1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationCalibration of optical time-domain reflectometers (OTDR)Part 1: OTDR for single-mode fibresBS EN 61746-1:2011National forewordThis British Standard is the UK implementation of EN
2、 61746-1:2011. It is identical to IEC 61746-1:2009. BS EN 61746-1:2011 along with BS EN 61746-2 (yet to publish) will supersede BS EN 61746:2005.The UK participation in its preparation was entrusted to Technical Committee GEL/86, Fibre optics.A list of organizations represented on this committee can
3、 be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. BSI 2011ISBN 978 0 580 57353 8 ICS 33.180.01Compliance with a British Standard cannot confer immunity from legal obliga
4、tions.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 30 June 2011.Amendments issued since publicationAmd. No. Date Text affectedBRITISH STANDARDBS EN 61746-1:2011EUROPEAN STANDARD EN 61746-1 NORME EUROPENNE EUROPISCHE NORM March 2011 CENELEC
5、 European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Management Centre: Avenue Marnix 17, B - 1000 Brussels 2011 CENELEC - All rights of exploitation in any form and by any means reserved worldwide f
6、or CENELEC members. Ref. No. EN 61746-1:2011 E ICS 33.180.01 Supersedes EN 61746:2005 (partially)English version Calibration of optical time-domain reflectometers (OTDR) - Part 1: OTDR for single-mode fibres (IEC 61746-1:2009) talonnage des rflectomtres optiques dans le domaine temporel (OTDR) - Par
7、tie 1: OTDR pour fibres unimodales (CEI 61746-1:2009) Kalibrierung optischer Rckstreumessgerte (OTDR) - Teil 1: OTDR fr Einmodenfasern (IEC 61746-1:2009) This European Standard was approved by CENELEC on 2011-01-02. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which
8、stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member. This European St
9、andard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the Central Secretariat has the same status as the official versions. CENELEC members are the nat
10、ional electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Sp
11、ain, Sweden, Switzerland and the United Kingdom. BS EN 61746-1:2011EN 61746-1:2011 - 2 - Foreword The text of document 86/347/FDIS, future edition 1 of IEC 61746-1, prepared by IEC TC 86, Fibre optics, was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 61746-1 on 2011-0
12、1-02. This European Standard partially supersedes EN 61746:2005. The main technical changes to EN 61746:2005 are: the adaptation of Clause 4; the deletion of Clause 10; the adaptation of some definitions and calculations; the change of graphical symbology to IEC/TR 61930. Attention is drawn to the p
13、ossibility that some of the elements of this document may be the subject of patent rights. CEN and CENELEC shall not be held responsible for identifying any or all such patent rights. The following dates were fixed: latest date by which the EN has to be implemented at national level by publication o
14、f an identical national standard or by endorsement (dop) 2011-10-02 latest date by which the national standards conflicting with the EN have to be withdrawn (dow) 2014-01-02 Annex ZA has been added by CENELEC. _ Endorsement notice The text of the International Standard IEC 61746-1:2009 was approved
15、by CENELEC as a European Standard without any modification. In the official version, for Bibliography, the following notes have to be added for the standards indicated: 2 IEC 60793-1-1 NOTE Harmonized as EN 60793-1-1. 3 IEC 60794-1-2:2003 NOTE Harmonized as EN 60794-1-2:2003 (not modified). 4 IEC 60
16、825-1 NOTE Harmonized as EN 60825-1. 5 IEC 60825-2 NOTE Harmonized as EN 60825-2. 6 IEC 61280-1-3:1998 NOTE Harmonized as EN 61280-1-3:1999 (not modified). 7 IEC 61300-3-2 NOTE Harmonized as EN 61300-3-2. 8 IEC 61300-3-6 NOTE Harmonized as EN 61300-3-6. _ BS EN 61746-1:2011- 3 - EN 61746-1:2011 Anne
17、x ZA (normative) Normative references to international publications with their corresponding European publications 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 editi
18、on of the referenced document (including any amendments) applies. NOTE When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD applies. Publication Year Title EN/HD Year IEC 60793-1-40 (mod) - Optical fibres - Part 1-40: Measurement methods
19、 and test procedures - Attenuation EN 60793-1-40 - IEC 60793-2-50 - Optical fibres - Part 2-50: Product specifications - Sectional specification for class B single-mode fibres EN 60793-2-50 - ISO/IEC 17025 - General requirements for the competence of testing and calibration laboratories EN ISO/IEC 1
20、7025 - ITU-T Recommendation G.650.1 2004 Definitions and test methods for linear, deterministic attributes of single-mode fibre and cable - - ITU-T Recommendation G.650.2 2002 Definitions and test methods for statistical and non-linear related attributes of single-mode fibre and cable - - BS EN 6174
21、6-1:2011 2 61746-1 IEC:2009(E) CONTENTS INTRODUCTION. 8 1 Scope.9 2 Normative references.9 3 Terms, definitions and symbols 9 4 Preparation for calibration.16 4.1 Organization .16 4.2 Traceability. 16 4.3 Preparation. 16 4.4 Test conditions . .16 4.5 Documentation .16 5 Distance calibration General
22、.17 5.1 General .17 5.2 Location deviation model 17 5.3 Using the calibration results . 19 5.4 Measuring fibre length . .19 6 Distance calibration methods . 20 6.1 General .20 6.2 External source method 20 6.2.1 Short description and advantage 20 6.2.2 Equipment .20 6.2.3 Calibration of the equipmen
23、t . .21 6.2.4 Measurement procedure . 22 6.2.5 Calculations and results . .23 6.2.6 Uncertainties . .24 6.3 Concatenated fibre method . .25 6.3.1 Short description and advantages . 25 6.3.2 Equipment .25 6.3.3 Measurement procedures. .27 6.3.4 Calculations and results . .27 6.3.5 Uncertainties . .28
24、 6.4 Recirculating delay line method. 29 6.4.1 Short description and advantage 29 6.4.2 Equipment .29 6.4.3 Measurement procedure . 31 6.4.4 Calculations and results . .31 6.4.5 Uncertainties . .32 7 Loss calibration General . 33 7.1 General .33 7.2 Determination of the displayed power level F 33 7.
25、3 Selection of an appropriate reference loss Aref . .34 7.4 Development of a test plan . .35 7.5 Polarization dependence.37 7.6 Calculation of the calibration results38 7.7 Using the calibration results . 38 8 Loss calibration methods 38 BS EN 61746-1:201161746-1 IEC:2009(E) 3 8.1 General .38 8.2 Fi
26、bre standard method. .39 8.2.1 Short description and advantage 39 8.2.2 Equipment .39 8.2.3 Measurement procedure . 40 8.2.4 Calculations and results . .41 8.2.5 Uncertainties . .41 8.3 External source method (see Figure 16).42 8.3.1 Short description and advantage 42 8.3.2 Equipment .42 8.3.3 Calib
27、ration of the reference loss.43 8.3.4 Measurement procedure . 44 8.3.5 Calculations and results . .45 8.3.6 Uncertainties . .45 8.4 Splice simulator method46 8.4.1 Short description and advantage 46 8.4.2 Equipment .46 8.4.3 Procedure. .47 8.4.4 Calculations and results . .49 8.4.5 Uncertainties . .
28、49 8.5 Power reduction method .50 8.5.1 Short description and advantage 50 8.5.2 Equipment .51 8.5.3 Measurement procedure . 52 8.5.4 Calculations and results . .53 8.5.5 Uncertainties . .53 9 Reflectance calibration. .54 9.1 Objective .54 9.2 Reflectance measurements (see Figure 23) 54 9.3 Use of t
29、he backscatter parameter, K . .54 9.4 Range of reflectance measurement.55 9.5 Development of a test plan . .56 9.6 Equipment . .57 9.7 Measurement procedure .58 9.7.1 Preparation58 9.7.2 Taking reflectance measurements. 58 9.7.3 Calculation and results.58 9.7.4 Uncertainties . .58 Annex A (normative
30、) Recirculating delay line for distance calibration . .60 Annex B (normative) Optical fibre standard for loss calibration. 64 Annex C (normative) Standard splice simulator for loss calibration.68 Annex D (normative) Mathematical basis . 72 Annex E (normative) Reflectance standard . 75 Annex F (norma
31、tive) Simple version of reflectance standard 81 Annex G (informative) OTDR basis: Backscatter theory Reflectance measurements using an OTDR Determination of fibre backscatter parameter . 85 Bibliography . 90 BS EN 61746-1:2011 4 61746-1 IEC:2009(E) Figure 1 Definition of attenuation dead zone 10 Fig
32、ure 2 Representation of the location deviation L(L)18 Figure 3 Equipment for calibration of the distance scale External source method . .21 Figure 4 Set-up for calibrating the system insertion delay. .22 Figure 5 Concatenated fibres used for calibration of the distance scale. . 26 Figure 6 Distance
33、calibration with a recirculating delay line .30 Figure 7 OTDR trace produced by recirculating delay line . 30 Figure 8 Determining the reference level and the displayed power level . 34 Figure 9 Measurement of the OTDR loss samples . 35 Figure 10 Region A, the recommended region for loss measurement
34、 samples . .36 Figure 11 Possible placement of sample points within region A . .36 Figure 12 External source method for testing the polarization dependence of the OTDR . 37 Figure 13 Reflection method for testing the polarization dependence of the OTDR . 37 Figure 14 Loss calibration with a fibre st
35、andard 39 Figure 15 Placing the beginning of section D1outside the attenuation dead zone. 40 Figure 16 Loss calibration with the external source method.43 Figure 17 Location and measurements for external source method . 44 Figure 18 Set-up for loss calibration with splice simulator . 46 Figure 19 OT
36、DR display with splice simulator . 47 Figure 20 Measurement of the splice loss . .48 Figure 21 Loss calibration with “fibre-end“ variant of the power reduction method . . 51 Figure 22 Loss calibration with “long-fibre“ variant of the power reduction method. .52 Figure 23 Parameters involved in refle
37、ctance measurements . 54 Figure 24 The same reflectance at the end of three fibres with different values of the backscatter parameter shows different pulse amplitudes 55 Figure 25 Maximum and minimum values for the pulse amplitude, F .56 Figure 26 Range of reflectance measurement. 56 Figure 27 Deter
38、mining the default displayed power level and the default location . 57 Figure 28 Set-up for reflectance calibration58 Figure A.1 Recirculating delay line. .60 Figure A.2 Measurement set-up for loop transit time Tb . .61 Figure A.3 Calibration set-up for lead-in transit time Ta62 Figure B.1 Determina
39、tion of a highly linear power range. .65 Figure B.2 Testing the longitudinal backscatter uniformity of the fibre standard .66 Figure C.1 Splice simulator and idealized OTDR signature68 Figure C.2 Determination of the reference loss Aref . 70 Figure E.1 Reflectance standard description and trace.75 F
40、igure E.2 Calibration set up and reference points for calibration .78 Figure F.1 Reflectance standard description and trace.81 Figure F.2 Calibration set up and reference points for calibration .83 Figure G.1 OTDR signals used for determining reflectance .86 Figure G.2 Set-up for measurement of the
41、backscatter coefficient . .88 BS EN 61746-1:201161746-1 IEC:2009(E) 5 Table 1 Attenuation coefficients defining region A.35 BS EN 61746-1:2011 8 61746-1 IEC:2009(E) INTRODUCTION In order for an Optical time-domain reflectometer (OTDR) to qualify as a candidate for complete calibration using this sta
42、ndard, it must be equipped with the following minimum feature set: a) a programmable index of refraction, or equivalent parameter; b) the ability to present a display of a trace representation, with a logarithmic power scale and a linear distance scale; c) two markers/cursors, which display the loss
43、 and distance between any two points on a trace display; d) the ability to measure absolute distance (location) from the OTDRs zero-distance reference; e) the ability to measure the displayed power level relative to a reference level (for example, the clipping level); f) the ability to evaluate the
44、reflectance of a reflective event. BS EN 61746-1:201161746-1 IEC:2009(E) 9 CALIBRATION OF OPTICAL TIME-DOMAIN REFLECTOMETERS (OTDR) Part 1: OTDR for single mode fibres 1 Scope This part of IEC 61746 provides procedures for calibrating single-mode optical time domain reflectometers (OTDR). It only co
45、vers OTDR measurement errors and uncertainties. This standard does not cover correction of the OTDR response. 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
46、, the latest edition of the referenced document (including any amendments) applies. IEC 60793-1-40, Optical fibres Part 1-40: Measurement methods and test procedures Attenuation IEC 60793-2-50, Optical fibres Part 2-50: Product specifications Sectional specification for class B single-mode fibres IS
47、O/IEC 17025, General requirements for the competence of testing and calibration laboratories ITU-T Recommendation G.650.1:2002, Definitions and test methods for linear, deterministic attributes of single-mode fibre and cable ITU-T Recommendation G.650.2:2002, Definitions and test methods for statist
48、ical and non-linear attributes of single-mode fibre and cable 3 Terms, definitions and symbols For the purposes of this document, the following terms, definitions and symbols apply. NOTE For more precise definitions, the references to IEC 60050-731 should be consulted. 3.1 attenuation loss A optical
49、 power decrease in decibels (dB) NOTE If Pin (watts) is the power entering one end of a segment of fibre and Pout (watts) is the power leaving the other end, then the attenuation of the segment is =outin 10log 10 PPA dB (1) IEV 731-01-48, modified BS EN 61746-1:2011 10 61746-1 IEC:2009(E) 3.2 attenuation coefficient attenuation ( 3.1) of a fibre per u
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