1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 - TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU-!).4%.!.#% G0G0).4%2.!4)/.!,G0G0$!4!42!.3-)33)/.G0G03934%-3.5-“%2).G0G0/&G0G0#(!%,3G0G0).G0G0$!4!42!.3-)33)/.G0G03934%-3)45G134G0G0RecommendationG0G0- (Extract from the “LUEG0“OOK)NOTES1 ITU-T Recommendation
2、 M.1320 was published in Fascicle IV.2 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 conditions remain unc
3、hanged (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 form or by an
4、y means, electronic ormechanical, including photocopying and microfilm, without permission in writing from the ITU.Fascicle IV.2 - Rec. M.1320 1Recommendation M.1320Fascicle IV.2 - Rec. M.1320NUMBERING OF CHANNELS IN DATA TRANSMISSION SYSTEMSUsing suitable modems and multiplexers it is possible to p
5、rovide for a combination of data channelsmultiplexed together to form an aggregate bit rate for transmission purposes.The principle shown in Annex A and Figure 1/M.1320 may be applied to higher bit rates as modems, etc., aredeveloped and deployed.The numbering of data channels is obtained by indicat
6、ing the multiplex channel followed by the sub-channeldata rate assigned number in accordance with the scheme contained in Table A-1/M.1320.As an example, Figure 1/M.1320 shows a data transmission system, London-Montreal 96H001, employingequipment providing for 2 channels at 2400 bit/s and one channe
7、l at 4800 bit/s forming an aggregate bit rate of9600 bit/s.For this system the channel numbering would be:London-Montreal 96H001/A2London-Montreal 96H001/B1London-Montreal 96H001/C12 Fascicle IV.2 - Rec. M.1320ANNEX A(to Recommendation M.1320)Table A-1/M.1320 shows the channel numbering scheme for d
8、ata transmission systems operated at anaggregate data rate of 9600 bit/s. The table also shows the channel numbering scheme for systems using 9600 bit/smodems operated at reduced data rates of 7200 bit/s or 4800 bit/s.TABLE A-1/M.1320Channel numbering scheme for data transmission systems using 9600
9、bit/s data modemsconforming to Recommendation V.29 1Aggregate datarateMultiplexconfigurationSub-channeldata rateMultiplexchannelChannelnumber1 9600 A A4Sub-channeldata rateAssignednumber272002400ABA3B19600 4 348004800ABA2B27200 39600 bit/s4480024002400ABCA2B1C14800 2 52400240024002400ABCDA1B1C1D16 7200 A A32400 17200 bit/s748002400ABA2B18240024002400ABCA1B1C19 4800 A A24800 bit/s1024002400ABA1B1Reference1 CCITT Recommendation 9600 bits per second modem standardized for use on point-to-point 4-wire leasedtelephone- type circuits, Vol. VIII, Rec. V.29.
