UnderstandingTier1ReferenceMethodsforFiberCertification

RonGroulx ProductSpecialistFlukeNetworksCanada

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

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)

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

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

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

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

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

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

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

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

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

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

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

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

DualfiberLossMeasurements

PolarityTest Ensuresfiberistestedintheproperdirectioninonestep

TR RC

TRRC

InOut InOut

OneJumperReferencewithDualfiber AdaptersDual fiberAdapters

Setreferencewithtwoduplexcords(exampleh diff )shownusesdifferentoutputportconnector)LC LC

LC

LCLC

LC

InOut

SC

InOut

SC

LC AdapterMain Unit Remote Unitp

HowtoDisconnectDualfiberOneJumper ReferenceOne JumperReference

Connecttothelinkundertest(LUT)( )

LC LCTo LUT Remote To LUT Main

LCLC

SC

LCLCSC

InOut InOutLC Adapter

Do not move

DualfiberLossMeasurement

Lossmeasurementwithtwoduplexcords

LCLC

LCLC

IO t

LCSC

IO t

SCLC

InOutInOut

Mandrel ControlMultimodeLaunch ConditionsLaunchConditions

LEDlightsourcethatpassestheModalPowerDi ib i (PMD) ifi iDistribution(PMD)specification

Controltheoverfilllaunchconditionwiththeuseofamandrel

Diameterandnumberofwrapsdeterminetheeffectofthemandrel

Desiredresult:Strip out the higher orderStripoutthehigherordermodesoflighttomatchVCSELsource

Questions?

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