1、TECHNICAL SPECIFICATION IECTS 62367 Pre-Standard First edition 2004-01 Safety aspects for xDSL signals on circuits connected to telecommunication networks (DSL: Digital Subscriber Line) Reference number IEC/TS 62367:2004(E)Publication numbering As from 1 January 1997 all IEC publications are issued
2、with a designation in the 60000 series. For example, IEC 34-1 is now referred to as IEC 60034-1. Consolidated editions The IEC is now publishing consolidated versions of its publications. For example, edition numbers 1.0, 1.1 and 1.2 refer, respectively, to the base publication, the base publication
3、 incorporating amendment 1 and the base publication incorporating amendments 1 and 2. Further information on IEC publications The technical content of IEC publications is kept under constant review by the IEC, thus ensuring that the content reflects current technology. Information relating to this p
4、ublication, including its validity, is available in the IEC Catalogue of publications (see below) in addition to new editions, amendments and corrigenda. Information on the subjects under consideration and work in progress undertaken by the technical committee which has prepared this publication, as
5、 well as the list of publications issued, is also available from the following: IEC Web Site (www.iec.ch) Catalogue of IEC publications The on-line catalogue on the IEC web site (http:/www.iec.ch/searchpub/cur_fut.htm) enables you to search by a variety of criteria including text searches, technical
6、 committees and date of publication. On-line information is also available on recently issued publications, withdrawn and replaced publications, as well as corrigenda. IEC Just Published This summary of recently issued publications (http:/www.iec.ch/online_news/ justpub/jp_entry.htm) is also availab
7、le by email. Please contact the Customer Service Centre (see below) for further information. Customer Service Centre If you have any questions regarding this publication or need further assistance, please contact the Customer Service Centre: Email: custserviec.ch Tel: +41 22 919 02 11 Fax: +41 22 91
8、9 03 00TECHNICAL SPECIFICATION IEC TS 62367 Pre-Standard First edition 2004-01 Safety aspects for xDSL signals on circuits connected to telecommunication networks (DSL: Digital Subscriber Line) PRICE CODE IEC 2004 Copyright - all rights reserved No part of this publication may be reproduced or utili
9、zed in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher. International Electrotechnical Commission, 3, rue de Varemb, PO Box 131, CH-1211 Geneva 20, Switzerland Telephone: +41 22 919 02 11 Telefax: +41 22 919 0
10、3 00 E-mail: inmailiec.ch Web: www.iec.ch M For price, see current catalogue Commission Electrotechnique Internationale International Electrotechnical Commission 2 TS 62367 IEC:2004(E) CONTENTS FOREWORD.3 INTRODUCTION.5 1 Scope.6 2 Normative references .6 3 Terms, definitions and abbreviations 6 4 x
11、DSL signals on circuits connected to telecommunication networks7 Annex A (informative) xDSL telecommunication systems .8 A.1 Introduction 8 A.2 General description 8 A.3 Peak-to average ratio and CF.9 A.4 CF distribution10 A.5 Line termination impedance12 A.6 Measurement of xDSL parameters12 Bibliog
12、raphy13 Figure A.1 Typical configuration of an xDSL system.8 Figure A.2 Typical xDSL (VDSL) signal in the time-domain 9 Figure A.3 Probability of symbol with CF x .11 Figure A.4 Inter-arrival time of symbol with CF x (DMT-symbol rate = 4 kHz) 11TS 62367 IEC:2004(E) 3 INTERNATIONAL ELECTROTECHNICAL C
13、OMMISSION _ SAFETY ASPECTS FOR XDSL SIGNALS ON CIRCUITS CONNECTED TO TELECOMMUNICATION NETWORKS (DSL: DIGITAL SUBSCRIBER LINE) FOREWORD 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC Nati
14、onal Committees). The object of IEC is to promote international co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports, Publi
15、cly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with may participate in this preparatory work. International, governmental and non- govern
16、mental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for Standardization (ISO) in accordance with conditions determined by agreement between the two organizations. 2) The formal decisions or agreements of IEC on
17、 technical matters express, as nearly as possible, an international consensus of opinion on the relevant subjects since each technical committee has representation from all interested IEC National Committees. 3) IEC Publications have the form of recommendations for international use and are accepted
18、 by IEC National Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any misinterpretation by any end user. 4) In order to promote international
19、uniformity, IEC National Committees undertake to apply IEC Publications transparently to the maximum extent possible in their national and regional publications. Any divergence between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter
20、. 5) IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any equipment declared to be in conformity with an IEC Publication. 6) All users should ensure that they have the latest edition of this publication. 7) No liability shall attach to IEC or its dire
21、ctors, employees, servants or agents including individual experts and members of its technical committees and IEC National Committees for any personal injury, property damage or other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and expenses arisin
22、g out of the publication, use of, or reliance upon, this IEC Publication or any other IEC Publications. 8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is indispensable for the correct application of this publication. 9) Attention is dr
23、awn to the possibility that some of the elements of this IEC Publication may be the subject of patent rights. IEC shall not be held responsible for identifying any or all such patent rights. The main task of IEC technical committees is to prepare International Standards. In exceptional circumstances
24、, a technical committee may propose the publication of a technical specification when the required support cannot be obtained for the publication of an International Standard, despite repeated efforts, or the subject is still under technical development, or where, for any other reason, there is the
25、future but no immediate possibility of an agreement on an International Standard. Technical specifications are subject to review within three years of publication to decide whether they can be transformed into International Standards. IEC-TS 62367, which is a technical specification, has been prepar
26、ed by IEC technical committee 108: Safety of electronic equipment within the field of audio/video, information technology and communication technology. This technical specification is a pre-standard publication which may be updated in the future as an International Standard. 4 TS 62367 IEC:2004(E) T
27、he text of this technical specification is based on the following documents: Enquiry draft Report on voting 108/61/DTS 108/90/RVC Full information on the voting for the approval of this technical specification can be found in the report on voting indicated in the above table. This publication has be
28、en drafted in accordance with the ISO/IEC Directives, Part 2. In this standard, terms defined in 1.2 of IEC 60950-1are printed in SMALL CAPITALS. The committee has decided that the contents of this publication will remain unchanged until 2007. At this date, the publication will be transformed into a
29、n International Standard; reconfirmed; withdrawn; replaced by a revised edition, or amended.TS 62367 IEC:2004(E) 5 INTRODUCTION xDSL signals are high-speed telecommunication signals that may be present on a telecommunication line, together with: analogue PSTN (Public Switched Telephone Network); ISD
30、N (Integrated Services Digital Network) signals; or a d.c. power-feeding component. An xDSL signal is characterised by an amplitude of the order of 3 V r.m.s. with superimposed spikes having very short duration (about 1 s) and peak values not exceeding 30 V. When combined with other services as abov
31、e, the peak voltage can very occasionally exceed the limits for a TNV-3 CIRCUIT. However the excursions above these limits consist of these very short duration spikes. There are no published documents from IEC on the effect of such spikes on the human body, but experience with xDSL is that the safet
32、y risk, if any, is very small because of: the low power of the spikes; and the limited accessibility of TNV circuits. The amplitude and probability of the spikes have been calculated as follows: amplitude up to 15V/1 s with a probability of occurrence of one every few seconds to every few minutes; a
33、mplitude up to 20V/1 s with a probability of occurrence of one every few hours; amplitude up to 27V/1 s with a probability of occurrence of one every few years. Annex A gives more detail on the operation of xDSL telecommunication systems. 6 TS 62367 IEC:2004(E) SAFETY ASPECTS FOR XDSL SIGNALS ON CIR
34、CUITS CONNECTED TO TELECOMMUNICATION NETWORKS (DSL: DIGITAL SUBSCRIBER LINE) 1 Scope This technical specification addresses the safety implications of having xDSL signals on circuits in equipment connected to a TELECOMMUNICATION NETWORK, and gives rules for dealing with such equipment in the context
35、 of the IEC 60950 series. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
36、IEC 60950 (all parts), Information technology equipment Safety IEC 60950-1 (all parts), Information technology equipment Safety Part 1: General requirements 3 Terms and definitions, and abbreviations For the purposes of this document, the terms and definitions in the IEC 60950 series and the followi
37、ng abbreviations apply. ADSL Asymmetric Digital Subscriber Line CF Crest Factor CO Central Office CPE Customer Premises Equipment DMT Discrete Multi Tone DSL Digital Subscriber Line HDSL High Speed Digital Subscriber Line IEC International Electrotechnical Commission ISDN Integrated Services Digital
38、 Network ITU International Telecommunication Union ITU-T Telecommunication Standardization Sector of ITU NT Network Termination PAR Peak to Average Ratio PSTN Public Switched Telephone Network QAM Quadrature Amplitude Modulation RSS Remote Signal Source SDSL Symmetric Digital Subscriber Line TNV Tel
39、ecommunication Network Voltage VDSL Very-high-bit-rate Digital Subscriber LineTS 62367 IEC:2004(E) 7 4 xDSL signals on circuits connected to telecommunication networks Based on the information presented in Annex A, it is recommended that for equipment within the scope of the IEC 60950 series of stan
40、dards, the following rules be applied for xDSL signals on circuits connected to telecommunication networks. Rule 1: Circuits carrying xDSL signals are classified as either TNV-1 CIRCUITS or TNV-3 CIRCUITS, depending on the normal operating voltage of the circuit. Rule 2: When a) assessing the voltag
41、es in circuits carrying xDSL signals with respect to the limits in 2.3.1 of IEC 60950-1, and when b) determining the WORKING VOLTAGE of insulation in accordance with the IEC 60950 series, the voltage of xDSL signals is regarded as zero and has no impact on the classification of the circuits. 8 TS 62
42、367 IEC:2004(E) Annex A (informative) xDSL telecommunication systems A.1 Introduction This annex describes the structure of xDSL signals, and explains why it is considered that there is no shock hazard associated with xDSL signals. xDSL is a general expression for high-speed telecommunication signal
43、s such as ADSL (Asymmetric Digital Subscriber Line), VDSL (Very-high-bit-rate DSL), HDSL (High-Speed- DSL), SDSL (Symmetric DSL), etc. (see Figure A.1). xDSL signals are generally transmitted between the CO (Central Office) or RSS (Remote Signal Sources, such as repeaters and optical network units i
44、n street cabinets) and the CPE (customer premises equipment). These signals are transmitted over existing wires and cables. ADSL and VDSL signals may be transmitted in combination with existing telephone services such as PSTN and ISDN. In other cases the telecommunication line only carries the xDSL
45、signal together with d.c. to power the CPE from the CO. Figure A.1 Typical configuration of an xDSL system A.2 General description An xDSL signal consists of an a.c. waveform with complex amplitude and frequency behaviour due to the use of special modulation techniques. Although xDSL signals are fun
46、ctional communication signals within a broadband frequency spectrum, their appearance on an oscilloscope is like “white-noise”, for example, a small average or r.m.s. value with occasional spikes (see Figure A.2). CO or RSS Equipment CO or RSSEnd modem CPE Access network Splitter DSL port Splitter C
47、PE End modem PSTN- /ISDN- line ISDN-NT or telephone Digital port PSTN- /ISDN port PSTN- /ISDN port Digital port DSL port Line loop IEC 029/04TS 62367 IEC:2004(E) 9 r.m.s. value equals 1 VDSL transmission 6 400 6 600 6 800 7 000 7 200 7 400 7 600 Time s 4 3 2 1 0 1 2 3 4 IEC 030/04 Figure A.2 Typical
48、 xDSL (VDSL) signal in the time-domain The magnitude of an xDSL signal is defined in the relevant functional standard by its mean power into a resistive load, within a specified frequency band. This mean power, in dBm, can be expressed as a well defined r.m.s. voltage value, in general in the order
49、of a few volts. Of all xDSL signals, the worst case value, for ADSL combined with PSTN (ITU-T Recommendation G.992.1- Annex A), is 20,4 dBm into 100 or 3,31 V r.m.s. in the downstream direction (from CO to CPE), and 12,5 dBm into 100 or 1,33 V r.m.s. in the upstream direction (from CPE to CO). The peak voltage however can be higher and depends on: peak-to average ratio (PAR) or crest factor (CF); CF distri
