Testing and troubleshooting enterprise fiber-optic cabling Presenter: Neftali Usabal Fluke 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
ANSI/TIA-568-C.0-2 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) 100GBASE-SR10 (100 m, 1.9 db over OM3) 100GBASE-SR10 (150 m, 1.5 db over OM4) Limits are getting tighter, CPR and MPD no longer good enough
ANSI/TIA-526-14-A 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 (2003) 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!
Optical Test Equipment Summary Type of Test Equipment Investment Used For Required Tests For Visual VFL, Microscope, $300 - $4000 Verification Rarely Continuity, Polarity, Cleanliness Power & Attenuation Power Meter $1K -$5k Verification to manually determined loss budgets Sometimes as proxy for Tier 1 Power, loss, continuity, polarity Attenuation Testing (Tier 1) Optical LossTest Set (OLTS) $6K - $13K Certification to performance standards Always End -to end Loss, Continuity, length polarity & compares to performance standards OTDR (Tier 2) OTDR $8K - $17K Certification & Troubleshooting to ensure installation workmanship Typical Analyzes Events (splice & connector) by measuring reflectance
Fiber inspection and cleaning 12
#1 Problem: Dirt! Contaminated connector end-faces: Leading cause of fiber link failures Particles of dust and debris trapped between fiber end faces cause 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 13
Why Bother Inspecting End Faces? To Prevent Damage Debris will embed in glass when contaminated connectors are mated When embedded debris is removed, pit remains in glass as permanent damage Pits cause signal loss and back reflection Debris causes other damage such as chips and scratches 14
Inspection images Good Connector Fingerprint on Connector Real images as captured from the Fluke Networks Fiber Inspector Dirty Connector
COMMON MISCONCEPTIONS Protective caps keep end-faces clean - NO Caps are a source of contamination: moldrelease compound from manufacturing End-faces are NOT clean when they come pre-terminated from the factory in a sealed bag Canned air will blast away dirt - NO Is ineffective on smaller, static-charged particles Blows larger particles around rather than removing them Is ineffective on oils and compound contaminants Isopropyl alcohol (IPA) is the best solvent NO IPA does not work on non-polar contaminants 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 remove solvent Cleaning with a dry wipe will not dissolve contaminants and can generate static, attracting dust Proper handling and motion Apply gentle pressure with soft backing behind cleaning surface 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 Confidential Hands ON - Fiber Inspection Tap TOOLS Tap FiberInspector Focus the image with the knob on the probe Press to pause or enter the still mode
Company Confidential 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
Tier 1 Fiber Certification with OLTS Double Ended Test Absolute Loss measurement Compares Loss to industry standards Pass/Fail Results Other helpful Capabilities Length measurement Project/Loss budget Wizard Two fibers at a time Bidirectional testing Set Referencing Wizard
Managing Uncertainty 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
Impact of test reference cords 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 0.10 db 0.75 db 0.20 db 0.75 db 0.30 db 0.50 db
Setting a Reference What is done today Sadly, most folks are setting a reference this way? db 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
What is done today So you end up with this y db x db z db Measurement = x + y + z -? 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
What is done today Let s take an example 0.75 db 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
What is done today Let s take an example 0.1 db 0.3 db 0.3 db Issues Measurement = 0.3 + 0.1 + 0.3 0.75 = -0.05 db 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
What is done today ANSI/TIA describes this as Method A? db Not for enterprise cabling systems Used in long haul measurements Uncertainty of one connector not considered critical?
What is done today 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
Removed from INPUT port only 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
To the INPUT ports Connect known good cord
To the INPUT ports Connect known good cord
Connect known good cord How do I know if those cords are good?
Verifying the cords Connect them together using a singlemode adapter and measure the loss * ISO/IEC 14763-3 0.1 db for Multimode 0.2 db for Singlemode ANSI/TIA-568-C.0 0.75 db? * This can be up to 0.15 db for LC Cabling Vendors 0.50 db? Why not save this as proof of good test reference cords?
Test Reference Cord Values 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
Disconnect
Connect to the fiber optic link ANSI/TIA-568-C.0 0.75 db 0.75 db First and last connections 0.75 db All other connections 0.75 db
Launch conditions Diagrams shown to visualize the issue as best as possible Source 1 Over filled Source 2 Under filled
EF assessment improvement 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. Source 1 Over filled Source 2 Under filled
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 for implementing it
Practical implementation of Option 1 EF Use an external mode controller Replaces the mandrels
Practical implementation of EF Option 2 -Matched source and test reference cord
Tier 1 Fiber Certification At a minimum, use a mandrel This does not yield the controlled launch condition the industry desires that is Encircled Flux Don t use a VCSEL source Too much variability Not standards compliant Summary Consider investing in fiber optic test equipment that allows a 1 Jumper Reference reduced uncertainty Verify your Test Reference Cords Save the results and make it part of your documentation If Encircled Flux is a contractual requirement, or you care about getting as many passes as possible: Reference TIA/TSB 4979 EF Mode Controllers DTX-EFM2 CertiFiber Pro
OTDR TEsting 46
What is An OTDR? -OptiFiber Pro OTDR 5.7 inches touchscreen display Singlemode, Multimode and Quad modules Taptive gesture based user interface 10.6 x 5.0 x 2.5 inches EventMap 8-hour battery life
What Does An OTDR Do? OTDR Port Connector Fiber Under Test Directional Coupler Very Sensitive Photo Detector OTDR Two Laser Diodes Optical Fiber Electrical Color Display Processing & Control Sends pulses of light out Keeps checking for reflected light The farther the light goes, the more time it takes to come back (measures length) The farther the light goes, the more loss it encounters, so less comes back (measures fiber loss) When light hits a connection, an extra spike of light reflects back (finds connections) 48
OTDR in Action Loss Distance The OTDR measures reflected energy and NOT the transmitted light level. 49
OTDR Technology Rayleigh Scattering Fresnel Reflection 50
Rayleigh Scattering Scattering, (Rayleigh Scattering) occurs when transmitted 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. 51
Fresnel Reflection 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 rest continues out of the material. Coupling loss air gap causes loss of light transmitted 52
An air gap between the end faces of a fiber also cause Fresnel reflections to occur. What is reflectance?
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) Refl 10log P reflected It is a measure of the amount of power NOT reflected by a link. P incident Return Loss is the preferred term when characterizing an entire link Includes all connections and fiber It is always positive. Bigger is better (e.g. +35dB is better than +20dB) P ORL 10log P incident reflected
Why should you care? High reflectance causes increased Bit Error Rates (CRC errors) on the network
What Do OTDR Test RESULTS Look Like? 56
Test Example: Tier 2 (OTDR) Horizontal Cables X TR X X MC X Backbone Cables OTDR characterizes link details
EventMAP & EVENT Table from OTDR EventMap Event Table 58
EVENTMAP Easy to understand map of the physical 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 to previous event s loss
Typical OTDR TEST RESULT Reflection Backscatter 60
Reflective Event Connector 61
Loss Event Non-reflective event Splice or severe bend 62
End Event End of Fiber 63
Gainer Event Gainer 64 50 micron fiber connected to a 62.5 micron fiber
GHOST EVENT Ghosts 65
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 66
Dynamic Range Initial backscatter level at OTDR front connector db Measurement Dynamic Range Noise 0 0 Length 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. 67
Dead Zone A dead zone is like when your eyes need to recover from looking at the bright sun or the flash of a camera It can be reduced by using a lower pulse width, but it will decrease the dynamic range. 68
Two Types of Dead Zones Typically occurs in a trace whenever there is a connector The OTDR receiver goes blind from the strong reflection Includes duration of the reflection and recovery time for the receiver. Attenuation dead zone Event dead zone 69
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 0.6m @ 1310 nm, 3 ns, -50 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 OTDR where 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 3.6m @ 1310 nm, 3 ns, -50 db Reflectance 3.6 m @ 1550 nm, 3 ns, -50 db Reflectance
Using a LAUNCH AND TAIL Fiber Launch Fiber Tail Fiber Will give loss of the first connector Will give loss of the last connector 72
Launch & TAIL Fiber A must for measuring the loss of the first 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 launch fiber 73
Launch Fiber Compensation 74
Getting to Systems Acceptance Verification Testing Typically performed after MC, IC and / or HC connector installation Improves attenuation testing time Attenuation Testing Final System Verification Certifies Loss is within Performance Standard requirements OTDR Testing Tests links and point discontinuities
Support Resources Knowledge Base: http://myaccount.flukenetworks.com/f net/en-us/supportanddownloads/kb Technical Assistance Center 24 x 7 assistance: support@flukenetworks.com USA: 1-800-283-5853 Resources for Experts Designers: http://www.flukenetworks.com/experti se/role/architects-consultants- Designers Installers: http://www.flukenetworks.com/experti se/role/guide-to-contract-installersand-installation