1、INTERNATIONAL TELECOMMUNICATION UNION)45G134 3 TELECOMMUNICATIONSTANDARDIZATION SECTOROF ITU4%,%2!0(9!,0(!“%4)#!,G0G04%,%2!0(G0G04%2-).!,%15)0-%.4#!,).G0G0!.$G0G0!.37%2).G0G0).G0G04(%G0G04%,%8.%47/2+G0G07)4(G0G0!54/-!4)#G0G04%2-).!,%15)0-%.4)45G134G0G0RecommendationG0G03 (Extract from the “LUEG0“OOK
2、)NOTES1 ITU-T Recommendation S.19 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 copy
3、right conditions 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 ut
4、ilized in any form or by any means, electronic ormechanical, including photocopying and microfilm, without permission in writing from the ITU.Fascicle VII.1 - Rec. S.19 1Recommendation S.19Fascicle VII.1 - Rec. S.19CALLING AND ANSWERING IN THE TELEX NETWORKWITH AUTOMATIC TERMINAL EQUIPMENT(Geneva, 1
5、980)1 General1.1 This Recommendation describes a method of originating and answering calls on the 50-baud telex network bymeans of an automatic terminal using a simple telegraph-type interface for the exchange of data or messages.1.2 The equipment that processes these data or messages at the termina
6、l is referred to as the data terminalequipment (DTE). It should be able to carry out automatically all the operations required to set up and clear down callsas well as the sending and receiving of information at 50 bauds on the telex network.1.3 The data circuit terminating equipment (DCE) constitut
7、es the frontier between the DTE and the telex networkand offers the possibility of remote maintenance. The DCE effects all signal conversions between the DTE and thetelex subscriber line. The DCE may be either a separate unit or a built-in component of the DTE.2 DCE/DTE interface2.1 The interchange
8、circuits used for the interface (if any) between the DCE and the DTE are defined inRecommendation V.24 1 and comply with the technical specifications in either Recommendation V.28 2 orRecommendation V.10 3. Thus the correspondence between the voltages and the significant states is as shown inTable 1
9、/S.16.2.2 The DCE/DTE interface consists of three circuits: CT 103 and 104 for the transmission and reception of bothdata and control signals and CT 102 for the signal ground or common return. Figure 1/S.19 illustrates the interfaceconfiguration.2.3 In addition to its use for sending data or message
10、s once a call has been established, CT 103 carries all thecontrol signals produced by the DTE and needed by the telex network to set up and clear down connections. SimilarlyCT 104, in addition to its use for receiving data or messages once a call has been established, carries all the controlsignals
11、produced by the DCE and needed by the network to set up and clear down connections.2.4 During a call that has been set up and in the setting-up phase, as well as in all intervals between signals, theDTE maintains CT 103 and the DCE maintains CT 104 on Z polarity.2 Fascicle VII.1 - Rec. S.193 Signall
12、ing3.1 This interface may be used with any of the telex signalling variants in use in national networks.3.2 The signalling between the DCE and the national telex exchange is not standardized by the CCITT. Thesignalling protocol shown in the timing diagram (Figure 3/S.19) is only an example. However,
13、 since it is based on typeA signalling, for Type B signalling the call establishment phase should be read as shown in Figure 2/S.19.3.3 Figure 3/S.19 shows CT 103 (forward path) and CT 104 (backward path) for both the calling and called DTEs.Consequently it covers both calling and answering with an
14、automatic terminal, but the procedures described areapplicable to a calling or called DTE in communication with a DTE operated in accordance with one of the proceduresdescribed in Recommendation S.16 or manually. The particular case shown is that of a successful call with clearinginitiated by the ca
15、lling DTE.3.4 The SSSS sequence (four times combination No. 19 in International Telegraph Alphabet No. 2) normallyprecedes and announces the exchange of data, which may commence after a delay of 500 ms, as specified inRecommendation S.15. This sequence may be omitted where an exchange of message in
16、ITA2 is to take place,providing disabling of the answer-back function is not considered necessary.3.5 The DTE must comply with Recommendation U.40 4 concerning reactions to ineffective call attempts. Itmust be able to interpret at least the following service signals: OCC, ABS, NA, NP, NC, NCH, DER.3
17、.6 If a call collision is detected, the DTE must abandon its call attempt to permit acceptance of the incoming call.Fascicle VII.1 - Rec. S.19 3References1 CCITT Recommendation List of definitions for interchange circuits between data terminal equipment and datacircuit terminating equipment, Rec. V.
18、24.2 CCITT Recommendation Electrical characteristics for unbalanced double-current interchange circuits, Rec.V.28.3 CCITT Recommendation Electrical characteristics for unbalanced double-current interchange circuits forgeneral use with integrated circuit equipment in the field of data communications, Rec. V.10.4 CCITT Recommendation Reactions by automatic terminals connected to the telex network in the event ofineffective call attempts or signalling incidents, Rec. U.40.
