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UnderstandingTier1ReferenceMethodsforFiberCertification
RonGroulx ProductSpecialistFlukeNetworksCanada
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Tier1 DefinedByTIATSB140
Tier1:OLTS(OpticalLossTestSet) Measuresthetotalloss,length,andpolarity ofafiberchannel ConformstoTIA568C(TIA52614AandTIA5267)
BudgetLosstestingwithLS/PM;mostcloselysimulatessystemudge oss es g S/ ; os c ose y s u a es sys e Lengthlimitsarerequiredtomitigatemodaldispersion VerifypolarityusingbidirectionaltestingorduplexOLTS
Tier2:OTDR(OpticalTimeDomainReflectometry) Providesevidencethatcableisinstalledwithoutdegrading
events(e.g.,bends,connections,splices) Setsopticalbudgetsforeachindividualevent Identifiessegmentlengths,connectorlocations&losses,
andlosseswithinsegments
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HowtoMeasureTier1Loss
Set reference by measuring optical signal of t t f d (t i l LED
Source Meter
850 nm1300 nm
source on test reference cords (typical LED -20dBm, Laser -8dBm) Plug into the fiber link and run a new Plug into the fiber link, and run a new measurement (test is subtracted from the reference to produce the loss value)
1) Set Reference
Calculate the total optical loss budget of the fiber link to determine pass/fail limit
maximum attenuation of fiber per km850 nm1300 nm
- maximum attenuation of fiber per km- maximum allowable loss per connection- maximum allowable loss per splice
Th diff b t th t t li it d th
Source Meter
2) Connect to Fiber and run test
The difference between the test limit and the loss value is the margin (negative is fail)
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FiberOpticTestLimitsp
Pass/Faillimitsareestablishedaccordingto/ gtwopossiblesetsofcriteria
1. Verify that a link can support an application1. Verifythatalinkcansupportan application PerformanceoftheChannel isdeterminedbytheactive
componentsExample: IEEE 802 3 (1000BASE SX; 10GBASE SR) Example:IEEE802.3(1000BASESX;10GBASESR)
2. Verifythattheinstallationisdoneproperly Generic approach (often accounts for worst case)Genericapproach(oftenaccountsfor worstcase ) Establishlimitsoncharacteristicsofthecomponentsandlink
configuration
Example: TIA568C and TSB140 ISO 11801 and Example:TIA568CandTSB140,ISO11801andIEC147633
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OpticalPowerMeasurements(dBm)
dBm: Expresses a power level relative to 1 milliwatt (mW)dBm:Expressesapowerlevelrelativeto1milliwatt(mW)
Energy level in dBm = 10 Pout1 mW
Resultof0dBm Pout =1mW Positive value P > 1 mW
1 mW
Positivevalue Pout >1mW Negativevalue Pout
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OpticalLossMeasurementUnits(dB)
Black boxPower in: Pin Power out: Pout
Black box
Gain or Loss in dB = 10 PoutP
Lossismeasuredindecibels(dB)Th l ith i f ti f ti t
Pin
Thelogarithmicfunctionofaratiomeasurement Gain:thefunctionyieldsapositive valueL h f i i ld i l Loss:thefunctionyieldsanegative value
Cablingisapassiveelementh l l ! Thepowerratioisalways aloss!
LinkLossisexpressedasapositive number
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SampledBLossValuesp
dBLoss Pout asa %of Ratio%ofPin powerlost Pout/Pin
1 79% 21%
2 63% 37%
3 50% 50% 1/26 2 % % 1/6 25% 75% 1/4
7 20% 80% 1/510 10% 90% 1/1010 10% 90% 1/10
20 1% 99% 1/100
30 0 1% 99 9% 1/100030 0.1% 99.9% 1/1000
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FiberLossMeasurement PrincipleDifference in two power measurements
1. Reference level: light energy arriving at detector
Test Reference CordSource Detector
2. Loss measurement: light energy arriving at detector -20 dBm
Additional TRCTRC
Fiber OpticLink-under-test
Source DetectorAdapter Adapter
Source Detector
3 Loss difference bet een the t o meas rements
-24.2 dBm
3. Loss: difference between the two measurementsLoss = 4.2 dB
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FiberReference OneJumper
Themethodexplainedinthepreviousslideistheessencef h j h d ( ld h d )oftheonejumpermethod(olderMethodB)
RecommendedbyTIA568C(TIA5267&TIA52614A) Advantage: Advantage:
Correctlyyieldsthelossoftwoadaptersandthelinkundertest
Disadvantages: Canonlybeusedwhenadaptersattheendofthelinkundertestmatchthe
adaptertypeinthetester(detector)
To maintain the reference:Tomaintainthereference: Thecouplingorlaunchconditionsmustbekeptidenticalthroughoutthetest
NEVERREMOVETRCFROMTHESOURCE afterthereferenceh b t f b thasbeensetforbestaccuracy
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ReferenceAlternate TwoJumper
Typicallyperformedwheninstallationadapters(patchpanels&outlets) do not match the tester adapters (older Method A)
Set the reference level:Receiving
outlets)donotmatchthetesteradapters(olderMethodA)
Launch TRCSource Detector
Receiving TRC
Measure loss The difference: Link plus ONE connection
Fiber OpticLi k d t tLaunch
TRCReceivingTRC
Link-under-test
Source DetectorAdapter Adapter
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ModifiedTwoJumperp Alternatemethodtodelivertheproperlossmeasurementforthe
linkundertest plus two adapters (older Adapted Method B)Set the reference level:
Receiving
link under testplustwoadapters(olderAdaptedMethodB)
Launch TRCSource Detector
gTRC
Measure loss The difference: Link plus TWO connections
ReceivingFiber Optic
Link under test
Ad t
LaunchTRC
Ad t
ReceivingTRC
Link-under-test
Source DetectorAdapter Adapter
Additional TRC
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ReferenceAlternate ThreeJumper
Idealfortestingpatchcordsg p TypicallyusedforTestingcablerunswhentheConnectors are not matched at both endsConnectorsarenotmatchedatbothends
Launch f
Tail ReferenceReference
CordSource Detector
Reference Cord
Jumper
Reads P1CL1 CL2
CL1 = Loss of connection type 1CL1 Loss of connection type 1CL2 = Loss of connection type 2
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MeasuringThreeJumperMethod
L h T ilFib O ti
Link-under-test Loss Measurement Launch
Reference Cord
TailReference
Cord
Fiber OpticLink-under-test
Source Detector
CL4
Source Detector
Reads P2CL3
ThelossmeasurementiscalculatedasP2 P1 Measuredloss=LossFiber +(CL3CL1)+(CL4CL2)Fiber 3 1 4 2 IfCL1 andCL2 arezero,thenthemeasuredlosswillbecorrect
ButCL1 andCL2 areNOT zero
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ThreeJumperReferenceIsNotIdeal for 2 Panel LinksIdealfor2PanelLinks
QualityoftheTRCcordsbecomescritical Testingwithcordsthatareworseprovideamorelenientlimit
T ti ith d th t b tt id t h li it Testingwithcordsthatarebetterprovideatougherlimit
Thisiscounterintuitivebutcancreaterealproblems
ComparedtotheOneJumpermethodthismethodunderestimatesthelinklossbyroughly0.2dBforMM and 0 4 dB for SMMMand0.4 dBforSM
Inconclusion:Useonejumper(withcorrectadapterth d t t ) difi d t j f li konthedetector)ormodifiedtwojumperforlinks
withtwoormoredissimilarconnections
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ReviewoftheOnejumperMethod
Set the reference: Launch
MethodSet the reference: Launch
Reference CordSource Detector
LaunchReference
FiberLink-under-test
Measure loss:Additional TRC
CL
Cord
CL
Source DetectorTRC
CL3 CL4
Keyissue:Detectoradapter=adapterofLinkundertest Measured loss: Loss + CL + CL Measuredloss:LossFiber +CL3 +CL4 NOsystematicerrorfromconnections
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DualfiberLossMeasurements
PolarityTest Ensuresfiberistestedintheproperdirectioninonestep
TR RC
TRRC
InOut InOut
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OneJumperReferencewithDualfiber AdaptersDual fiberAdapters
Setreferencewithtwoduplexcords(exampleh diff )shownusesdifferentoutputportconnector)LC LC
LC
LCLC
LC
InOut
SC
InOut
SC
LC AdapterMain Unit Remote Unitp
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HowtoDisconnectDualfiberOneJumper ReferenceOne JumperReference
Connecttothelinkundertest(LUT)( )
LC LCTo LUT Remote To LUT Main
LCLC
SC
LCLCSC
InOut InOutLC Adapter
Do not move
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DualfiberLossMeasurement
Lossmeasurementwithtwoduplexcords
LCLC
LCLC
IO t
LCSC
IO t
SCLC
InOutInOut
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Mandrel ControlMultimodeLaunch ConditionsLaunchConditions
LEDlightsourcethatpassestheModalPowerDi ib i (PMD) ifi iDistribution(PMD)specification
Controltheoverfilllaunchconditionwiththeuseofamandrel
Diameterandnumberofwrapsdeterminetheeffectofthemandrel
Desiredresult:Strip out the higher orderStripoutthehigherordermodesoflighttomatchVCSELsource
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Questions?
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