1、 CEPT NETW23 92 E 2326434 0033362 94T NET 23 First edition: 1992 EUROPEAN TELECOMMUNICATION STANDARD Attachments to the Public Switched Telephone Network (PSTN) Category II attachment requirements for 2400 bits per second duplex modems standardized for use on the PSTN Published by: CEPT Liaison Offi
2、ce Seilerstrasse 22 CH-3008 Bern Telephone: + 41 3 1 62 20 8 1 Facsimile: + 41 31 62 20 78 Telex: 9 1 1089 CEPT CH CEPT NET*23 92 2326414 00113b3 b THE EUROPEAN CONFERENCE OF POSTAL AND TELECOMMUNICATIONS ADMINISTRATIONS (CEE) Copyright 1992 the European Conference of Postal and Telecommunications A
3、dministrations (CEPT). II NET 23 CEPT NET*23 92 = 23264LY OOLL364 712 NORMES EUROPENNES DE TLCOMMUNICATION It is recognized, in the field of telecommunications within Europe, that there is a need to create common European standards for telecommunications equipment. Such harmonization would among oth
4、er things facilitate cooperation between telecommunications equipment manu- facturers and public telecommunications network operators, create a marketplace which naturally transcends that of na- tional frontiers, enhance the efficiency of business and other communication across Europe to bring econo
5、mic benefits, and help translate the vision of a united Europe into a working reality. In 1985 an initiative by the Conference of European Posts and Telecommunications Administrations (CEPT) re- sulted in the drafting of a Memorandum of Understanding (MOU) agreeing to the mutual recognition of resul
6、ts of tests of conformity to a technical specification which would be known as a Norme Europenne de Tlcommunication (or NET). A list of signatories to the MOU is shown at the end of this introductory text. The signatories represent telecommunica- tions Administrations in most countries in Western Eu
7、rope, including EEC and EFTA Administrations. In 1986 the European Community Council Directive 86/361/EEC laid down the principles of the initial stage of the mutual recognition of type approval for telecommunications terminal equipment. The Directive imposes the obligation on EC Member States to im
8、plement the recognition of tests to common conformity specifications. I NETs 1.1 include: - - Guiding principles under which a NET is written are the need to ensure essential requirements are met. These user safety insofar as this requirement is not covered by other legal instruments (e.g. Directive
9、 73/23EEC) safety of employees of public telecommunications network operators insofar as this requirement is not covered by other legal instruments (e.g. Directive 73/23/EEC) protection of public telecommunications networks from harm interworking of terminal equipment, in justified cases - - 1.2 Eac
10、h NET constitutes part of a series of NETs prepared in response to the MOU and the EC Directive 86/361. 1.3 A NET details the requirements, and a specification of interface tests for conformance to those requirements, which a defined type of telecommunications terminal equipment is required to satis
11、fy in order to obtain authorization for connec- tion of the equipment to a defined European telecommunications network. The NET also includes, where appropriate, re- quirements made necessary in a given State by historical network peculiarities. 1.4 The existence of a NET will make it possible for a
12、n accredited laboratory in a country whose Administration has signed the MOU, to carry out tests, specified in the NET, on terminal equipment submitted to it, and to issue a test report. On the basis of the report, a competent body may then issue a certificate of conformity to the NET. There may of
13、course be cases where the laboratory itself is the competent certification authority. This certificate is then recognized as valid in all the other signatory countries, avoiding the need for the equipment to have to undergo the same tests over again each time approval is applied for in any of those
14、countries. 1.5 The common reference point which a NET represents thus offers the opportunity of substantially reducing the complexity, length and cost of approval formalities. The operators of public networks are required to make reference to relevant NETs in public supply contracts. Manufacturers a
15、re thereby enabled to compete on a more equal technical basis in the supply of terminal equipment covered by NETs. 2 TYPES OF NET The majority of NETs falls into one of the two categories: access NETs and terminal NETs. Access NET Details of the technical characteristics (electrical, mechanical and
16、access control protocol), to be offered by terminal equipment at the interface to a specific public telecommunications network are covered in an “access NET”. The objective of an access NET is to ensure no disturbance occurs to the network and to ensure interworking between network and terminal equi
17、pment so that calls can be routed successfully through the network (but without any guarantee of terminal to terminal operation). Indeed, since an access NET may have to serve a number of terminal NETs and applications which have not even been envisaged at present, it is important for the content no
18、t to include anything which is particular to a specific terminal or otherwise inhibiting to new developments. NET 23 III CEPT NETx23 92 m 232bYLY 0011365 659 m (b) Terminal NET The objective of a terminal NET is to ensure the end-to-end compatibility of a defined telecommunication ser- vice. The ter
19、minal NET should include any requirements which must be added to the corresponding access NET(s) to ensure end-to-end communication. 3 DATE OF APPLICATION The date of application of a NET is that date at which the NET is recognized as being applicable, in the signatory Administrations, for the purpo
20、ses of type approval, under the terms of Directive 86/361/EEC. 4 TRANSITION PERIOD 4.1 which there will be coexistence between the NET and any national requirements which relate to the Scope. The transition period commences at the date of application. The transition period is a period of flexibility
21、 during After the expiry of the transition period the only applicable standard within the Scope for type approval purposes will be that of the particular NET. The end of the transition period is fixed by TRAC as an objective for all signatory countries of the MOU. In some cases, however, for example
22、 when a new network has to be set up, all network operators may not be in a position to meet the objective. In such cases, the end of the transition period will be a date which is individual to the given country, and Administrations will publish the projected date by which the end of the transition
23、period can be achieved. 4.2 transition period: The following notes are offered as guidance on conformance testing of telecommunications equipment during the During the transition period, new telecommunications equipment offered by manufacturers under the Scope of this NET may be tested at a certifie
24、d laboratory located within the signatory countries, either under this NET or under the exist- ing national requirements, at the choice of the manufacturer. Testing under the NET rather than under the old requirements might offer the manufacturer the opportunity of a larger marketplace in which to s
25、ell the equipment. The transition period is also an opportunity for the public network operators to update their network. However, a national approval authority would have the facility of refusing the approval of terminal equipment, for which a certificate of conformance to a NET had been issued, if
26、 the network were not yet compatible with the terminal equipment to be con- nected. 4.3 already been approved either before application of this NET or during the transition period. The following note is offered as guidance on the supply and connection of telecommunications equipment that has After t
27、he application date of this NET, that is, during and after the transition period, the supply and connection of equipment already approved to earlier standards may continue unless the national authority terminates the validity of approvals to earlier standards for whatever reason. Figure 1 is a diagn
28、ammatic representation of the above points. 5 APPROVAL PROCEDURES Details of national type approval procedures are not contained within NETs, but are decided by national Adminis- trations. 6 REQUIREMENTS TO BE SATISFIED The scope statement defines which types of equipment must meet the requirements
29、of each NET. In addition, equip- ment may also have to satisfy the requirements in other NETs (as defined in their scope statements) or, in the absence of harmonised NETs, one or more published national standards. In the absence of any requirements in other NETs or in pub- lished national standards,
30、 no additional tests may be sought by any approval authority in the countries whose Administra- tion has signed the MOU. 7 LEGAL BASIS OF THIS INTRODUCTION TEXT This introductory text is provided for guidance, and to aid interpretation. Readers are advised that the legally binding document in the EC
31、 countries is the EEC Directive 861361. IV NET 23 CEPT NETa23 92 = 2326434 OOL33bb 595 (A) Conformance Testing Under old requirements - - - - Under this NET (B) Supply and Connection of Equipment Type- Approved before end of Transition Period + r- Data of Application of NET End of Transition Period
32、FIGURE 1 NET 23 V CEPT NETM23 92 = 232b414 OOLL367 421 m 8 SIGNATORIES OF THE MOU Austria Belgium Denmark Finland France F. R. Germany Greece Iceland Ireland IMY Luxembourg Netherlands Norway Spain Sweden Switzerland United Kingdom Portugal 9 AMENDMENTS TO A NET There may in the future be a need for
33、 amendments to a NET. Any amendments to a NET, or suspension or with- drawal of a NET, will be decided by the Technical Recommendations Application Committee (TRAC) and notified through appropriate channels including publication in the EC Official Journal. Errors detected within the text of a NET, o
34、r difficulties experienced with the application of a NET, should be reported to the following address: The Director, Office of the Secretariat, European Telecommunications Standards Institute, BP 52 F-06569 Valbonne Cedex The comments will be considered and acted upon by TRAC under an approved modif
35、ications procedure. hblic consultation will take place in respect of all but the most urgent modifications to this NET. 10 THIS NET (NET 23) 10.1 Adoption (TRAC), on the basis of an ETSETSI, on the 2 October 1991, Rhodes, Greece. The content of NET 23 was adopted by a meeting of the Technical Recomm
36、endations Application Committee 10.2 Date of Application tion period. This NET applies from 1 April 1992 within those States represented in the list of signatories, subject to the transi- 10.3 Transition Period for this NET This NET is subject to a transition period of one year from the date of appl
37、ication. After the expiry of the transition period on 3 1 March 1993 the only applicable standard for type approval purposes within the Scope will be this NET. VI NET 23 Foreword 1 2 3 3.1 3.2 4 4.1 4.2 4.2.1 4.2.2 5 5.1 5.2 5.3 5.3.1 5.3.2 5.3.2.1 5.3.2.2 5.3.3 5.4 5.5 5.6 5.7 5.7.1 5.7.2 5.8 5.8-1
38、 5.8.1.1 5.8.1.2 5.8.1.3 5.8.2 5.8.2.1 5.8.2.1.1 5.8.2.1.2 5.8.2.2 5.8.2.2.1 5.8.2.2.2 5.8.3 5.8.3.1 5.8.3.2 5.8.4 5.8.4.1 5.8.4.1.1 5.8.4.1.2 5.8.4.2 5.8.4.2.1 5.8.4.2.2 5.9 5.10 5.11 5.11.1 5.11.2 5.12 CEPT NET823 92 = 232b4L4 00LL3b 3b = TABLE OF CONTENTS Scope Normative references Definitions an
39、d abbreviations Definitions Abbreviations General requirements References to other ET General requirements for equipment connected to an analogue subscriber interface in the PSTN. NET 20: 1990: “Attachments to the Public Switched Telephone Network (PSTN); Basic attachment requirements for modems sta
40、ndardized for use on the PSTN”. CCITT Recommendation Q. 144 (1984): “Specifications of Signalling System No. 5: Line Signal Receiver”. CCITT Recommendation S.33 (1984): “Standardization of an international text for the measurement of the margin of start-stop machines using International Alphabet No.
41、 5”. CCITT Recommendation V. 14 (1 988): “Transmission of start-stop characters over synchronous bearer channels”. CCITT Recommendation V.22 (1984): “1200 bits per second duplex modem standardized for use in the General Switched Telephone Network and on point-to-point 2-wire leased telephone-type ci
42、rcuits”. CCITT Recommendation V.22bis (1988): “2400 bits per second duplex modem using the frequency division technique standardized for use on the General Switched Telephone Network and on point-to-point 2-wire leased telephone-type circuits”. CCITT Recommendation V.25 (1984): “Automatic answering
43、equipment and/or parallel automatic calling equipment on the General Switched Telephone Network including procedures for disabling of echo control devices for both manually and automatically established calls”. CCITT Recommendation V.42 (1988): “Error correcting procedures for DCEs using asynchronou
44、s-to- synchronous conversion”. CCIIT Recommendation V.52 (1984): “Characteristics of distortion and error-rate measuring apparatus for data transmission”. CCITT Recommendation V.54 (1984): “Loop Test devices for modems”. Definitions and abbreviations De$nitions For the purpose of this NET the defini
45、tions of NET 20 2 apply, together with the following. Answer mode: when calls are established with automatic facilities. a standard answer mode shall be used bv the modem at the answering station. This mode consists of conventional characteristics (e.g. use of high channel carrie; fre- quency or par
46、ticular scrambler generating polynomial) complementary to those used in the standard call mode by the modem at the calling station, in order to ensure proper connection and interworking. If calls are established on the Public Switched Telephone Network (PSTN) by operators, or for leased line opera-
47、tion, bilateral agreement on the use of call mode and answer mode shall be necessary. Call mode: when calls are established with automatic facilities, a standard call mode shall be used by the modem at the calling station. This mode consists of conventional characteristics (e.g. use of low channel c
48、arrier frequency or par- ticular scrambler generating polynomial) complementary to those used in the standard answer mode by the modem at the answering station, in order to ensure proper connection and interworking. If calls are established on the PSTN by operators, or for leased line operation, bil
49、ateral agreement on the use of call mode and answer mode shall be necessary. Data Terminal Equipment (DTE): is used to define the origin and destination of signals present at the digital interface of a modem. This expression does not require that a “commercial data terminal” be present to receive or genera- te such signals; a tester or any other suitable device may monitor or generate such signals. Initiation and Acknowledgement Signal (Sl): comprises an unscrambled repetitive double dibit pattern of 00 and 1 1 at 1200 bit/s. Modem: a f
