1、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,SU
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9、ination 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 Electr
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11、O 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
12、 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
13、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
14、 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
15、 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 fo
16、r 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