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8/9/2019 13 Fluke Network

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Common copper and fiber certification

mistakes and how to avoid them

Adrian Young

Fluke Networks

May, 2014BICSI Andino


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In this presentation

Survey results from 803 contractors in 53 countries

Discuss preventative measures

A look at diagnostic tools for copper and fiber links

Using real world examples

Understand how they work and their limitations


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803 contractors in 53 countries

US

55%Asia

28%

EMEA

17%

BusinessManager

6%

Cabling

Tech-

nician

22%

Other

23%Owner/Co

-owner

17%President

/Vice-

President

5%

Project

Manager

27%


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I know what you did last month

(Links installed)

Copper Fiber Total

US 317,162 (64%) 177,881 (36%) 495,043

Asia 186,833 (63%) 109,112 (37%) 295,945

EMEA 113,328 (68%) 54,397 (32%) 167,725

Totals 617,323 (64%) 341,390 (36%) 958,713

All results refer to the prior 30 days.


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Top eight problems (hours wasted)

Average amongst all respondents in the previous 30 days


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Avoiding twisted pair failures


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Wrong test limit used

New thinking

Allow project managers to configure the test equipment in

advance (setup multiple projects/jobs)


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Wrong Cable IDs used

New thinking (existing feature in most testers)

Allow project managers to configure the test equipment in

advance


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Rule out the field tester?

ANSI/TIA-1152 section 4.3.1

The owner of the field tester should construct a reference

link. Repeated measurements on this link should result in

the same results within the magnitude of the accuracy

specifications. Comparisons should be made at the worst

case results across the frequency band.

Create a portable link(s) where theconnectors and cable are anchored down so

the characteristics of the link do not change


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Can you avoid this?

This installation showed poor margin performance

Customer rejected results

Paid for a premium cabling system


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Spot check the cable first

Terminate some of the cable

Pull around 30 m of cable out of the box/off the reel

Terminate it and test to a Permanent Link

Are you really testing the cable? Measurement includes your connections, so not really

Assumes your terminations are good

Connection Connection

Cable

Perm. LinkAdapter

Perm. LinkAdapter


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Channel measurements

Exclude the connection to the test equipment at each end

Test equipment vendor must do their best to remove the

effects of the mated connection in the adapters Can be achieved using gating techniques (IDFTs)

Connection Connection

Cable

NEXT

FEXT

Return Loss

NEXT

FEXT

Return Loss


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Just the cable Terminated with RJ45 plugs at each end

Measurement will be just the cable on its own

Suggests a possible field test for raw cable off the reel / out of box

Depends on how good the cancellation of the adapters are

Need the limits for just the cable to compare to

Cable

NEXT

FEXT

Return Loss

NEXT

FEXT

Return Loss

Make sure the plug you are using is for solid cable


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Example Link #1

* Indicates result is within theaccuracy of the field tester

Premiumcable was used, so this shouldnot be showing such a small margin

Customer would not accept a marginal pass

Tested to Category 5e Permanent LinkperANSI/TIA-568-C.2 and ANSI/TIA-1152


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Example Link #1

Conclusion:Testing the cable before or during theinstallation can prevent delay$

Tested to Category 5eANSI/TIA-568-C.2cable onlylimits


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Diagnosing twisted pair failures

Speed up fault resolution


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Return Loss Diagnostics

Converting from MHz to metres

TDR IDFTs have used in field test equipment

since 2004

Red lines indicate themaximum expected

level of impedanceanomalies in the cable


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NEXT Diagnostics

Converting from MHz to metres

Used in field test equipment since 1995

Refined to deal with higher frequencies in 2013

Red lines indicate themaximum expected

level of NEXT in theconnections


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Example Link Test #2

Return Loss fails Failing at lower frequencies

Suggests a cable issue


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Return Loss fails Cable anomalies typically less than |0.8%|

Multiple anomalies exceeding |0.8%| here

Suggests damaged cable0.8%

- 0.8%


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In this recent example, one of several now, the link kept

dropping back to 100BASE-TX from 1000BASE-T

The link was tested for compliance to ISO/IEC Class EA

And showed a PASS with good margins


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The link was retested with the addition of

TCL: Transverse Conversion Loss

ELTCTL: Equal Level Transverse Conversion Transfer Loss

TCL and ELTCTL are mandated for lab testing, not field

testing in both ANSI/TIA and ISO/IEC standards

May wish to use as a troubleshooting tool


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Avoiding fiber failures

Get proactive


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Fiber Inspection

We all know how important it is

It is rare that calls to our Technical Assistance Center from

techs have ANY inspection equipmentbut they tell us they

have cleaned it

Cleaning without inspection can result in this:

Solvent pens are better than IPA


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Length test the fiber

You MUST test your reels 100%

Quick termination using

Mechanical splice or

Bare fiber adapter

OTDR (Length test) the cable

Any breaks will result in a shorter

length than expected

Failure to do so

Could result in pulling new cable

Mechanical Splice


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No length testing of fiber reel

6 fiber install, 1 fiber is brokenwhose fault was it?


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LED or VCSEL?

Near field image

LED VCSEL


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ANSI/TIA-526-14-B

No option to use a Vertical Cavity Surface Emitting Laser

(VCSEL) as a source, previous 526-14-A did allow them

VCSELs have a spectral width 0.47 nm

Measurement uncertainty associated with VCSELs isunacceptable with todays low loss components

Cabling vendors rejecting these results too


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What is a launch condition?

The light sources launch condition determines how and

where the light is distributed within the fiber

Source 1Over filled Source 3EF CompliantSource 2Under filled

CladdingCore


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To EF or not, that is the question

Current thinking on Encircled Flux

If I am not asked for it, then no

If it passes, no

If it fails, probably will look into it

This thinking is flawed

An under-filled launch condition will give an optimistic reading, so the

PASS may not actually be a PASS

Under filledOverfilled


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TIA-TSB-4979

Method 1: Launch Conditioner

Makes any LED source Encircled Flux

compliant

Users complain of bulkiness

Cost concerns Can be difficult to get hold of


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TIA-TSB-4979

Method 2: Matched source and test reference cord

Tester vendor specific

More elegant Significantly cheaper

EF


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Diagnosing fiber failures

Get proactive


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Tier 1 Negative loss

Caused by setting a reference as shown below

Cabling vendors / consultants are starting to reject

results if they think you are doing this, even if the

result is not negative, it will be optimistic

X


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Using an SC to LC adapter is the same as setting a reference

through a bulkhead adapter

SC

LC

Worlds shorted patch cord


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Reference without a bulkhead adapter in the middle

Requires equipment with interchangeable

adapters on the inputs


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The cracks are starting to show

If the 1550 nm loss is greater than the 1310 nm loss, you haveeither a crack or bend in the fiber

Normally found in The back of the connector The splice tray at the splice protector

VFL or OTDR required to locate it


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Lost test results

Test equipment is often shared between jobs

Sharing a memory card or thumb drive across multiple jobs

will result in missed testing / lost results

Tips:

Assign a memory card or thumb drive per job

Theyre cheaper than retesting

Do not delete anything off it until you have been paid

Dont leave them on the dashboard of the truck

Check your pockets before doing laundry

Careful what you put on there, I can recover EVERYTHING!


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Summary

Consider building a reference link, check your field tester

against it on a daily basis

Batch test twisted pair cables before installing

Investigate and understand time domain diagnostics for faster

fault resolution

Consider TCL and ELTCTL as diagnostic tools

Each technician should have their own fiber inspection

equipment with the appropriate tips

Stop setting a reference through a bulkhead adapter

Dont ignore warnings on the tester


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Summary

Any new fiber OLTS equipment must be EF compliant

Test the fiber reel before it is installedall fibers 100%

Get some more memory cards / thumb drives


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Thank you for your time

[email protected]

Date post:	02-Jun-2018
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