IEC TS 62367-2004 Safety aspects for xDSL signals on circuits connected to telecommunication networks (DSL Digital Subscriber Line)《连接通信网络的电路的xDSL信号的安全情况》.pdf

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

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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

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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