bisc best practice fo testing

7/17/2019 BISC Best Practice FO Testing

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Testing and troubleshooting

enterprise fiber-optic cabling

Presenter:

Neftali UsabalFluke Networks - LATAM



Agenda

• Testing Methods and Standards

– Why we test optical systems

– Terminology & types of testing

– Standards based testing requirements

• Cleaning and Inspection

•Attenuation (loss)Testing Overview (Tier 1)

• OTDR Testing Overview (Tier 2)



CERTIFICATION TESTING OF OPTICAL CABLING

• Product acceptance upon receipt

• Installation Acceptance following

deployment of system

• Accounting/Documentation of your

system for:

– As Built records

– Performance Benchmarking

– MAC & Rework

• Proof/Verification that the final system

meets design specifications and

contractual obligations

Efficient and properly performed certification testing will

ensure that you get paid fast and avoid callbacks!



Factors Affecting Signal Loss

• Intrinsic

• Splice Loss (non reflective event)

• Connector Loss (reflective event)

• Macrobending

• Microbending



Factors Affecting Performance

• Chromatic Dispersion

(Singlemode Fibers)

• Polarization Mode Dispersion

(Singlemode Fibers)

• Modal Dispersion (Multimode

Fibers)



Dispersion or pulse broadening



Testing Standards

• ANSI/TIA/568-C.1— Commercial Building Telecommunications Cabling

Standard.

• ANSI/TIA/568-C.3— Optical Fiber Cabling and Components Standard. Includes guidelines for Field-

Testing Length, Loss and Polarity of Optical Fiber Cabling Systems

• ANSI/TIA/-526-14-A— OFSTP-14A Optical Power Loss Measurement of Installed

Multimode Fiber Cable Plant (ANSI/TIA/EIA-526-14A-98)

• ANSI/TIA/526-7— OFSTP-7 Measurement of Optical Power Loss of

Installed Single-mode Fiber Cable Plant

(ANSI/TIA/EIA-526-7-98)

• ISO IEC 14763-3

– Defines testing methods and limits including definition of “test Reference Cords”

• TIA/TSB 4979 Methods for meeting Encircled Flux launch conditions



•Titled:

– Generic Telecommunications Cabling for Customer Premises –

Addendum 2, General Updates

– Published August 2012

• New application limits – 40GBASE-SR4 (100 m, 1.9 dB over OM3)

– 40GBASE-SR4 (150 m, 1.5 dB over OM4)



• Limits are getting tighter, CPR and MPD no longer good

enough

ANSI/TIA-568-C.0-2



•Was considered adequate for the time (2003)

• Test limits getting tighter

– 1000BASE-SX (2.6 dB over OM1)

– 10GBASE-SR (2.6 dB over OM3)

– Consultants tightening loss budgets

– Manufacturers tightening loss budgets

• ISO/IEC 14763-3 (2006) changed to MPD

– Modal Power Distribution

– Tighter than CPR

– Now also adopting Encircled Flux to replace MPD

ANSI/TIA-526-14-A



• Replaced with ANSI/TIA-526-14-B (Oct 2010) titled: – Optical Power Loss Measurements of Installed

Multimode Fiber Cable Plant

• Replaced Coupled Power Ratio with Encircled Flux

– More to come on this later!

ANSI/TIA-526-14-A (2003)



Optical Test Equipment Summary

Type of

Test Equipment Investment Used For Required Tests For

VisualVFL,

Microscope,$300 - $4000 Verification Rarely

Continuity, Polarity,Cleanliness

Power & Attenuation

PowerMeter

$1K -$5k

Verification tomanually

determined lossbudgets

Sometimesas proxy for

Tier 1

Power, loss,continuity, polarity

Attenuation

Testing(Tier 1)

Optical

LossTestSet (OLTS) $6K - $13K

Certification to

performancestandards Always

End -to – end Loss,Continuity, length

polarity & comparesto performancestandards

OTDR

(Tier 2)OTDR $8K - $17K

Certification &Troubleshooting

to ensureinstallation

workmanship

Typical

Analyzes Events(splice & connector)

by measuring

reflectance



Fiber inspection and cleaning



13

#1 Problem: Dirt!

• Contaminated connector end-faces: Leading cause of fiber linkfailures

• Particles of dust and debris trapped between fiber end facescause signal loss, back reflection, and damaged equipment

• Many Sources of contamination:

• Equipment rooms & Telecommunication rooms in filthy environments• Improper or insufficient cleaning tools, materials, procedures

• Debris and corrosion from poor quality adapter sleeves

• Hands of technicians

• Airborne



14

y o er nspec ng nFaces?

• To Prevent Damage• Debris will embed in glass when contaminated connectors are mated

• When embedded debris is removed, pit remains in glass as permanentdamage

• Pits cause signal loss and back reflection

• Debris causes other damage such as chips and scratches



Good Connector

Fingerprinton Connector

Dirty Connector

Inspection images

Real images as captured from the Fluke Networks Fiber Inspector™



COMMON MISCONCEPTIONS

• Protective caps keep end-faces clean - NO

– Caps are a source of contamination: mold-release compound from manufacturing

– End-faces are NOT clean when they comepre-terminated from the factory in a sealedbag

• Canned air will blast away dirt - NO – Is ineffective on smaller, static-chargedparticles

– Blows larger particles around rather thanremoving them

– Is ineffective on oils and compound

contaminants

• Isopropyl alcohol (IPA) is the best solvent – NO

– IPA does not work on non-polarcontaminants

Pulling lubricants, buffer gels, etc.

– IPA leaves a residue when not used properly



Cleaning with IBC Cleaners

• IBC™ OneClick Cleaners for cleaning different end

faces/connectors — no training required

• 1.25 mm LC and MU connector and end faces

• 2.5 mm SC, ST, FC, E2000 connector and end

faces

• MPO/MTP connector and end faces

• Cleans Ports on devices and patch panels

as well as Cords ….with an adapter

• Dry cleaning is less efficient for cleaning grease

(dried skin oil) than wet cleaning with a solvent and

swabs/cleaning cubes



CLEANING WITH SOLVENT PEN

• Start with a clean, lint-free wiping surface every time – Material left exposed accumulates ambient dust – Material used once should not be used again

• Use a minimal amount of specialized solvent

– Important that solvent be removed after cleaning – Move the end-face from the wet spot into a dry zone

Cleaning with a saturated wipe will not fully removesolvent

Cleaning with a dry wipe will not dissolve contaminantsand can generate static, attracting dust

• Proper handling and motion

– Apply gentle pressure with soft backing behind cleaningsurface – Hold end-face perpendicular to cleaning surface – No figure-8 motion as that’s for polishing only

• Inspect both end-faces of any connection before insertion

– If the first cleaning was not sufficient, then clean again until all

contamination is removed



Company Conf ident ial

Hands ON - Fiber Inspection• Tap TOOLS

• Tap FiberInspector

• Focus the image with the knobon the probe

• Press to “pause” or enter

the “still” mode



Company Conf ident ial

Hands On: Fiber Inspection• Tap SCALE ON

• Tap NEXT SCALE

• Drag fiber to center of scales

• Zoom on image

• Tap GRADE

• Tap GRADE again



Optical Loss Testing



• Double Ended Test – Absolute Loss measurement

• Compares Loss to industrystandards

– Pass/Fail Results

• Other helpful Capabilities – Length measurement

– Project/Loss budget Wizard

– Two fibers at a time – Bidirectional testing

– Set Referencing Wizard

Tier 1 Fiber Certification with OLTS



These things must be done correctly!• Use good/clean Test Reference Cords

– ISO/IEC 14763-3 (2006)

– Reference grade connectors were required

– Multimode ≤ 0.10 dB – Singlemode ≤ 0.20 dB

• Set Reference correctly!!

– Helps minimize uncertainty

– Eliminates “negative loss” incidents

• Proper Launch Conditions

– Encircled Flux Per TSB 4979

Managing Uncertainty



• In ISO/IEC 14763-3 (2006), cords were recognized as a source

of great uncertainty

• This standard reduced uncertainty by defining the

performance of the test cord connector

• Reference grade connectors were required

– Multimode ≤ 0.10 dB

– Singlemode ≤ 0.20 dB

Impact of test reference cords

0.75 dB0.10 dB

≤ 0.30 dB

0.75 dB0.20 dB

≤ 0.50 dB



• Sadly, most folks are setting a reference this way

• Issues – You have no idea what the loss is in the adapter

– Whatever it is, it’s subtracted from your measurement

– The uncertainty is horrendous – negative loss

Setting a Reference…What is done today

? dB



• So you end up with this




What is done today

x dB z dB

y dB

Measurement = x + y + z - ?



• Let’s take an example




What is done today

0.75 dB



• Let’s take an example




What is done today

0.3 dB 0.3 dB

0.1 dB

Measurement = 0.3 + 0.1 + 0.3 – 0.75

= -0.05 dB



• ANSI/TIA describes this as Method A

• Not for enterprise cabling systems – Used in long haul measurements

– Uncertainty of one connector not considered critical?

What is done today

? dB



• For testing an installed fiber optical link, should always use

the 1 Jumper Reference Method

• Does require the test equipment to have interchangeable

adapters on the INPUT ports

What is done today

emove rom por



• It’s ok to remove the fiber from the input ports

• You cannot remove the fiber from the output port, doing so

will invalidate the reference you just made

emove rom poronly



• To the INPUT ports

Connect known good cord



• To the INPUT ports




• How do I know if those cords are good?


f h d



• Connect them together using a singlemode adapter and

measure the loss

Verifying the cords

ISO/IEC 14763-3

• ≤ 0.1 dB for Multimode

• ≤ 0.2 dB for Singlemode

ANSI/TIA-568-C.0

• ≤ 0.75 dB?

Cabling Vendors

• ≤ 0.50 dB?

Why not save this as proof of good test reference cords?

*

* This can be up to 0.15 dB for LC

f d l



• ISO/IEC 14763-3

– 1 Jumper method (0.1 dB for Multimode and 0.2 dB for Singlemode)

• ANSI/TIA-568-C.0

– Does not call out test reference cord values (≤ 0.75 dB?)

– You are expected to specify this

–

• Require documentation of TRCs

Test Reference Cord Values

?



onnec o e er op c



• ANSI/TIA-568-C.0

• First and last connections ≤ 0.75 dB

• All other connections ≤ 0.75 dB

onnec o e er op clink

≤ 0.75 dB ≤ 0.75 dB

L h di i



• Diagrams shown to visualize the issue as best as possible

Launch conditions

Source 1

Over filled

Source 2

Under filled

assessmen



assessmenimprovement

Source 1

Over filled

Source 2

Under filled

EF specifies power throughout core using multiple control radii.

EF provides tight tolerance on mode power distribution in the outer radii

enabling improved agreement between EF-compliant test instruments.

TIA TSB 4979



• Titled:

– Practical Considerations for Implementation of Multimode Launch

Conditions in the Field

• TSB = Telecommunications System Bulletin

– Not an official standard

– An advisory document

– Chances are will end up in ANSI/TIA-568-D.3

• Helps users understand Encircled Flux and the options forimplementing it

TIA-TSB-4979

rac ca mp emen a on o



• Option 1

– Use an external mode controller

– Replaces the mandrels

rac ca mp emen a on oEF

rac ca mp emen a on o



• Option 2 -Matched source and test referencecord

rac ca mp emen a on oEF

er er er ca on



• At a minimum, use a mandrel

–This does not yield the controlled launchcondition the industry desires that is EncircledFlux

• Don’t use a VCSEL source – Too much variability

– Not standards compliant

• Consider investing in fiber optic test

equipment that allows a 1 JumperReference – reduced uncertainty

• Verify your Test Reference Cords – Save the results and make it part of your

documentation

• If Encircled Flux is a contractualrequirement, or you care about getting as

many “passes” as possible: – Reference TIA/TSB 4979

• EF Mode Controllers

• DTX-EFM2

• CertiFiber Pro

er er er ca onSummary



46

OTDR TEsting



What is An OTDR?

-OptiFiber Pro OTDR

10.6 x 5.0 x 2.5

inches

5.7 inches

touchscreen display Taptive ™

gesture based

user interface

EventMap8-hour battery life

Singlemode,

Multimode and

Quad modules

What Does An OTDR Do?



48

What Does An OTDR Do?

OTDR Port

Connector

Processing

& Control

Color

Display

Directional

Coupler

Very SensitivePhoto

Detector

Two

Laser

Diodes

• Sends pulses of light out

• Keeps checking for

reflected light

• The farther the light goes,the more time it takes to

come back

• When light hits a

connection, an extra spike

of light reflects back

• The farther the light goes,

the more loss it encounters,

so less comes back

(measures length)

(measures fiber loss)

(finds connections)

OTDR

Fiber

Under

Test

Optical Fiber

Electrical

OTDR in Action



49

OTDR in Action

The OTDR measures reflected energy and

NOT the transmitted light level.

Distance

Loss



50

OTDR Technology

• Rayleigh Scattering

• Fresnel Reflection



51

Scattering, (Rayleigh

Scattering) occurs whentransmitted light energy is

higher than what the glass

molecules can absorb and

the energy is released in all

directions. It is the major

loss factor in fiber.

Backscattering occurs

from about 0.0001%

of the light being

reflected back to the

OTDR.

Rayleigh Scattering



52

Coupling loss air gap

causes loss of light

transmitted

Fresnel Reflection occurs

when light traveling in one

material encounters a

different density material

(like air). Up to 8% of the

light is reflected back to

the source while the restcontinues out of the

material.

Fresnel Reflection

What is reflectance?



What is reflectance?

An air gap between the end faces of a fiber

also cause Fresnel reflections to occur.



What do those numbers mean?

Reflectance is the preferred term when characterizing a single

connector.• It is a measure of the amount of power reflected by a connection.

• It includes one connector

• It is always negative.

• Smaller is better (e.g. -35dB is better than -20dB) Refl10log

P reflected

P incident

Return Loss is the preferred term when characterizing an entire link

• It is a measure of the amount of power NOT reflected by a link.

• Includes all connections and fiber

• It is always positive.

• Bigger is better (e.g. +35dB is better than +20dB)

reflected

incident

P

P log10ORL

Why should you care?



Why should you care?

High reflectance causes increased Bit Error Rates

(CRC errors) on the network



56

What Do OTDR Test RESULTS Look Like?

l ( )



Test Example: Tier 2 (OTDR)TR

MC X

XX X

Backbone Cables

Horizontal Cables

OTDRcharacterizes linkdetails

ven a e



58

ven a efrom OTDR

EventMap Event Table

EVENTMAP



EVENTMAP

• Easy to understand map of thephysical infrastructure

• Icons represent events.

• Passing reflective event

• Failing reflective event• Hidden reflective event

• Passing loss event

• Failing loss event

• Hidden event’s loss is added toprevious event’s loss

Typical OTDR TEST RESULT



60

Typical OTDR TEST RESULT

Backscatter

Reflection

Reflective Event



61

Reflective Event

Connector

Loss Event



62

Loss Event

Non-reflective eventSplice or severe bend

End Event



63

End Event

End of Fiber

Gainer Event



64

Gainer Event

50 micron fiber connected to a 62.5 micron fiber

Gainer

GHOST EVENT



65

Ghosts

Dynamic Range



66

Dynamic Range

• Determines the length of fiber that can be tested

• Provided as a dB value

• Larger values mean longer distance (typically for telcos)

… and a larger dead zone

• Premises OTDR’s do not need a large dynamic range …

and benefit with a small dead zone

• Pulse needs to be wide enough to get to

the end of the fiber

Dynamic Range



67

Dynamic Range

Measurement

Dynamic

Range

Initial backscatter level at OTDR front connector

Dynamic range is the maximum attenuation level that the test

equipment can recognize and therefore may be used to

determine how long of a fiber can be measured.

Noise

dB

Length00

Dead Zone



68

• A dead zone is like when

your eyes need to recover

from looking at the bright

sun or theflash of a camera

• It can be reduced by using

a lower pulse width, but itwill decrease the dynamic

range.

Two Types of Dead Zones



69

Two Types of Dead Zones

• Typically occurs in a tracewhenever there is aconnector

• The OTDR receiver goes“blind” from the strong

reflection

•Includes duration of thereflection and recoverytime for the receiver.

Eventdead zone

Attenuationdead zone

Attenuation Dead Zone



vs. Event Dead Zone• Event Dead Zone is the minimum distance the

OTDR can detect an event after the preceding

event

• OFP Typical Event Dead Zone is:

• 0.5m @ 850 nm, 3 ns, -40 dB Reflectance

• 0.7m @ 1300 nm, 3 ns -40 dB Reflectance


• 0.6 m @ 1550 nm, 3 ns, -50 dB Reflectance

Attenuation Dead Zone



vs. Event Dead Zone• Attenuation Dead Zone is the minimum

distance between two events on an OTDRwhere the OTDR can assess the event loss

• OFP Typical Attenuation Dead Zone is:

• 2.2m @ 850 nm, 3 ns, -40 dB Reflectance• 4.5m @ 1300 nm, 3 ns -40 dB Reflectance


• 3.6 m @ 1550 nm, 3 ns, -50 dB Reflectance

s ng aFib



72

gFiber

LaunchFiber

Will give loss of the

first connector

TailFiber

Will give loss of thelast connector

Launch & TAIL Fiber



73

• A must for measuring the loss of thefirst and last connector in a fiber link

• Launch fiber must be significantly longer than the

attenuation dead zone of the OTDR

• With short dead zones you can use a short launchfiber

Launch Fiber Compensation



74

p

Getting to Systems Acceptance



Getting to Systems Acceptance

• Verification Testing

– Typically performed after MC,IC and / or HC connectorinstallation

– Improves attenuation testingtime

• Attenuation Testing – Final System Verification

– Certifies Loss is withinPerformance Standardrequirements

• OTDR Testing – Tests links and point

discontinuities

Support Resources



Support Resources

• Knowledge Base:

– http://myaccount.flukenetworks.com/f net/en-us/supportAndDownloads/kb

• Technical Assistance Center24 x 7 assistance:

– [email protected]

– USA: 1-800-283-5853

• Resources for “Experts” – Designers:

http://www.flukenetworks.com/expertise/role/Architects-Consultants-Designers

– Installers:http://www.flukenetworks.com/expertise/role/guide-to-contract-installers-and-installation

http://myaccount.flukenetworks.com/fnet/en-us/supportAndDownloads/kb


mailto:[email protected]





http://www.flukenetworks.com/expertise/role/guide-to-contract-installers-and-installation
























mailto:[email protected]





bisc best practice fo testing

Documents

testing standards ansitia568

loss budgets manufacturers

loss budgets isoiec

otdr testing overview

test limits

testing requirements

mpd ansitia

coupled power ratio