1、 TIA/EIASTANDARDFOTP-8Measurement of Splice or ConnectorLoss and Reflectance Using an OTDRTIA/EIA-455-8MAY 2000TELECOMMUNICATIONS INDUSTRY ASSOCIATIONRepresenting the telecommunications industry inassociation with the Electronic Industries Alliance ANSI/TIA/EIA-455-8-2000Approved: April 25, 2000TIA/
2、EIA-455-8Copyright Telecommunications Industry Association Provided by IHS under license with EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NOTICETIA/EIA Engineering Standards and Publications are designed to serve the public interestthrough eliminating misund
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6、andardor Publication.This Standard does not purport to address all safety problems associated with its use or allapplicable regulatory requirements. It is the responsibility of the user of this Standard toestablish appropriate safety and health practices and to determine the applicability of regulat
7、orylimitations before its use.(From Standards Proposal No. 2828-A and 2828-A-1, formulated under the cognizance of the TIAFO-6.6 Subcommittee on Fibers and Materials.)Published byTELECOMMUNICATIONS INDUSTRY ASSOCIATION 2000Standards and Technology Department2500 Wilson BoulevardArlington, VA 22201PR
8、ICE: Please refer to current Catalog ofEIA ELECTRONIC INDUSTRIES ALLIANCE STANDARDS and ENGINEERING PUBLICATIONS or call Global Engineering Documents, USA and Canada(1-800-854-7179) International (303-397-7956)All rights reservedPrinted in U.S.A.Copyright Telecommunications Industry Association Prov
9、ided by IHS under license with EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-PLEASE!DONT VIOLATETHELAW!This document is copyrighted by the TIA and may not be reproduced withoutpermission.Organizations may obtain permission to reproduce a limited number of copi
10、esthrough entering into a license agreement. For information, contact:Global Engineering Documents15 Inverness Way EastEnglewood, CO 80112-5704 or callU.S.A. and Canada 1-800-854-7179, International (303) 397-7956Copyright Telecommunications Industry Association Provided by IHS under license with EI
11、ANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-Copyright Telecommunications Industry Association Provided by IHS under license with EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TIA/EIA-455-8iFOTP-8Measurement of splice or
12、connectorloss and reflectance using an OTDRContentsPageSectionContents iForeword iii1 Introduction 12 Normative References . 13 Apparatus . 24 Sampling and specimens . 25 Procedure 26 Calculation or interpretation of results 67 Documentation 78 Specification information . 8Figure1 Schematic OTDR Tra
13、ce for a fiber lengthcontaining various types of discontinuities 42 Schematic OTDR close-up trace fora reflective splice or connector . 4AnnexA Features of an OTDR . 9B Comparison between FOTP-8and IEC and ITU requirements 12Copyright Telecommunications Industry Association Provided by IHS under lic
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15、-,-,-TIA/EIA-455-8iiiFOTP-8Measurement of splice or connectorloss and reflectance using an OTDRForeword(This foreword is informative and is not a part of this standard.)This document comes from TIA Standards Proposal No. 2828A, formulated under the cognizanceof TIA FO-6.3, Subcommittee on Fiber Opti
16、c Interconnecting Devices. It has not been previouslypublished.This FOTP is part of the series of test procedures included within Recommended StandardTIA/EIA-455.There are two Annexes, one normative, the other informative.Key words: splice, connector, reflectance, OTDRCopyright Telecommunications In
17、dustry Association Provided by IHS under license with EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TIA/EIA-455-8ivThis page left blank.Copyright Telecommunications Industry Association Provided by IHS under license with EIANot for ResaleNo reproduction or net
18、working permitted without license from IHS-,-,-TIA/EIA-455-81FOTP-8Measurement of splice or connectorloss and reflectance using an OTDR1 Introduction1.1 IntentThis procedure describes the use of an optical time-domain reflectometer (OTDR) to indirectlymeasure the loss and reflectance of a splice or
19、connector.1.2 Other methodsLoss or reflectance measurements may be obtained also by using FOTP-34 or FOTP-107. Thelatter values will be accepted as correct in the event of a dispute.1.3 Trace defectsSome OTDR/fiber combinations appear to give “noisy” traces that may be repeatable for a givenOTDR but
20、 not against other OTDRs with the same fiber. These appear to be related topolarization and coherence effects, and are being studied in FO-6.6. Some OTDR manufacturersoffer noise filters, internal or external to the OTDR, and care shall be taken that these do not mask“true” artifacts of the trace. M
21、oreover, parts of the trace that are noisy due to low signal-to-noiseratio shall not be used.2 Normative referencesFOTP-34 (TIA/EIA/-455-34A) Interconnection device insertion loss testFOTP-57 (TIA/EIA-455-57B) Optical fiber end preparation and examinationFOTP-60 (TIA/EIA-455-60A) Measurement of fibe
22、r or cable length using an OTDRFOTP-77 (EIA/TIA-455-77) Fabricating and qualifying a higher-order mode filter forsingle-mode fiber measurementsCopyright Telecommunications Industry Association Provided by IHS under license with EIANot for ResaleNo reproduction or networking permitted without license
23、 from IHS-,-,-TIA/EIA-455-82FOTP-78 (EIA/TIA-455-78A) Spectral attenuation cutback measurement for single-modefibersFOTP-107 (EIA/TIA-455-107A) Return loss for fiber optic componentsIEC 86(Secretariat)49, revised Calibration of optical time-domain reflectometers3 ApparatusSee Annex A.4 Sampling and
24、specimens4.1 Specimens are one or more splices or connectors within a fiber on a reel, within a cable,or under a condition specified in the Detail Specification. Care should be taken so that thewinding does not introduce artificial loss or reflection. The measurement may be performed in thefactory o
25、r in the field, upon either single or concatenated sections.4.2 Prepare a flat endface at the input end of the specimen as described in FOTP-57, or asotherwise directed by instructions from the OTDRs manufacturer.5 Procedure5.1 Calibration verificationFor U.S. Military applications, this step shall
26、be performed daily (or as otherwise required) prior tomaking any specimen measurements. In all other operations, recalibration should occur once peryear or per other duration depending upon usage, required accuracy, OTDR manufacturerrecommendations, or as required by a Detail Specification.Perform l
27、oss and reflectance measurements on splices or connectors that bracket the desiredmeasurement ranges, using the procedures of the remainder of clause 5 with an OTDR of knownaccuracy, or using FOTP-34 or FOTP-107, as appropriate. If necessary, perform severalmeasurements to reduce measurement variabi
28、lity by statistical analysis.Copyright Telecommunications Industry Association Provided by IHS under license with EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TIA/EIA-455-83Determine the calibration state of the current OTDR by remeasuring the same splices or
29、connectors. If the difference between the measured values exceeds a predetermined limit (suchas 0.05 dB in loss and 0.5 dB in reflectance) based on the intended use of the component,recalibrate and reverify the OTDR.An extensive calibration procedure, not specifically addressing discontinuities, is
30、given in the IECdocument referred to in clause 2. A simpler procedure, suitable for daily calibration, can be doneusing well-characterized loss and reflection artifacts.5.2 Connect to OTDRConnect the fiber containing the specimen(s) to either the instrument or to one end of thedead-zone fiber (if us
31、ed). Connect the other end of the dead-zone fiber (if used) to theinstrument.5.3 Group indexIf accurate distances to the splices or connectors are to be recorded, the group index1of the fiberor cable is required. If this value is not known, use FOTP-60 to determine it.5.4 OTDR parametersEnter OTDR p
32、arameters such as source wavelength, pulse duration, length range, and signalaveraging into the instrument, along with the fiber or cable group index (if required by 5.3). Thevalues of some of these parameters may be preset in the instrument.5.5 Display signalAdjust the instrument to display a backs
33、catter signal from the specimen. It may be advantageousto begin with coarse vertical and horizontal scaling to maximize the length displayed. An exampleis given in Figure 1.1Other terms used: refractive index (common but erroneous), group delay index, effective group index,group velocity index, fibe
34、r indexCopyright Telecommunications Industry Association Provided by IHS under license with EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TIA/EIA-455-8OTDR Signal(dB)P2HP1z1LDistance zOTDR Signal(dB)noiseinputreflectionend-facereflectionreflection,without loss
35、reflection,with lossapparent loss,no reflectionapparent gain,no reflectionFigure 1Schematic OTDR trace for a fiber length containing various types of discontinuitiesSchematic OTDR close-up tCopyright Telecommunications Industry Association Provided by IHS under license with EIANot for ResaleNo repro
36、duction or networking permitted without license from IHS4Distance zz4z3P4P3Figure 2race for a reflective splice or connector-,-,-TIA/EIA-455-855.6 Adjust display this may be done by attenuating the signal with an OTDR control, by an in-linevariable attenuator, or by introducing a loop prior to the s
37、plice or connector. (The loop should bepositioned a distance prior to the reflection at least equal to a pulse duration or an attenuationdead-zone as given by the manufacturer. This ensures that the reading for G011still lies on the fiberbaseline.) If the value of the heightG03G01G01=21(in dB)is con
38、stant as the attenuation is varied, then saturation is not occurring.5.6.3 Place the same or another cursor at the end of the feature at a point along the linearportion of the fiber following it. Obtain the power level G013and the distance coordinate G023. Thedistance ( )G02G0231 may be several time
39、s the width of the pulse near its peak to avoid thenonlinear tail.5.6.4 Repeat this for another following point of power G014and position G024. The distance()G02G0243 is small enough to minimize any attenuation nonuniformity and large enough so thatnoise is insignificant.5.6.5 (optional) Repeat the
40、procedures of 5.6.3 and 5.6.4 for points G023and G024even furtherfrom G021. This can help to validate the previous measurements.5.7 Other directionRepeat the measurement for a signal launched into the specimen in the opposite direction.5.8 Other wavelengthsIf required by the Detailed Specification,
41、repeat the test at other wavelengths.Copyright Telecommunications Industry Association Provided by IHS under license with EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TIA/EIA-455-865.9 Other pulse widthsIf required by the Detailed Specification, repeat the te
42、st at other pulse widths. This is sometimesuseful to verify a reflectance value.6 Calculations or interpretation of resultsPerform the calculations required in the Detail Specification.6.1 LossAn estimate of the loss (in dB) of the splice or connector is given by()().34134331zzzzPPPPL=(The formula t
43、akes the fiber attenuation between G021and G023into account.) By the conventionused here, a positive loss characterizes a drop in the OTDR trace. A negative value indicates a“false gain“ due to appropriate fiber backscatter differences on either side of the splice orconnector.6.2 2-Point the calcula
44、ted reflectance results need not be averaged. This eliminates effects(such as apparent gain) of length-varying backscatter properties, so that more accurate estimatesresult. Some OTDRs can perform these calculations automatically.7 Documentation7.1 Report the following information with each test:7.1
45、.1 Date of test.7.1.2 Sample or specimen identification.7.1.3 FOTP number.7.1.4 As required by the Detail Specification, the location G02 , loss G06 , reflectance G07 , andreflectance measurement direction for each of the splices and connectors, at the specifiedwavelengths.7.2 United States military
46、 applications require that the following information also be reported foreach test. For other (nonmilitary) applications, this information need not be reported but shall beavailable for review upon request:7.2.1 Test personnel.Copyright Telecommunications Industry Association Provided by IHS under l
47、icense with EIANot for ResaleNo reproduction or networking permitted without license from IHS-,-,-TIA/EIA-455-887.2.2 Dates of last calibration.7.2.3 Splice or connector test sample(s) or specimens, including type and deploymentconditions.7.2.4 OTDR instrument (including make, model and manuals), an
48、d latest calibration date.7.2.5 Pulse duration(s) G04 , number of averages (if applicable), and scale range(s).7.2.6 Test wavelength(s) and spectral width(s) as periodically verified per A.1.7.2.7 Launch conditions.7.2.8 Dead-zone fiber, if any.7.2.9 Method of calculation for the loss and reflectance.7.2.10 Value of fiber backscatter coefficient B assumed.8 Specification informationThe following details shall be specified in the Detail Specification:8.1 FOTP number.8.2 Test wav
