1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 2 TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU4%,%2!0(94%,%2!0(G0G042!.3-)33)/.3)-5,4!.%/53G0G0#/-5.)#!4)/.“9G0G04%,%0(/.%G0G0!.$G0G04%,%2!0(/.G0G0!G0G04%,%0(/.%G0G13G0490%G0G0#)2#5)4)45G134G0G0RecommendationG0G02 (Extract from the “LUEG0“OOK)NOTES1 ITU-
2、T Recommendation R.43 was published in Fascicle VII.1 of the Blue Book. This file is an extract from theBlue 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 VII.1 - Rec. R.43 1Recommendation R.43Fascicle VII.1 - Rec. R.43SIMULTANEOUS COMMUNICATION BY TELEPHONE AND TELEGRAPHON A TELEPHONE-TYPE CIRCUIT(former CCIT Reco
5、mmendation B.50, Geneva, 1956;amended at Geneva, 1964 and 1980)The CCITT,considering(a) that the use of a leased telephone-type circuit for simultaneous communication by telephone and telegraphis envisaged in Recommendations D.1 1 and H.32 2;(b) that the CCITT has indicated conditions under which th
6、e simultaneous use of telephone-type circuits fortelephony and telegraphy is technically tolerable;(c) that standardization of the characteristics of equipment permitting simultaneous use of a telephone-typecircuit for telephony and telegraphy is not justified, but that it is necessary to limit the
7、power of the signals transmittedand to avoid the use of frequencies that will interfere with any telephone signalling equipment that may remainconnected to the telephone-type circuit;(d) that new demands for the allocation of particular frequencies for special purposes frequently arise and thenumber
8、 of frequencies used for any one purpose should not be unnecessarily extended;(e) that the systems described below may be useful when the more modern systems advocated inRecommendation H.34 3 are not feasible;unanimously declares the view(1) that in the case of the simultaneous use of a telephone-ty
9、pe circuit for telephony and telegraphy, theresulting maximum permissible 1-minute mean power loading shall not exceed 50 W0 (i.e. 13 dBm0);(2) that where frequency division multiplexing is employed, the general principle concerning the allocation oflevel to each type of service should be that the a
10、llowable mean signal power is proportional to the bandwidth assigned.This case is considered in more detail in Recommendation H.34 3, resulting in the aggregate power of the telegraphsignals being set a level not exceeding 10 W0 (i.e. approximately 20 dBm0);(3) that there should not be more than thr
11、ee circuits of this type in a frequency-division multiplexed group of12 telephone-type circuits and that the number of circuits of this type set up on a wideband carrier system should notexceed the number of supergroups in the system;(4) that the telegraph signals transmitted must not interfere with
12、 any signalling equipment that may remainconnected to the telephone-type circuit,and notesthat some Administrations have permitted the use, for simultaneous telephony and telegraphy of the frequencies1680 Hz and 1860 Hz both for amplitude and for frequency modulation.Note If circuits equipped in acc
13、ordance with the present Recommendation are used in a private network, itwill be impossible to use push-button telephone sets or multifrequency signalling (e.g. Signalling System R2) in thenetwork.References1 CCITT Recommendation General principles for the lease of international (continental and int
14、ercontinental)private leased telecommunication circuits, Rec. D.1.2 CCITT Recommendation Simultaneous communication by telephony and telegraphy on a telephone-typecircuit, Rec. H.32.3 CCITT Recommendation Subdivision of the frequency band of a telephone-type circuit between telegraphy andother services, Rec. H.34.
