IEC_61280-2-8-2003.pdf

INTERNATIONALSTANDARDIEC61280-2-8First edition2003-02Fibre optic communication subsystem testprocedures Digital systemsPart 2-8:Determination of low BERusing Q-factor measurementsReference numberIEC 61280-2-8:2003(E)LICENSED TO MECON Limited.-RANCHI/BANGALOREFOR INTERNAL USE AT THIS LOCATION ONLY,SUPPLIED BY BOOK SUPPLY BUREAU.Publication numberingAs from 1 January 1997 all IEC publications are issued with a designation in the60000 series.For example,IEC 34-1 is now referred to as IEC 60034-1.Consolidated editionsThe 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,thebase publication incorporating amendment 1 and the base publication incorporatingamendments 1 and 2.Further information on IEC publicationsThe technical content of IEC publications is kept under constant review by the IEC,thus ensuring that the content reflects current technology.Information relating tothis publication,including its validity,is available in the IEC Catalogue ofpublications(see below)in addition to new editions,amendments and corrigenda.Information on the subjects under consideration and work in progress undertakenby the technical committee which has prepared this publication,as well as the listof publications issued,is also available from the following:IEC Web Site(www.iec.ch)Catalogue of IEC publicationsThe 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,technicalcommittees and date of publication.On-line information is also available onrecently issued publications,withdrawn and replaced publications,as well ascorrigenda.IEC Just Published This summary of recently issued publications(http:/www.iec.ch/online_news/justpub/jp_entry.htm)is also available by email.Please contact the CustomerService Centre(see below)for further information.Customer Service CentreIf you have any questions regarding this publication or need further assistance,please contact the Customer Service Centre:Email:custserviec.chTel:+41 22 919 02 11Fax:+41 22 919 03 00LICENSED TO MECON Limited.-RANCHI/BANGALOREFOR INTERNAL USE AT THIS LOCATION ONLY,SUPPLIED BY BOOK SUPPLY BUREAU.INTERNATIONALSTANDARDIEC61280-2-8First edition2003-02Fibre optic communication subsystem testprocedures Digital systemsPart 2-8:Determination of low BERusing Q-factor measurements IEC 2003 Copyright-all rights reservedNo part of this publication may be reproduced or utilized in any form or by any means,electronic ormechanical,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,SwitzerlandTelephone:+41 22 919 02 11 Telefax:+41 22 919 03 00 E-mail:inmailiec.ch Web:www.iec.chUFor price,see current cataloguePRICE CODECommission Electrotechnique InternationaleInternational Electrotechnical Commission LICENSED TO MECON Limited.-RANCHI/BANGALOREFOR INTERNAL USE AT THIS LOCATION ONLY,SUPPLIED BY BOOK SUPPLY BUREAU.2 61280-2-8 IEC:2003(E)CONTENTSFOREWORD.41Scope.52Definitions and abbreviated terms.52.1Definitions.52.2Abbreviations.53Measurement of low bit-error ratios.63.1General considerations.63.2Background to Q-factor.74Variable decision threshold method.94.1Overview.94.2Apparatus.124.3Sampling and specimens.124.4Procedure.124.5Calculations and interpretation of results.134.6Test documentation.174.7Specification information.175Variable optical threshold method.175.1Overview.175.2Apparatus.185.3Items under test.185.4Procedure for basic optical link.185.5Procedure for self-contained system.195.6Evaluation of results.20Annex A(normative)Calculation of error bound in the value of Q.22Annex B(informative)Sinusoidal interference method.24Bibliography.30Figure 1 A sample eye diagram showing patterning effects.8Figure 2 A more accurate measurement technique using a DSO that samples thenoise statistics between the eye centres.8Figure 3 Bit error ratio as a function of decision threshold level.10Figure 4 Plot of Q-factor as a function of threshold voltage.10Figure 5 Set-up for the variable decision threshold method.12Figure 6 Set-up of initial threshold level(approximately at the centre of the eye).12Figure 7 Effect of optical bias.17Figure 8 Set-up for optical link or device test.19Figure 9 Set-up for system test.19Figure 10 Extrapolation of log BER as function of bias.21Figure B.1 Set-up for the sinusoidal interference method by optical injection.25Figure B.2 Set-up for the sinusoidal interference method by electrical injection.27Figure B.3 BER Result from the sinusoidal interference method(data points and extrapolated line).28Figure B.4 BER versus optical power for three methods.29LICENSED TO MECON Limited.-RANCHI/BANGALOREFOR INTERNAL USE AT THIS LOCATION ONLY,SUPPLIED BY BOOK SUPPLY BUREAU.61280-2-8 IEC:2003(E)3 Table 1 Mean time for the accumulation of 15 errors as a function