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7、Optical Time-Domain Reflectometers (OTDRs) Standard should be submitted to TIA. (From Standards Proposal No. 3-0032, formulated under the cognizance of the TIA FO-6.1 Subcommittee on Fiber Optic Test, Measurement, and Inspection Instrumentation.) Published by TELECOMMUNICATIONS INDUSTRY ASSOCIATION
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17、LIABILITY OR OTHERWISE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. THE FOREGOING NEGATION OF DAMAGES IS A FUNDAMENTAL ELEMENT OF THE USE OF THE CONTENTS HEREOF, AND THESE CONTENTS WOULD NOT BE PUBLISHED BY TIA WITHOUT SUCH LIMITATIONS. 61746 O IEC TlA-455-226 CONTENTS 1 General 1 1 .I Scope
18、 1 1.2 Normative references . 1 2 Definitions 2 3 Calibration test requirements 8 3.1 Preparation . .8 3.2 Test conditions 8 3.3 Traceability 9 Distance calibration - General 9 4.1 Location error model 9 4.2 Using the calibration results . 11 4.3 Measuring fibre length . 12 Distance calibration meth
19、ods 12 5.1 External source method 12 5.1.2 Equipment 13 5.1.3 Measurement procedure 14 5.1.4 Calculations and results 15 5.1.5 Uncertainties 16 5.2 Concatenated fibre method 17 5.2.1 Short description and advantages 17 5.2.2 Equipment 18 5.2.3 Measurement procedures 19 5.2.4 Calculations and results
20、 20 5.2.5 Uncertainties 20 5.3 Recirculating delay line me 22 5.3.1 Short description and advantage 22 5.3.2 Equipment 22 5.3.3 Measurement procedure 23 5.3.4 Calculations and results 24 5.3.5 U ncertaintie 24 6 Loss calibration - Genera 26 6.1 Determination of the displayed power level F 26 6.2 Sel
21、ection of an appropriate reference loss A,f . 27 6.3 Development of a test plan 28 6.4 Polarization dependence 30 6.5 Calculation of the calibration results . 31 6.6 Using the calibration results . 32 Loss calibration methods 32 7.1 Loss calibration with fibre standard 32 4 5 5.1 .I Short descriptio
22、n and advantage 12 7 61 746 O IEC TlA-455-226 7.1.1 Short description and advantage . 32 7.1.2 Equipment . . 32 7.1.3 Measurement procedure .34 7.1.4 Calculations and results . . 35 7.1.5 Uncertainties .35 7.2 External source method . . 36 7.2.1 Short description and advantage . 36 7.2.2 Equipment .
23、 . 36 7.2.3 Measurement procedure . 37 7.2.4 Calculations and results . . 39 7.2.5 Uncertainties . 39 7.3 Splice simulator method . . 40 7.3.1 Short description and advantage . 40 7.3.2 Equipment . . 41 7.3.3 Procedure .42 7.3.4 Calculations and results . .44 7.3.5 Uncertainties .44 7.4 Power reduct
24、ion method .45 7.4.1 Short description and advantage .45 7.4.2 Equipment . .46 7.4.3 Measurement procedure . .47 7.4.4 Calculations and results .48 7.4.5 Uncertainties . . 48 8 Reflectance calibration . 50 9 Documentation . 50 9.1 Measurement data and uncertainties 50 9.2 Test conditions 50 51 A.l C
25、onstruction . 51 A.2 Calibration 51 A.2.1 Measurement equipment . 52 A.2.2 Procedure . 52 A.3 Uncertainties 53 A.4 Documentation . 54 55 B.l Fibre requirements . 55 B.2 Suitability check of ibre 55 B.2.1 Linearity test of the OTDR power scale . 55 Annex A (normative) Recirculating delay line for dis
26、tance calibration Annex B (normative) Optical fibre standard for loss calibration . . B.2.2 Directional dependence of the backscatter loss 56 B.2.3 Longitudinal attenuation uniformity of the fibre 56 B.4 Recalibration of the optical fibre standard . 58 B.5 Uncertainty of the fibre standard 58 B.6 Do
27、cumentation 58 59 B.3 Preparation and calibration of the fibre standard 57 Annex C (normative) Standard splice simulator for loss calibration II 61746 O IEC TlA-455-226 C.l Structure . 59 C.l . 1 Description 59 C.1.2 Splice loss analysis 59 C.2 Preparation of the standard splice simulator . 60 C.3 C
28、alibration procedure . 60 C.4 Uncertainties . 61 C.5 Documentation 62 Annex D (informative) Mathematical basis 63 D.l Deviations . 63 D.2 Uncertainties type A . 63 D.3 Uncertainties type B . 64 D.4 Accumulation of uncertainties 65 D.5 Reporting . 66 D.l Deviations . 63 D.2 Uncertainties type A . 63
29、D.3 Uncertainties type B . 64 D.4 Accumulation of uncertainties 65 D.5 Reporting . 66 Figure 1 . Definition of attenuation dead zone . 3 Figure 2 . Representation of the location error AL) . 10 Figure 3 - Equipment for calibration of the distance scale - External source method 13 Figure 4 . Set-up f
30、or calibrating the system insertion delay 14 Figure 5 . Concatenated fibres used for calibration of the distance scale . 18 Figure 6 . Distance calibration with a recirculating delay line . 22 Figure 7 . OTDR trace produced by recirculating delay line . 23 Figure 8 . Determining the reference level
31、and the displayed power level 27 Figure 9 . Measurement of the OTDR loss samples 28 Figure 1 O . Region A, the recommended region for loss measurement samples 29 Figure 11 . Possible placement of sample points within region A Figure 12 . External source method for testing the polarization d Figure 1
32、3 . Reflection method for testing the polarization dependence of the OTDR 31 Figure 14 . Loss calibration with a fibre standard 33 Figure 15 . Placing the beginning of section Dl outside the attenuation dead zone 34 37 Figure 17 . Location and measurements for external source method . 38 Figure 18 .
33、 Set-up for loss calibration with splice simulator . 41 Figure 19 . OTDR display with splice simulator (the smaller circle represents the OTDR response to the reference loss) 42 Figure 20 . Measurement of the splice loss . 43 Figure 21 . Loss calibration with “fibre-end“ variant of the power reducti
34、on method 47 Figure 16 . Loss calibration with the external source method . III 61 746 O IEC TlA-455-226 Figure 22 . Loss calibration with “long-fibre“ variant of the power reduction method . 47 Figure A.l . Recirculating delay line 51 Figure A.2 . Measurement set-up for loop transit time Tb . 52 53
35、 Figure B.l . Determination of a highly linear power range 56 Figure B.2 . Testing the longitudinal backscatter uniformity of the fibre standard . 57 Figure C.l . Splice simulator and idealized OTDR signature 59 Figure C.2 . Determination of the reference loss Aref 61 Figure D.l . Deviation and unce
36、rtainty type B, and how to replace both by an appropriately larger uncertainty 65 Table 1 . Attenuation coefficients defining region A . 28 Figure A.3 . Calibration set up for lead-in transit time Ta iv 61746 O IEC TIA-455-226 INTERNATIONAL ELECTROTECHNICAL COMMISSION FDIS 86/XX/F D I S CALIBRATION
37、OF OPTICAL TIME-DOMAIN REF L E CTOM ETE RS (OTD Rs) Report on voting 86/XX/ RV D FOREWORD 1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising all national electrotechnical committees (IEC National Committees). The object of the IEC is to
38、promote international co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and in addition to other activities, the IEC publishes International Standards. Their preparation is entrusted to technical committees; any IEC National Committee inter
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42、national unification, IEC National Committees undertake to apply IEC International Standards transparently to the maximum extent possible in their national and regional standards. Any divergence between the IEC Standard and the corresponding national or regional standard shall be clearly indicated i
43、n the latter. 5) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any equipment declared to be in conformity with one of its standards. 6) Attention is drawn to the possibility that some of the elements of this International Standard may be the su
44、bject of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights. International Standard IEC 61 746 has been prepared by IEC technical committee 86: Fibre optics. The text of this standard is based on the following documents: Full information on the voting
45、for the approval of this standard can be found in the report on voting indicated in the above table. This publication has been drafted in accordance with the ISO/IEC Directives, Part 3. Annexes A, B and C form an integral part of this standard. Annex D is for information only. V 61 746 O IEC TlA-455
46、-226 The committee has decided that the contents of this publication will remain unchanged until 2002. At this date, the publication will be reconfirmed; withdrawn; amended. replaced by a revised edition, or vi 61746 O IEC TlA-455-226 CALIBRATION OF OPTICAL TIME-DOMAIN REF L E CTOM ETE RS (OTD Rs) 1
47、 General 1.1 Scope This International Standard provides procedures for calibrating single-mode optical time domain reflectometers (OTDRs). It only covers OTDR measurement errors and uncertainties. It does not cover correction of the OTDR response. In order for an OTDR to qualify as a candidate for c
48、omplete calibration using this standard, it is to be equipped with the following minimum feature set: a programmable index of refraction, or equivalent parameter; the ability to present a display of a trace representation, with a logarithmic power scale and a linear distance scale; two markers/curso
49、rs, which display the loss and distance between any two points on a trace display; the ability to measure absolute distance (location) from the OTDRs zero-distance reference; the ability to measure the displayed power level relative to a reference level (for example, the clipping level). 1.2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parti
