhaps andmay be routed over a variety of coaxial line or radio-relay systems.5.6 The portion 1-2-3 is referred to as a common path. Operations o
34、n the common path can affect all destinationswhereas operations on the other paths (4-5-6 and 8-9) can affect only one destination.5.7 Station 3 is likely to have a community of interest with each of stations 4, 7 and 8. This is not necessarily solikely among 4, 7 and 8 themselves.Fascicle IV.1 - Re
35、c. M.460 55.8 The stations 4, 7 and 8 each receive the whole of the basic supergroup band from station 3 though none ofthem exploits the whole of it.The above-mentioned distinctive features of a multiple destination unidirectional group, supergroup, etc. (suchas might be provided by a communication-
36、satellite system) make special procedures for lining-up and maintenance anecessity. This fact is taken into account below.6 Organization of the control of an international group, supergroup, etc.6.1 Classes of station6.1.1 As far as international cooperation is concerned, only two classes of through
37、-connection stations need bedesignated by any country:a) stations which exercise control functions, i.e. group, supergroup, etc., control stations and group,supergroup, etc., sub-control stations;b) attended stations nearest the frontier, which in this Recommendation are referred to as frontier stat
38、ions.6.1.2 In accordance with Recommendations M.80 and M.90 the station at each end of the group, supergroup, etc., isthe control station for the receiving direction of transmission and the terminal sub-control station for the sendingdirection. Stations having control functions in intermediate count
39、ries are group, supergroup, etc., intermediatesub-control stations. Other stations involved in international maintenance are frontier stations.6.1.3 In general, a transit country will have one station with control functions or one with sub-control functions andtwo frontier stations. A country in whi
40、ch the group, supergroup, etc., terminates has only one frontier station. In somecountries, a station with control functions or sub-control functions and a frontier station will be the same.6.2 Classes of group, supergroup, etc. sectionFor the purposes of setting-up, lining-up and subsequent mainten
41、ance, an international group, supergroup, etc.,link is subdivided into national sections, international sections and main sections as defined in Recommendation M.300.These terms are illustrated in Figure 2/M.460.d02-scFIGURE 2/M.460.D026 Fascicle IV.1 - Rec. M.4606.3 Organization of control function
42、sThe terminal stations of each national, international and main section will be appointed as a control orsub-control station for that class of section with which they are concerned. However, as a consequence of the definitionsof national, international and main sections of a link some stations will
43、be nominated for more than one control orsub-control function. For example, station S in Figure 2/M.460 is: control station for main section Q-S, sub-control station for main section S-T, control station for national section R-S.6.4 Control functions in case of multiple destination (MU) transmission
44、 linksThe multiple destination unidirectional section defined by the through-connection stations nearest to the earthstations is to be a main section. The full designation is: multiple destination unidirectional main group, supergroup, etc.,section.In the example (Figure 1/M.460), stations 3, 4, 7 a
45、nd 8 serve to define this main section.The through-connection stations defining the extent of the MU main section will be assigned the controlfunctions normally called for in the case of group, supergroup, etc. sections.It follows that if the group, supergroup, etc., appears in the earth station at
46、the basic group, supergroup, etc.,frequencies, the earth station must function as a main section control or sub-control station for the multiple destinationunidirectional section.A very clear distinction must be made between: satellite control stations that might be concerned with baseband-to-baseba
47、nd response (for example), group, supergroup, etc., control stations concerned with the performance of the group, supergroup, etc.(These are places where the bands 60-108, 312-552 kHz, etc., are normally accessible.) Such controlstations are not called satellite stations because group, supergroup, e
48、tc., control functions are independentof the means of transmission.In addition: the sub-control station for the MU main group, supergroup, etc., section is designated the send referencestation for the MU main group, supergroup, etc., section (in the example, station 3 is so designated).Again the dis
49、tinction must be maintained between any coordination stations nominated for the satellite system(concerned with baseband, etc., matters) and MU main group, supergroup, etc., section reference stations. If stations 3,4, 7 and 8 are physically in earth stations A, B, C and D respectively, then those earth stations will also have to functionas the MU main section reference stations in addition to other responsibilities associated with coordination functions ofthe satellite system.In addition to the
