1、 IEC 61746-2Edition 1.0 2010-06INTERNATIONAL STANDARD Calibration of optical time-domain reflectometers(OTDR)Part 2:OTDR for multimode fibres IEC 61746-2:2010(E)THIS PUBLICATION IS COPYRIGHT PROTECTED Copyright 2010 IEC,Geneva,Switzerland All rights reserved.Unless otherwise specified,no part of thi
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8、dback on this publication or need further assistance,please visit the Customer Service Centre FAQ or contact us:Email:csciec.ch Tel.:+41 22 919 02 11 Fax:+41 22 919 03 00 IEC 61746-2Edition 1.0 2010-06INTERNATIONAL STANDARD Calibration of optical time-domain reflectometers(OTDR)Part 2:OTDR for multi
9、mode fibres INTERNATIONAL ELECTROTECHNICAL COMMISSION XICS 33.180.01 PRICE CODEISBN 978-2-88912-026-0 Registered trademark of the International Electrotechnical Commission 2 61746-2 IEC:2010(E)CONTENTS FOREWORD.4 INTRODUCTION.6 1 Scope.7 2 Normative references.7 3 Terms,definitions and symbols.7 4 P
10、reparation for calibration.13 4.1 Organization.13 4.2 Traceability.13 4.3 Preparation.13 4.4 Test conditions.13 4.5 Documentation.13 5 Distance calibration General.14 5.1 General.14 5.2 Location deviation model.14 5.3 Using the calibration results.16 5.4 Measuring fibre length.17 6 Distance calibrat
11、ion methods.17 6.1 General.17 6.2 External source method.17 6.2.1 Short description and advantage.17 6.2.2 Equipment.17 6.2.3 Calibration of the equipment.19 6.2.4 Measurement procedure.20 6.2.5 Calculations and results.20 6.2.6 Uncertainties.21 6.3 Concatenated fibre method(using multimode fibres).
12、23 6.3.1 Short description and advantages.23 6.3.2 Equipment.23 6.3.3 Measurement procedures.24 6.3.4 Calculations and results.24 6.3.5 Uncertainties.25 6.4 Recirculating delay line method.26 6.4.1 Short description and advantages.26 6.4.2 Equipment.27 6.4.3 Measurement procedure.28 6.4.4 Calculatio
13、ns and results.28 6.4.5 Uncertainties.29 7 Vertical scale calibration General.30 7.1 General.30 7.2 Loss difference calibration.31 7.2.1 Determination of the displayed power level F.31 7.2.2 Development of a test plan.31 7.3 Characterization of the OTDR source near field.33 7.3.1 Objectives and refe
14、rences.33 7.3.2 Procedure.33 8 Loss difference calibration method.34 61746-2 IEC:2010(E)3 8.1 General.34 8.2 Long fibre method.34 8.2.1 Short description.34 8.2.2 Equipment.34 8.2.3 Measurement procedure.36 8.2.4 Calculation and results.36 Annex A(normative)Multimode recirculating delay line for dis
15、tance calibration.37 Annex B(normative)Mathematical basis.41 Bibliography.44 Figure 1 Definition of attenuation dead zone.8 Figure 2 Representation of the location deviation L(L).15 Figure 3 Equipment for calibration of the distance scale External source method.18 Figure 4 Set-up for calibrating the
16、 system insertion delay.19 Figure 5 Concatenated fibres used for calibration of the distance scale.23 Figure 6 Distance calibration with a recirculating delay line.27 Figure 7 OTDR trace produced by recirculating delay line.28 Figure 8 Determining the reference level and the displayed power level.31 Figure 9 Region A,the recommended region for loss measurement samples.32 Figure 10 Possible placement of sample points within region A.33 Figure 11 Linearity measurement with a long fibre.35 Figure 1