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Fluke Networks, Inc.P.O. Box 777, Everett, WA USA 98206-0777(800) 283-5853 Fax (425) 446-5043

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2011 Fluke Corporation. All rights reserved.Printed in U.S.A. 3/2011 3481323B

Optical Fiber Cabling or Data Communication

Test and Troubleshooting Quick-Reerence Guide

N E T W O R K S U P E R V I S I O N

Your authorized Fluke Networks distributor

Download the extended vers ion o this guide, which includes additionaloptical-ber theory, test, and certication inormation at:

www.ukenetworks.com/FiberHandbook

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1

Table o Contents

1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

2. Fiber Verifcation Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

3. How to Certiy Optical Fiber Cabling with OLTS and LSPM . . . . . . . . . . . . . . . . . . . . 4

4. How to Certiy Optical Fiber Cabling with an OTDR . . . . . . . . . . . . . . . . . . . . . . . . . 10

Cablecerticationteststrategy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

5. Common Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

6. End-Face Inspection and Cleaning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Inspection. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Cleaning. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

7. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

8. Glossary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

9. Appendix FlukeNetworksFiberTestandTroubleshootingInstruments . . . 21

N E T W O R K S U P E R V I S I O N

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32

1. IntroductionAs fber links support higher speed network bandwidths with increasingly stringent

requirements, it is becoming all the more important to ensure that your backbone links meet

tightening loss standards. The need or higher data transmission capacity continues to growas network applications grow and expand. These higher transmission speeds demand cabling

that delivers higher bandwidth support. This test and troubleshooting guide outlines cabling

perormance requirements, feld testing, certifcation and troubleshooting techniques and

instruments to ensure that the installed optical fber cabling supports the high data rate

applications such as 1 and 10 Gigabit per second (Gbps) Ethernet, Fibre Channel and the

anticipated 40 and 100 Gbps Ethernet applications.

A local area network (LAN) or an enterprise (premises) network connects users up to a

distance o 5 km. It encompasses the intra-building connectivity as well as inter-building

cabling or the campus cabling. Optical fber cabling is primarily used or longer distance,higher bandwidth connectivity while twisted pair copper cabling typically provides the

connection to the end-user or to the edge devices. This copper cabling can support network

connectivity to a distance o 100 meters (328 eet). Optical fber cabling is the preerred

medium or distances beyond 100 meters such as riser cables in the building.

This guide reviews best practices or test and troubleshooting methods as well as the test

tools to ensure that installed optical fber cabling provides the transmission capability to

reliably support LAN or enterprise network applications. Certifcation, or the process o

testing the transmission perormance o an installed cabling system to a specifed standard,

ensures a quality installation. It also provides ofcial documentation and proo that therequirements set by various standards committees are ully satisfed.

Optical fber is a reliable and cost eective transmission medium, but due to the need or

precise alignment o very small fbers, problems ranging rom end-ace contamination to

excess modal dispersion can cause ailures to occur. Regardless, narrowing down the

source(s) o ailure is oten a time-consuming and resource-intensive task.

For this reason, Fluke Networks has created an enterprise-ocused fber troubleshooting guide

to assist in ensuring: 1) proper assessment o cable installation quality, and 2) efcient

troubleshooting to reduce the time spent identiying the root cause o a problem beoretaking corrective action to fx it. Note that this guide does not address issues that are

especially germane to the long-haul telecommunications application o the

fber optic technology.

2. Fiber Veriication TestingFiber verication testing (including end-ace inspection and cleaning) should be practiced

continually as standard operating procedure. Throughout the cable installation process and

prior to certication, loss o cabling segments should be measured to ensure the

quality o the installation workmanship. This type o a test is normally accomplished with

a Light Source and Power Meter (LSPM) test set. Fiber verication test tools are typically

less expensive tools; they can also eectively be used to troubleshoot troublesome links.

A quick inspection o the end-to-end link loss may provide the indication whether or not

the optical ber cable is suspect or whether other network unctions are the cause o the

detected malunction.

An LSPM determines the total light loss along a ber link by using a known light source

at one end o the ber and a power meter at the other. But beore the test can be done,

as described earlier, a reerence power level rom the source is measured and recorded to

set a baseline or the power loss calculation. Ater this reerence is established, the meter

and source are plugged into the opposite sides o the ber link to be tested. The source

emits a continuous wave at the selected wavelength. On the distant end, the power meter

measures the level o optical power it is receiving and compares it to the reerence power

level to calculate the total amount o light loss (Figure 1).Ifthistotallossiswithinthe

specied parameters or the link-under-test, the test passes.

A loss budget should be well established and used as a benchmark during cabling

installation.Ifthistypeofvericationtestingisperformedduringinstallation,itcanbe

expected that yield will increase and certication testing will go smoother.

LSPM test sets have historically been more dicult to use, requiring manual calculations

and subjective interpretation by an experienced technician. However, newer instruments

have eliminated time-consuming loss calculations by automating the process o comparing

power measurements versus set reerences.

Figure 1 Conducting an LSPM test

Fiber under test

*Mandrelusedonlyfor850/1300 nm testing

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While convenient, basic verication o end-to-end loss using an LSPM set does not speciy

where the trouble areas are, making ailures dicult to locate. Even in instances where

the loss is within a specied threshold, the LSPM set does not provide any warning or

indicationofwhereadefectorproblemmaybelocated.Inotherwords,althoughan

entire link may pass, it is possible that individual splices or connections within it may ail

industry specications, creating a potential problem in the uture during adds, moves, or

changes where multiple dirty connectors can potentially be grouped together to result in

a ailure. An Optical Time Domain Refectometer (OTDR) is the proper test tool to pinpoint

locations (connections) displaying a high loss or refectance.

3. How to Certiy Optical Fiber Cablingwith OLTS and LSPM

IndustrystandardsrequiretestingwithanLSPMorOpticalLossTestSet(OLTS)tocertify

that the loss o each link meets perormance standards. This is reerred to as basic or

Tier 1 Certication.

Itisadouble-endedtestwhichproducesanabsolutelossmeasurementwhichisthen

compared with installation cabling standards and/or channel application standards. Fluke

Networks DTX CableAnalyzer and OptiFiber OTDR can be equipped with optional multimode

or singlemode ber test modules that automate most o the test and make basic or Tier 1

certication very easy.

Note that an OTDR also provides loss results or the total link, but this measurement is

based on the refected light energy. The standards demand that the basic certication be

executed with an OLTS or LSPM. These link loss results provided by using a light source on

one end and a light meter at the opposite end are more accurate i properly executed.

The ollowing steps should be ollowed to perorm a basic loss length certication test:

Establish Pass/Fail test limits

Choose a test method and set a reerence

Run the test and save results

Export to LinkWare to manage and archive the test results; LinkWare is Fluke Networks

popular and widely-used ree data management sotware that lets you create printed or

electronic reports

1. Establish Pass/Fail limitsinaccordancetowhatyourcerticationgoalsare.Inthis

example, we will establish limits or the total allowable loss based on an application

standard using the Fluke Networks DTX Series tester equipped with the DTX-MFM2 ber

losstestmodules(formultimode).Ifyouneedtocertifysinglemodeberusethe

DTX-SFM2 modules.

a.Oncethetesteristurnedon,turntherotaryswitchtoSetupandselectInstrument

Settings to input the operator name, job name etc.

b. Select Fiber Loss rom the Setup screen as

shown in Figure 2a. Under this setup screen,

you will choose rom a menu o standards to

select the correct limits. Select the Test Limit

option as shown in Figure 2b. Note that the

selected ber type limits the test limit choices.

Popular ber types are also included in the

instrument menu.

As Figure 2b shows, the same setup screen

allows you to select the Remote End Setup. When

using the DTX Smart Remote equipped with the

ber test module, select Smart Remote as we

havedoneinthisexample.Inthismode,the

tester automatically measures the length o the

link-under-test.

Lastly, this screen provides the option to tell the

tester whether you need to test the link-under-test

inbothdirections.Ifthisisthecase,remember

never to disconnect the test reerence cord (TRC)

rom the test modules; always swap the TRC at the

connection with the link-under-test.

2.Choose a reerence method and set a

reerence. As described earlier, setting a

reerence is a critical aspect o a loss test to obtain

accurate test results. The power meter and light

source are connected together and the power level

is measured by the light meter to establish the

reerence or loss calculations.

The steps or setting a reerence are as ollows:

Step A. Turn the rotary switch to Special

Functions and choose Set Reerence

(Figure 2c)

Step B. Now press Enter and connect the TRCs

between main and remote as shown on

the screen and press test to make the

reerence measurement.

Figure 2a

Figure 2c

Figure 2b

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With the DTX Series in Smart Remote setup, we

are going to test the two bers that make up

the transmission link in one test. Each ber test

module is equipped with a light source and light

meter.Inthesetup,wewillusetwoduplexTRCs.

One ber will connect the Output (light source)

atthemainunittotheInput(lightmeter)atthe

remote unit. The second connects the Output at

the remote unit to the input at the main unit.

Special Note: The DTX TRCs use the ollowing

convention in order to quickly make connections

and veriy the polarity o the link-under-test: the

light enters the cord at the red boot and leaves

the TRC at the black boot. So, one end o a TRC

has a red boot and at the other end o that same cord is a black boot. The light travels

rom red to black. The DTX screen display shows the boot color (Figure 2d).

Figure 2e shows a schematic representation o this reerence setup. This gure uses

a dierent color or the two duplex cords. These colors do not relate to the real cords

but were chosen to add clarity to the gure. The yellow cord connects the Output (light

source)ofthemainunitsbermoduletotheInput(lightmeter)oftheremoteunit.

One o the yellow cords is not connected in the reerence setting. One o the darker

colored cords makes the connection in the opposite direction. Figure 2e also shows the

location o the mandrel near the end with the red boot that is to be connected to the

light source. The duplex cords have one longer leg with the red boot. Ater this leg has

been wrapped around the mandrel, the lengths o both cords in the duplex arrangement

are equal.

The DTX ber modules Output ports are always SC connectors. The removable adapters

fortheInputportsarechosentomatchtheendconnectorsofthelink-under-test.The

example in Figure 2e depicts the example in which the link-under-test is equipped with

LC connectors.

Figure 2e Schematic representation o setting the reerence with duplex TRCs or a link-under-test

ending with LC connectors. The ring near the red boot indicates the location o the mandrel

(or multimode fber).

Step C. Ater the tester measures the reerencepower level, it displays these values as

shown in Figure 2.Ifyourreference

values are acceptable, press the F2

sotkey to store these values and to

proceed with link certication.

Acceptable Reerence Values*

Model62.5 m

Multimode

50 m

Multimode

9 m

Singlemode

MFM, MFM2 -20 dBm -24.5 dBm N/A

SFM, SFM2,

GFM, GFM2-8 dBm -8 dBm -20 8m

*nominal level

Step D. Now disconnect your TRCs at the Input

ports only and create the connection

that is shown on the screen (Figure 2g).

Disconnect the black boots rom the input

ports and connect the unused ends with

the black boots in the duplex cord set to

the adapter on the input port o the unit

to which the duplex mate has been con-

nected. Now you have separated the main

and remote units so that you can connect

a unit at each end o the optical ber link

to be tested.

Figure 2d

Figure 2g

Figure 2f

Main to Remote

Main Unit

Out In Out In

Remote UnitLC Adapters

Remote to Main

LC

LC

LC

LC

LC

SC SC

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Guidelines or setting a reerence

Usehigh-qualityTRCs

CleanTRCendsbeforeyousetthereference

Letthetesterwarmuptoasteady-stateinternaltemperature

(about 10 min. with ambient temp and storage temp dierence o

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4. How to Certiy Optical Fiber Cablingwith an OTDR

TIA568C.0TSB140andISO14763-3recommendOTDRtestingasacomplementarytest

to ensure that the quality o ber installations meets component specications. The

standardsdonotdesignatePass/Faillimitsforthistest.Itisrecommendedthatgeneric

cabling requirements or components and design criteria or the specic job be considered.

An OTDR can be used as a single ended tester, bidirectionally i desired and optionally with

a receive ber or certication testing.

What you need to know about OTDRs. OTDRs were once laboratory equipment that were

dicult to operate and impractical or eld use. They were big, heavy and complicated

or inexperienced technicians to set up or a test and operate accurately. Once a test was

perormed, it was dicult to understand test results. This led to a stigma o ear and

conusion. However, today many new OTDRs are small, light, and easy to use. An ordinary

technician can now troubleshoot like an expert but a basic understanding o how an

OTDR works is still helpul.

Basic operation.AnOTDRinfersloss,reectance,andlocationofevents.Itsends

pulses o light into a ber and uses a sensitive photo detector to see the refections

andplotthemgraphicallyovertime.Inordertoaccuratelytest,theopticalcharacteris-

tics o the ber must be determined and set prior to running the test.

OTDR trace. The OTDR plots the refectance and loss over time in a graphical trace

o the ber. Experienced technicians can read a trace and explain it. For example, in

Figure 4, an experienced eye can spot that one side o a cross connect is exhibitingexcessive loss.

Event analysis sotware. The latest OTDRs run sophisticated sotware that automates

trace analysis and set up o test parameters. Fluke Networks OTDRs can automatically

choose setup parameters, not only telling you where events (instances o refectance

and loss) are on the trace, but also telling you what the events are and qualiying each

o them.

Dead zone.ThisistheshortestberlengthanOTDRcandetect.Itcanalsobe

described as the distance ollowing a refective event ater which another refection

can be detected. All OTDRs have dead zones and should be used with an appropriate

launch ber so that you can measure the rst connection on the link.

Dynamic range. Determines the length o ber that can be tested. The higher the

dynamic range, the longer the ber-under-test can be. However, as the dynamic range

increases, the wider the OTDR pulse becomes and as a result, the deadzone increases.

Ghosts. Not as scary as they might seem, ghosting is caused by an echo due to highly

refective events in the link under test. Fluke Networks OTDRs identiy ghosts on the

trace and tell you where the source o the ghost i s so that you can eliminate it.

Gainers. Another misunderstood phenomenon on an OTDR trace is called a gainer.Simply put, a gainer is an apparent negative loss at an event where there is a change

in the optical perormance. This is usually due to a mismatch between the index o

reraction o two spliced bers or connection o a 50m multimode ber into a 62.5m

ber. This type o event will oten exhibit excessive loss in the other direction.

130 m 7 m 80 m

Figure 5 Connecting the OTDR to installed fber

OTDR port

(if used)

Figure 4 Sample OTDR trace with high loss connector at 137m

OTDR certifcation set-up

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OTDR certifcation set-up

Setting up or OTDR Certifcation Testing

Setup: Turn the rotary switch to Setup and choose Settings rom menus in ve setup

screens.

1. First, select which port you want to test rom (multimode or singlemode), what test

limit you want to use, the ber type, and desired wavelength.

ItispossibletocreatemultiplesetsofOTDRtestlimitsandselectonefora

particular job. Each OTDR test passes (Figure 6) or ails (Figure 7) based on a

comparison against the selected set o test limits.

2. On the second setup screen, you may then set launch ber compensation, designate

which end you are testing rom, and notate what you want to call each end o the ber.

Using launch fber compensation (LFC)

Launch ber compensation is used to simpliy testing

and remove the launch and receive bers losses and

lengths rom measurements.

Itshowsyouwhereyourlaunch(and/orreceive)

ber is on the trace, and eliminates it rom the

certicationtestresults.Ifyouareacontractor,

your customers want to know where an event

is in their ber plant, not where it is on your

test setup. When you enable LFC, a connector

that is 50m rom the patch panel will show up

at 50m, not 150m on the trace. Just turn the

rotary switch to Setup, go to the 2nd tab, and

enable Launch Fiber Compensation. Then turn

it again to Special Functions, and choose Set

Launch Fiber Compensation. Choose Launch

only i you are just using a launch ber, or

Other Options i you are also using a receive

ber.

3. Third, designate the ber characteristics or allow

deault to the selected ber in the rst step or

choose User Dened and select Numerical

Aperture and Back-scatter coecient or the

ber-under-test.

4. Now choose rom the menu to set Distance

Range, Averaging Time.

5. Finally, choose rom the menu to set Pulse Widthsand Loss Threshold.

With the DTX Compact OTDR, many settings such

as Distance Range, Averaging Time, Pulse

Widths, and Loss Threshold can be automatically

set. Just turn the rotary switch to Autotest, and

when you push the test button, the OTDR will

choose the most appropriate setting or the ber

that you are testing.

Running an autotest. Now that you are all set up

or testing, turn the dial to Autotest, plug in your

launchberandpressTest.Ifitpasses,pressSave,

namethetest,andtestthenextber.Ifyouwantto

see a trace just press the 1 sotkey. The event table

and limits are also accessible via sotkeys on the

main screen.

Summary o extended certifcation

OTDR traces characterize the individual compo-

nents o a ber link: connectors, splices and other

loss events. Extended certication compares the

data to specications or these events to deter-

mine i they are acceptable

Critical because it identies aults that may be

invisible to basic certication

Evidence that every component in a ber optic cabling system was properly installed

Figure 6 Pass Screen on the

DTX Compact OTDR

Figure 7 Fail Screen on the

DTX Compact OTDR

Figure 8 Trace Screenshot on the DTX

Compact OTDR

Figure 9 Pass Trace Screenshot on

the DTX Compact OTDR

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As with the rst tier o testing, results can be downloaded to a PC and managed with

LinkWareResultsManagementSoftware.ItiseasytomergeOTDRtestresultswiththe

otherrecordsifthesamenamingsequenceisused.TheFiberInspectoroptionforOptiFi-

ber also allows end-ace images to be merged into the same test results record to prove

cleanliness and to generate proessional reports that combine all the test data into onedocument. These can be easily created and printed out or emailed in PDF orm.

Cable certifcation test strategy

There are several possible ways to perorm a complete certication test o ber optic

cabling. The standards are clear about dening required and optional tests, test limits and

test equipment that may be used. But they do not suggest how the testing should be per-

ormed or optimum eciency in the eld. Based on decades o working with contractors,

installers, technicians, Fluke Networks has developed proven, best-practice procedures to

perorm a complete ber certication in the most ecient way.

Make sure that design criteria and test limits are established beore installation

Conrm proper ber strand polarity,

end-ace conditions, and veriy loss

with simple verication tools during

installation

Perorm extended tests using the tier

2 certication tests (OTDR analysis)

as the rst certication step. Doing

so:

- Ensures connector perormancemeets generic cabling standards or

system designers requirements

- Qualies workmanship or cabling

installation

- Identiesproblemsforimmediate

troubleshooting with OTDR

Secondly, perorm basic tier 1 test or

the channel against the application

standard. This certies channel length

and loss and calculates margin based

on the standard

Ifbidirectionaltestingisnotrequired,measurechannellossatthewavelengthofthe

application

5. Common FaultsInsufcientpowerorsignaldisturbances

resulting rom common aults cause ailures

in optical transmission.

Fiber optic connections involve the transmis-

sion o light rom one ber core into another.

Fiber cores are smaller than the diameter o a

human hair. To minimize loss o signal power,

this requires good mating o two ber end-

aces.

Contaminated fber connections. The leading cause o ber ailures results rom poor

connector hygiene. Dust, ngerprints, and other oily contamination cause excessive loss

and permanent damage to connector end-aces

Too many connections in a channel. Simple, but it is important to consider the total

allowable loss (per intended application standard) and typical loss or connector type

during the design process. Even i the connectors are properly terminated, i there are

too many in a channel, the loss may exceed specications

Misalignment. The best way to achieve good ber alignment is to use the two bers

together with a precision splicing machine. But or several practical reasons, connection

o bers is oten done mechanically with ber optic connectors. There are many com-

mercially available connector types that all have their advantages and disadvantages.

Typical loss specications are a good proxy or how good they are able to align bers.

Any such specications used or data communications should be compliant with Fiber

OpticConnectorIntermatibilityStandard(FOCIS)standards

- Poor quality connectors or aulty termination. Good quality connectors have very

tight tolerances in order to maintain precise alignment

- End-ace geometry. Perormance o ber optic connectors is largely a unction o the

geometry o the end-ace. This geometry can be measured in a laboratory with preci-

sioninterferometryequipment.Intheeld,thefollowingparametersareinferredin

loss and refectance measurements

Roughness. Scratches, pits and chips produce excess loss and refectance

Radius o curvature. The convex surace o the connector should nicely mate up with

another connector

Apex oset. The core o the ber should be centered near the highest point o the

connector

Fiber height. A protruding (underpolished) ber does not mate well and an undercut

(overpolished) connector will perorm poorly due to the presence o an air gap

- Unseated connectors. A connector may be plugged into an adapter bulkhead

but may not be seated and connected with its mate. Worn or damaged latching

mechanisms on connectors or adapters are sometimes the culprit

- Poor cable management. Strain on a connector may cause misalignment due to

becoming partially retracted, broken, or unplugged

Figure 10 Sample LinkWare Results Management

Sotware printout

Figure 11 Example o a common cause o a

fber ailure

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Polarity. Perhaps the simplest ber cabling ault is a reversal o t ransmit and receive

bers. This is usually easy to detect and repair. But sometimes connectors are duplexed

together and must be broken apart to be reversed. Standards designate polarity with a

labeling convention that is seldom taken advantage o, resulting in conusion

- Polarity should be designated with A and B labels or colored boots- A is or transmit and B is or receive; OR, red is or transmit and black is or receive

Poor cable management, system design, or damaged cable also causes aults in ber

cabling systems. Fiber has a very high tensile strength, but is susceptible to crushing and

breaking i abused.

Bends. Macro and microbending caused by tight cable ties or bend radius violations

result in excessive and unexpected loss

Breaks. Light will no longer propagate past a location where the glass is crushed or

cracked in an optical ber

Intersymbol intererence (ISI). Disturbed Signal is a ault that is usually the result

o poor system design. A system that i s not certied with the application standard in

mindissusceptibletoISI

- Modal dispersion rom violation o distance limitations on multimode bers

- Refections rom too many highly refective connectors causing increased bit errors

due to excessive return loss

Troubleshooting basics Keep it clean. Dirty connections are the worst cause o ailing connections and testing

challenges. Clean bers each time they are connected. You can veriy that bers are

cleanbyusinganinstrumentsuchasaFiberInspectormicroscopetoexamineberend

aces.

- Dust blocks light transmission

- Finger oil reduces light transmission

- Dirt on ber connectors spreads to other connections

- Contaminated end-aces make testing dicult

- Remember to inspect equipment ports, as these equipment ports (routers, switches,

NICs)getdirtytoo

Use the correct test setup. Test standard per specications will ensure that you get the

most accurate, consistent, understandable and repeatable results

Use recommended ber mandrels to improve loss measurement accuracy and

repeatability.

High quality TRCs and launch bers should always be used; use o random,

questionable quality test cords should always be avoided.

- All TRCs or loss testing should should be delivered with good test result data

- Test cords should make polarity easy or you Fluke Networks cords eature

red boots on the end at which light enters and black boots on the end at which

light exits

- Cords should be kept clean and replaced when they show signs o wear

Choose test limits that are appropriate to both generic cabling standards and

application standards

6. End-Face Inspection and CleaningInspection

Proper inspection helps in detecting two o the most common (yet easiest to prevent)

causes o ailure: damaged and dirty ber end-aces.

Damage occurs in the orm o chips, scratches, cracks, and pits to the core or cladding and

can result rom mating contaminated end-aces. Tiny oreign debris let on the core can

also damage end-aces during the mating process as they are connected together.

As alluded to earlier, sources o contamination are everywhere, whether it be rom a touch

o a nger or the brush o a clothing abric, much less the omnipresent dust or static-

charged particles in the air. Ports are also subject to the same contamination but are oten

overlooked. Mating a clean connector to a dirty port not only contaminates the previously

clean connector but can also cause ber damage or ailure. Even the protective cover-

ings or dust caps on straight-rom-the-package connectors and assemblies can cause

contamination due to the nature o the production process and materials.

The typical assumption is that a quick visual check o the end-aces is sucient to veriy

cleanliness. As mentioned previously, the cores o these bers are extremely small

ranging rom roughly 9 to 62.5m. Put into perspective, with a diameter o 90m,

the average human hair is anywhere rom 1.5 to 9 times larger! With such a tiny

core size, it is impossible or any end-ace deects to be spotted without

the aid o a microscope.

There are two types o fber inspection microscopes:

Optical (Figure 12) tube-shaped and compact, these

enable you to inspect the end-aces directly. Popular

because they are inexpensive; however, they are not

able to view end-aces inside equipment or through

bulkheads.

Video (Figure 13) small optical probe is

connected to a handheld display. The probe size

makes them excellent or examining ports that are

in hard-to-reach places; large displays enable easy

identication o end-ace deects. They are also

saer as they show an image and not the actual

end-ace being observed, reducing the risk o

exposing ones eye to harmul lasers.

Within the context o inspecting ber optics

showing the user what the naked eye cannot see, the

primary desired attribute is detection capability

basically the smallest-sized object that it can detect.

Figure 12

Optical microscope

Figure 13

Video microscope

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1918

Cleaning

Properly cleaned end-aces can actually add up to 1.39 dB onto your loss allowance.

(Figure 14).Inotherwords,ifyouhaveaberplantwithanoveralllossof5.0dB

against a specied budget o 4.5 dB, cleaning any dirty end-aces may help to drop the

link loss down to just above 3.6 dB, providing a Pass and plenty o head-room. Conse-quently, it is important to choose your cleaning tools and methods wisely while avoiding

commonly-practiced bad habits. Perhaps the most typical mistake is using canned air to

blast ber connectors or ports. While helpul or displacing large dust particles, it is

ineective on oils, residues, or tiny static-charged particles that are equally detrimental

in causing ailures.

Figure 14 Comparison between a clean and dirty fber end-ace

The same problem occurs when using shirt sleeves or clean cloths to wipe connectors;

in act, the trace amounts o lint and dust-attracting static rom using such materials will

likelyaddtothecontaminationratherthanreduceit.Evenisopropylalcohol(IPA),which

has historically been viewed as an acceptable solvent, is proving to be inerior to specially

formulatedsolutions.IPAsinabilitytodissolvenon-ioniccompoundssuchaspullinglube

and buer gel, and its residue-leaving evaporation process make engineered solvents the

superior choice. When using these solvents, the proper cleaning order is wet to dry using

clean, lint-ree wipes (Figure 15).

Figure 15 Wet to dry cleaning methodology. Apply a small spot o solvent to the starting edge o

a wipe. Holding the end-ace connector perpendicularly, swipe the end-ace rom the wet spot to the

dry zone.

Clean fber end-ace Contaminated fber end-ace

The types o cleaning resources vary in complexity and price, ranging rom simple wipes

to devices that incorporate ultrasound with water. Which tool you use will be dependent

upon need and budget but or the majority o the cabling jobs and projects, the pairing

o lint-ree wipes and swabs with engineered solvents now ound in ber inspection,

certication, and cleaning kits will be sucient.

7. ConclusionCablinginstallationisamulti-stepprocess.Itisaprudentpracticetocertifythecabling

system ater installation to ensure that all installed links meet their expected level o

perormance. Certication will likely identiy some ailing or marginally passing results.

Inordertodeliverahighqualitycablingsystem,thedefectsthatcausethefailuresand

marginal passes must be uncovered and corrected.

Fluke Networks ull suite o ber certication instruments (Appendix 2) have an unpar-

alleled history o providing unique and powerul diagnostics assistance to installation

technicians. By knowing the nature o typical aults and how the testers diagnostics report

them, you can signicantly reduce the time to correct an anomaly, an installation error, or

a deective component. Personnel responsible or the networks operation can also benet

rom the diagnostic capabilities o a certication test tool; with the testers assistance,

they can limit the duration o network downtime and restore service quickly.

We highly recommend that you thoroughly amiliarize yoursel with the capabilities o your

testtoolitistrulyamodestinvestmentthatpaysforitselfmanytimesover.Inaddition

to your precision instrument, Fluke Networks also provides a wide variety o expert and

timely support options. Whether you are an installer, network owner, or contractor, the

ollowing resources are available:

White papers and Knowledge Base articles insightul studies and helpul advice on

relevant structured cabling topics

Unsurpassed technical assistance rom the highly trained Fluke Networks Technical

Assistance Center (TAC)

Certifed Test Technician Training (CCTT) classes available around the world

Gold Support program comprehensive maintenance and support including priority

repair with loaner, annual calibration and priority TAC support with ater hours and

weekend coverage

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8. Glossary

Certifcation testing the process o testing the transmission perormance o an installed

cabling system to a specied standard; requires an OLTS or Tier 1 certication

and an OTDR or Tier 2 certication

Channel end to end transmission medium between a transmitter and receiver

dB unction o a ratio o two power levels, typically used to express the relation o the

output power to the input power such as the gain in an amplier or the loss in a

transmission line

dBm power level expressed as the logarithm o the ratio relative to one milliwatt

FiberInspector Fluke Networks popular line o handheld ber end-ace and bulkhead

port inspection instruments, ranging rom tube to video microscopes

Gbps gigabits per second

Launch cord fber length o ber placed between the l ink-under-test and the OTDR to

improve the OTDRs ability to grade the near-end connector and any abnormalities

in the rst connection

LED Light Emitting Diode, a relatively low-intensity light source

Link the physical cabling or a transmission

Mbps megabits per second

OLTS Optical Loss Test Set, a baseline Tier 1 certication instrument that measures the

loss o a link over its length

LSPM Light Source Power Meter, basic ber verication instrument composed o a power

meter and a source to measure loss over a link

TRC Test Reerence Cord, a high-quality ber cord between 1 to 3 meters long with

high perormance connectors, ideally with end-aces with special scratch resistant

hardened suraces that enable numerous insertions without degradation in loss

perormance

VCSEL Vertical Cavity Surace Emitting Laser, commonly used in multimode light sources

Verifcation testing the process o testing the transmission perormance o an installed

cabling system to ensure that it meets a minimum threshold

VFL Visual Fault Locator, optical source that transmits a low-powered laser to identiy

breaks in ber links

AppendixFlu

keNetworksFiberTestandTroublesho

otingInstruments

Inspection&Cleaning

PlantCharacterization&Troubleshooting

(Tier2Certifcation)

FiberInspectorPro/

MiniVideoMicro-

scopes

FiberOpticCleaning

Kits

SimpliFiberPro

PowerMeter&

FiberTestKits

VisiFaultVisual

FaultLocator

DTX

Cable-Analyzerw/

CompactOTDR

Module

OptiFiberOTDR

Checkorfberend-acecontaminationordamage

3

3

Cleancontamination

3

Checkconnectivity

3

3

3

3

3

3

Checkpolarity

3

3

3

3

Veriylossoverentirelinktoensurelossbudgetnot

exceeded

3

3

3

3

3

Dual-fberlosstesting

3

3

Tier1certifcation

3

3

3

Locateaults

3

3

3

Locatemultipleconnections&lossevents

3

3

Measureeventloss

3

3

Reectancemeasurements

3

3

Tier2certifcation

3

3

Pass/ailresults

3

3

3

3

Documenttestresults

3

3

3

3

Sourcetype

LED,

FP

Laser

LED,

FP

Laser,and

VCSEL

LED,

FP

Laser,and

VCSEL

Laser

LED,

FP

Laser

LED,

FP

Laser

LossLengthTesting

(Tier1Certifcation)

DTX-CLT

CertiFiber

OpticalLoss

TestSet

DTX

CableAn

alyzer

with

FiberMo

dules