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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