1、CEPT NET*E!O 92 2326434 OOLL265 778 NET 20 First edition: 1992 CEPT NET*20 92 D 2326414 00112bb b04 W NET 20 First edition: 1992 EUROPEAN TELECOMMUNICATION STANDARD Attachments to the Public Switched Telephone Network (PSTN) Basic attachment requirements for modems standardized for use on the PSTN P
2、ublished by: CEPT Liaison Office Seilerstrasse 22 CH-3008 Bern Telephone: Facsimile: Telex: 91 1089 CEPT CH + 41 31 62 20 81 + 41 31 62 20 78 CEPT NETx20 92 2326434 OOLL2b 540 THE EUROPEAN CONFERENCE OF POSTAL AND TELECOMMUNICATIONS ADMINISTRATIONS (CEPT) Copyright 1992 the European Conference of Po
3、stal and Telecommunications Administrations (CEPT). II NET 20 CEPT NET*20 92 = 2326414 0011268 487 W 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. Suc
4、h harmonization would among other 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 communicati
5、on across Europe to bring economic 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
6、the mutual recognition of results 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
7、in most countries in Western Europe, including EEC and EFA 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 obliga
8、tion on EC Member States to implement 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 leg
9、al instruments (e.g. Directive 73/23/EEC) 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,
10、 in justified cases - - 1.2 Each 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
11、 equipment is required to satisfy in order to obtain authorization for connec- tion of the equipment to a defined European telecommunications network. The NET also includes, where appropriate, requi- rements made necessary in a given State by historical network peculiarities. 1.4 The existence of a
12、NET will make it possible for an accredited laboratory in a country whose Administration has signed the MOU, to carry out tests, specified in the NET, on terminai 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 confo
13、rmity to the NET. There may of 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
14、is applied for in any of those 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 su
15、pply contracts. Manufacturers are 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. (a) Access NET Details of the technical character
16、istics (electrical, mechanical and 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
17、 between network and terminal equipment 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,
18、it is important for the content not to include anything which is particular to a specific terminal or otherwise inhibiting to new developments. NET 20 III CEPT NET*20 92 = 23261134 0031267 333 (b) Terminal NET The objective of a terminal NET is to ensure the end-to-end compatibility of a defined tel
19、ecommunication ser- vice. The terminal 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 signato
20、ry Administrations, for the purposes 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
21、period is a period of flexibility 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
22、 some cases, however, for example 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
23、 which the end of the transition 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 thi
24、s NET may be tested at a certified 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
25、 larger marketplace in which to sell 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 conform
26、ance to a NET had been issued, if 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 telecommunic
27、ations equipment that has After the 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 wha
28、tever reason. Figure 1 is a diagnammatic 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 equi
29、pment must meet the requirements 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 i
30、n pub- lished national standards, 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 l
31、egally binding document in the EC countries is the EEC Directive 86/361. IV NET 20 CEPT NETx20 92 2326414 0011270 035 W (A) Conformance Testing Under old requirements + - - - - Under this NET (BI SUDDV and Connection of Equipment Type- Approved before end of Transition Period I Data of Application o
32、f NET I End of Transition Period - -=b + - FIGURE 1 NET 20 V CEPT NET+20 72 m 232b414 0011271 T7L m 8 SIGNATORIES OF THE MOU Austria Belgium Denmark Finland France F. R. Germany Greece Iceland Ireland Italy Luxembourg Netherlands Norway Portugal Spain Sweden Switzerland United Kingdom 9 AMENDMENTS T
33、O A NET There may in the future be a need for 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
34、. Errors detected within the text of a NET, or 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 a
35、nd acted upon by TRAC under an approved modifications procedure. Public consultation will take place in respect of all but the most urgent modifications to this NET. 10 THIS NET (NET 20) 10.1 Adoption (TRAC), on the basis of a ETSETSI, on the 2 October 1991, Rhodes, Greece. The content of NET 20 was
36、 adopted by a meeting of the Technical Recommendations 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 period on 31 March 1993 the only applicable standard for type
37、approval purposes within the Scope will be this NET. Transition Period for this NET This NET is subject to a transition period of one year from the date of application. After the expiry of the transition VI NET 20 Foreword 1 2 3 3.1 3.2 4 4.1 4.2 4.3 4.3.1 4.3.1.1 4.3.1.2 4.3.2 5 5.1 5.2 5.2.1 5.2.2
38、 5.3 5.3.1 5.3.2 5.3.3 5.4 5.5 5.5.1 5.5.2 5.5.2.1 5.5.2.2 5.5.2.3 5.5.2.3.1 5.5.2.3.2 5.5.2.3.3 5.5.2.3.3.1 5.5.2.3.3.2 5.6 5.6.1 5.6.2 CEPT NETx20 92 D 2326434 O033272 908 TABLE OF CONTENTS Scope Normative references Definitions and abbreviations Definitions Abbreviations Common requirements Gener
39、al notes PSTN access requirements Information to be provided by the applicant Information required for testing purposes List of modes Other items Instructions for Use Requirements common to some Category II modems General notes Call establishment sequence based upon CCITT Recommendation V.25 191 For
40、 modems initiating calls For modems answering calls Test loop implementation based upon CCITT Recommendation V.54 I I General Remote digital test loop (loop 2) Local analogue test loop (loop 3) Threshold of received line signal detection Requirements for modems providing asynchronous tu synchronous
41、conversion based upon CCITT Recommendation V.14 SI General Transmission of start-stop characters Signalling rate ranges of the start-stop characters at the modem input Start-stop character format Asynchronous to synchronous conversion Transmitter Receiver Break signal Transmitter Receiver Performanc
42、e Overall Performance Performance in the presence of metering pulses Annex A (Informative): Testing methods for national variants for Clause 2 A. 1 General notes Page 3 4 4 5 5 6 6 6 6 6 6 6 6 6 6 6 7 7 7 7 7 8 8 8 8 8 9 9 9 9 9 9 10 10 10 10 10 10 12 12 Annex B (Normative): Testing methods for Clau
43、se 5 13 B. 1 General conditions for test 13 B.2 13 B.2.1 For modems initiating calls 13 B.2.2 For modems answering calls 13 B.3 13 B .4 14 B.5 14 B.5.1 Test patterns 14 B.5.1.1 General 14 Tests of the call establishment sequence specified in subclause 5.2 Tests tu verify the test loop implementation
44、 specified in subclause 5.3 Tests to verify the threshold of line signal detection Tests to verify the process of asynchronous to synchronous conversion specified in subclause 5.5 NET 20 1 CEPT NET*ZO 92 m 2326414 OOLL273 844 m B.5.1.2 B.5.1.3 B.5.2 B.5.3 B.5.3.1 B.5.3.1.1 B S.3.1.2 B.5.3.1.3 B.5.3.
45、1.4 B.5.3.2 B.5.3.2.1 B.5.3.2.2 B.5.3.2.3 B.5.3.2.4 B .6 B .6.1 B.6.2 B .6.4 B .6.4.1 B.6.4.2 B.6.4.3 B.6.4.4 Standard test text Discrete Test Characters (DTC) Data signalling rates Tests Transmitter tests Omission of stop elements Over-speed and under-speed capabilities Arbitrary character spacing
46、Break signal transmission Receiver tests Over-speed capability Under-speed capability Character recovery Break signal reception Performance testing methodology Genera 1 Definitions Method of measurement Test set- up Test 1 Test 2 Test 3 Annex C (Normative): Description of specialized test facilities
47、 c. 1 c.2 c.2.1 c.3 C.3.1 C.3.2 c.3.3 C.3.3.1 C.3.3.2 c.3.3.3 c.3.3.4 c.3.3.5 C.3.3.6 c.4 C.4.1 C.4.2 c.4.3 C.4.3.1 C.4.3.2 c.4.3.3 c.4.3.4 c.4.3.5 C.4.3.6 c.5 General Test set-up Simulated PSTN conditions Test Line I transmission characteristics Local line simulators Trunk network simulator Permane
48、nt impairments Insertion loss White noise Frequency offset and Phase roll Phase jitter Echo Harmonic distortion Test Line 2 transmission characteristics Local line simulators Trunk network simulator Permanent impairments Insertion loss Frequency offset and Phase roll Phase jitter Echo Harmonic disto
49、rtion Noise floor Test Line 3 transmission characteristics Annex D (Normative): Provision of test tools Annex E (Informative): Example of pro forma chart for information request Annex F (Informative): Bibliography 14 15 15 16 16 16 16 16 17 17 17 17 18 18 18 18 18 19 20 20 24 24 25 25 25 26 31 31 31 31 31 31 36 36 36 36 36 36 41 41 41 41 41 41 41 41 41 42 43 44 2 NET 20 CEPT NET*20 92 m 2326434 0011274 780 m FOREWORD This “Normes Europennes de tlcommunications (NET) has been produced by the Terminal Equipment (TE) Technical Committee of the European Telecommunications St
