OTDR “How To Demo” Training Jody Frey CES jody.frey@cesreps.coom 763-772-8111

Introducing the TB/MTS-2000 and Understanding Key OTDR Parameters

Introduction the TB/MTS-2000 OTDR Most important fiber tester for installation, maintenance & troubleshooting T-BERD/MTS 2000 indoor/outdoor screen Locate event / impairments: Physical distance in m, Km, Ft, KFt, Mi Detect impairments: Splice, bends, connectors, breaks Measure loss: Fiber attenuation Loss of connector, splice Return loss & Reflectance Trigger alarms: User defined thresholds Easily generate report: Simplified pdf report generation If you can only afford one piece of test gear in your network (and it’s not a small LAN), the OTDR is the tool you will need. It will do almost everything you need to fundamentally evaluate the fiber (except for advanced test, such as PMD, CD)

Embed built-in essential fiber testing tools TB-2000 Options MICROSCOPE TALKSET POWERMETER VFL P-5000/5000i Embed built-in essential fiber testing tools Measure optical power with built-in broadband power meter Prevent fiber crossing with built-in VFL Communicate at no cost and out of cell phone coverage zone with built-in optical talk set (optional) Certify fiber end faces with instant IEC Pass/Fail analysis using P5000i inspection probe

Initial Reflection and Noise Dynamic Range (Optical) OTDR KEY PARAMETERS Initial Reflection and Noise Dynamic Range (Optical) SNR=1 98% Noise Measurement Range (Software Analysis) Pulsewidth Reflection (Fresnel) Deadzone Event Attenuation Loss (Attenuation) Splice ORL

Example of an OTDR trace How does it work ? OTDR injects light pulse & analyzes the backscatter and reflected signal Received signal is plotted into a backscatter X/Y display in dB vs. distance Analyzes events to populate table of results OTDR Block Diagram Example of an OTDR trace OTDR’s are similar in principle to: Copper TDR Radar Sonar Shoot from one end collect reflected signal tie round trip time to one way distance. Parameters

What does an OTDR Measure ? Distance The OTDR measurement is based on “Time”: Measure round trip time of pulse Known: Speed of light in Vacuum Index of Refraction of Fiber Calculate distance Fiber distance = Speed of light (vacuum) X time 2 x IOR Converts time (round trip time for signal to go out and backscatter return) Parameters

Key OTDR Setup Parameters for Manual Operation Index of Refraction (IOR) The IOR converts time, measured by the OTDR, to distance, which is displayed on the trace Entering the appropriate value into the OTDR will ensure accurate length measurements for the fiber. You may also need to set the IOR There is more fiber in cable (fiber length) than there is cable (cable length). This is called an overlength factor. You can optimize the distance accuracy of the OTDR by referencing a known cable length to the OTDR and set the IOR to match the physical reference.

Dynamic Range & Injection Level Dynamic Range determines the observable length of the fiber & depends on the OTDR design and settings Injection level is the power level in which the OTDR injects light into the fiber under test Poor launch conditions, resulting in low injection levels, are the primary reason for reductions in dynamic range, and therefore accuracy of the measurements Effect of pulse width: the bigger the pulse, the more backscatter we receive The higher the dynamic range the further the OTDR will see. The higher the dynamic range, the more expensive the OTDR will be. For best value determine the right module for the job.

Pulse width Pulse Width Controls the amount of light injected into the fiber A short pulse width enables high resolution and short dead zones, but limited dynamic range A long pulse width enables high dynamic range but less resolution and longer dead zones 5ns 1µs So, if you go to manual, there are three key parameters that you need to set: The first is pulse width. Short Pulse: More Resolution Shorter Dead Zones Less Dynamic Range More Noise Long Pulse: Less Resolution Wider Dead Zones More Dynamic Range Less Noise 100ns Parameters

Key OTDR Setup Parameters for Manual Operation Acquisition Time (Averaging) Length of time the OTDR takes to acquire and average the data points Increasing acquisition time improves the dynamic range w/o affecting the resolution or dead zones. 5s 30s In addition you need to set the averaging time. Today 15-20 seconds is most common, but sometimes you may want to use a shorter pulse to see more detail and you may need to average longer to get a cleaner trace. 20s

What does an OTDR Measure ? Attenuation (also called fiber loss) Expressed in dB or dB/km, this represents the loss, or rate of loss between two events along a fiber span The further the round trip of the backscatter the weaker the signal.. The X axis plots distance & Y axis plots dB signal level It appears logically as a decreasing signal left to right over distance. Parameters

What does an OTDR Measure ? Event Loss Difference in optical power level before and after an event, expressed in dB An event is either something that was placed on purpose (splice, connector) Or something that has happened to the fiber (bend) Depending upon the event, It’s going to look something like the above Fusion Splice or Macrobend Connector or Mechanical Splice Parameters

What does an OTDR Measure ? Reflectance Ratio of reflected power to incident power of an event, expressed as a negative dB value The higher the reflectance, the more light reflected back, the worse the connection A -50dB reflectance is better than -20dB value Reflectance relates to a specific event . This is especially critical in high speed networks (10G+) Or in applications that use high power lasers (RF Video overlay in FTTH) Reflectance can cause signal degradation and needs to be managed. Parameters

What does an OTDR Measure ? Optical Return Loss (ORL) Amount of light reflected back from a feature OTDR is able to measure not only the total ORL of the link but also section ORL Attenuation (dB) ORL is similar to reflectance, but instead of a single event, ORL is a measure of a section or span of overall reflected signal. ORL of the defined section Distance (km) Parameters

How to interpret an OTDR Trace Do step you through interpretation of an OTDR trace, we’re going to utilize content from one of our Wall posters we’ve recently developed. It’s called “Understanding OTDRs”. ILater in the Webex we’ll show you how you can get your own poster. So here you see an OTDR trace w/ lots of “events”. Let’s take a closer look at each one. Parameters

Connection between the OTDR and the patch cord or launch cable Front End Reflection Connection between the OTDR and the patch cord or launch cable Located at the extreme left edge of the trace Reflectance: Polished Connector ~ -45dB Ultra-Polished Connector ~ -55dB Angled Polished Connector up to ~ -65dB Insertion Loss: Unable to measure At the very beginning of the OTDR trace you see the first connection.(reflective) Notice the spike (reflection) then a drop back down to a steady signal level. Parameters

Connector A connector mechanically mates 2 fibers together and creates a reflective event or an open fiber end face can create a reflective event (-14dB for flat polish) Reflectance: (A -50dB reflectance is better than -20dB reflectance value) Polished Connector ~ -45dB Ultra-Polished Connector ~ -55dB Angled Polished Connector up to ~ -65dB Insertion Loss: ~ 0.5dB (~0.2dB w/ very good connector) A connector causes a reflection (air gap) which. An angled connector will have a much lower spike than a non-angled (PC type) Parameters

Insertion Loss: < 0.05dB Fusion Splices A Fusion Splice thermally fuses two fibers together using a splicing machine Reflectance: None Insertion Loss: < 0.05dB A “Gainer” is a splice gain that appears when two fibers of different backscatter coefficients are spliced together (the higher coefficient being downstream) Fusion splices are the standard method of splicing fibers today. You won’t see them as much in LANs as you will in public networks.due to distances. Reflectance: None Insertion Loss: Small gain Parameters

Dead Zones Attenuation Dead Zone (ADZ) is the minimum distance after a reflective event that a non-reflective event can be measured (0.5dB) In this case the two events are more closely spaced than the ADZ, and shown as one event ADZ can be reduced using shorter pulse widths Event Dead Zone (EDZ) is the minimum distance where 2 consecutive unsaturated reflective events can be distinguished In this case the two events are more closely spaced than the EDZ, and shown as one event EDZ can be reduced using shorter pulse widths At some point you’ve probably heard people talk about dead zones. Where w/ your mobile phone, a dead zone is a spot where you can’t hear, an OTDR dead zone is an area where you cannot see true signal. It’s caused by reflective events (connector, mechanical splice) Within the definition of Dead Zone, there are two categories: ADZ & EDZ (above)

Fusion Splices Direction A-B Direction B-A Biggest challenge w/ OTDR’s here is getting the loss of the event accurate. If you need optimum accuracy you’ll need to shoot both directions.

Insertion Loss: Varies w/ degree of bend & wavelength Macrobend Macrobending results from physical bending of the fiber. Bending Losses are higher as wavelength increases. To distinguish a bend from a splice: two wavelengths are used (typically 1310 & 1550nm) Here we’re only covering Macrobends; but… You’ll also here the two terms Macrobend & Microbend - Same result, but different causes… Macrobending loss refers to loss from physical bending of the fiber Microbending loss is caused by pressure resulting in changing the physical shape fo the glass at a particular spot (core deformation) Reflectance: None Insertion Loss: Varies w/ degree of bend & wavelength Parameters

Mechanical Splice A Mechanical Splice mechanically aligns two fibers together using a self-contained assembly. Reflectance: ~ -35dB Insertion Loss: ~ 0.5dB Don’t see too many of these anymore. Looks like a connector because it’s a mechanical connection w/ an air gap. This has been replaced for the most part by the fusion splice. Parameters

A Fiber End or Break occurs when the fiber terminates. The end reflection depends on the fiber end cleavage and its environment. Reflectance: PC open to air ~ -14dB APC open to air ~ - 35dB Insertion Loss: High (generally) An OTDR cannot tell you whether the end of the fiber is the real end or a cut or break. The signals look the same, so here you have to use your knowledge of the network. ”How long is it supposed to be?” “ “Am I shooting the correct fiber?” Parameters

Reflectance: Lower than echo source Insertion Loss: None Ghosts A Ghost is an unexpected event resulting from a strong reflection causing “echoes” on the trace When it appears it often occurs after the fiber end. It is always an exact duplicate distance from the incident reflection. Normally seen after the end of fiber. Ghosts are what they sound like (unless you believe in Ghosts) The are artifacts that show up on the trace that aren’t really there. But you can spot a ghost if you know what to look for… Now OTDRs have Ghost detect features that you can use to help identify them. Reflectance: Lower than echo source Insertion Loss: None Parameters

Bending Large noticeable bends and microscopic irregularities can both attribute to loss in a fiber. Macrobending Microbending Parameters

Typical Attenuation Values 0.2 dB/km for singlemode fiber at 1490,1550 and 1625 nm 0.35 dB/km for singlemode fiber at 1310 nm 1 dB/km for multimode fiber at 1300 nm 3 dB/km for multimode fiber at 850 nm 0.05 dB for a fusion splice 0.3 dB for a mechanical splice Connector pair loss 0.5 dB for a singlemode connector pair (FOTP-34) 0.75dB for a multimode connector pair PON Splitters/monitor points Splitter 1x2 1x4 1x8 1x16 1x32 Best Loss dB 3 6 9 12 15 Max. Excess Loss dB 1 2 4 Typical Loss dB 7 11 19 Parameters

Install Smart Link Mapper (aka SLM) Modern way of viewing trace

USB Stick SLM Upgrade Instructions 6/6 Ensure SLM Enabled: Open Trace and select SmartLink radio button (on right) SmartLink View opens, Event View available and Trace View to return to OTDR trace

What does a typical OTDR tester look like TB-2000 OTDR Dave intros the webinar and intros me What does a typical OTDR tester look like

Front Panel Controls

Top and Right-side ports

QUAD (SM + MM) OTDR Module Combined SM and MM wavelengths in a single OTDR module Applications: Cell Backhaul/Switch/and FTTA (MM+SM) Short/Medium Range Distances in SM (100 feet to 60 miles) Short dead zones(for both MM & SM) to better locate close events Light Source and Power Meter capability on both SM & MM OTDR ports ONE BUTTON TEST

Expert OTDR Mode

Expert OTDR SETUP To simplify demo, choose laser, select Alarm and Press Test Auto softkey For fun, tap each label change settings to see effect. Choose Laser and Auto Set Smart Acq. (Yes) for Med/Long fibers Set Otdr Connector Test (Yes & Abort) Enter Launch Cable values Tap Index of Refraction & select Tap distance unit Set Otdr Connector Meas (Yes) Setup configurations can be saved into a file for future re-use

Understanding Expert OTDR RESULTS Screen – Expert OTDR mode Select trace Highlight is current view Filename (OTDR Result/SETUP) Wavelength, Pulsewidth, Fiber # Battery Level Date/Time (System Settings/Regional) Test Direction Thumbnail view Full Trace Red box Zoom view on Grid Fiber Trace Current trace is Green Live Traffic indicator Y-axis = Loss dB Total # events current view Full Span Return Loss (ORL) Softkeys – 6 total Event Table Current trace view X-axis – distance Change Units (SETUP/Measurm’t) Select Test Mode TABS (Activated on HOME)

SMART OTDR Mode Smart in that the test set does the work

SMART OTDR RESULTS Screen Event Table/Display size remain the same NO ALARM Threshold Setup ENTER key (full view or auto-zoom view) Zoom softkey – full zoom or at selected cursor(s) 1x or 2x Limited Setup capabilities Fiber flagged with X as failing due to a bad splice with 0.291dB loss, located at 0.30126 mile of fiber

Fiber Basics

Optical Fiber Types 2 types: Singlemode Multimode

Cross section of an Single Mode optical fiber Fiber Structure consists of a glass core, an outer protective glass cladding, and a buffer or coating Buffer Cladding Core 250 125 9 - What is fiber characterization? A series of tests to perform network base-lining on a fiber network. Fiber characterization mainly consists of the 5 following tests: - Optical Insertion Loss - Optical Return Loss - Optical Time Domain Reflectometry traces - Chromatic Dispersion testing - Polarized Mode Dispersion testing Side Front

Common Connector Types SC Commonly referred to as Sam Charlie ST Commonly referred to as Sam Tom FC Commonly referred to as Frank Charlie LC Commonly referred to as Lima Charlie

Connector Configurations PC or UPC vs APC SC - PC SC - APC

Loss Basics

Focused On the Connection Bulkhead Adapter Ferrule Fiber Fiber Connector Alignment Sleeve Alignment Sleeve Physical Contact Fiber connectors are widely known as the WEAKEST AND MOST PROBLEMATIC points in the fiber network.

What Makes a GOOD Fiber Connection? The 3 basic principles that are critical to achieving an efficient fiber optic connection are “The 3 P’s”: Perfect Core Alignment Physical Contact Pristine Connector Interface Light Transmitted Core Cladding CLEAN

What Makes a BAD Fiber Connection? CONTAMINATION is the #1 source of troubleshooting in optical networks. A single particle mated into the core of a fiber can cause significant back reflection, insertion loss and even equipment damage. Visual inspection of fiber optic connectors is the only way to determine if they are truly clean before mating them. Light Back Reflection Insertion Loss Core Cladding DIRT

Illustration of Particle Migration 11.8µ 15.1µ 10.3µ Core Cladding Actual fiber end face images of particle migration Each time the connectors are mated, particles around the core are displaced, causing them to migrate and spread across the fiber surface. Particles larger than 5µ usually explode and multiply upon mating. Large particles can create barriers (“air gap”) that prevent physical contact. Particles less than 5µ tend to embed into the fiber surface creating pits and chips.

Types of Contamination A fiber end-face should be free of any contamination or defects, as shown below: Simplex Ribbon Common types of contamination and defects include the following: Dirt Oil Pits & Chips Scratches

Contamination and Signal Performance Fiber Contamination and Its Affect on Signal Performance 1 CLEAN CONNECTION Back Reflection = -67.5 dB Total Loss = 0.250 dB 3 DIRTY CONNECTION Clean Connection vs. Dirty Connection This OTDR trace illustrates a significant decrease in signal performance when dirty connectors are mated. Back Reflection = -32.5 dB Total Loss = 4.87 dB

Inspect Before You Connectsm Follow this simple “INSPECT BEFORE YOU CONNECT” process to ensure fiber end faces are clean prior to mating connectors. INSPECT CONNECT Is it clean? NO YES CLEAN

IEC 61300-3-35 Acceptance Criteria These criteria are designed to guarantee a common level of performance Separate criteria for different connector types SM-UPC (RL>45db) SM-APC SM-PC (RL>26dB) MM Multi-fiber Example of Pass/Fail Criteria (SM-UPC) Core Zone Cladding Zone Contact Zone ZONE NAME SCRATCHES DEFECTS A. CORE (0–25μm) None CLADDING (25–120μm) No limit <= 3μm None > 3μm No limit < 2μm 5 from 2–5 μm None > 5μm ADHESIVE (120–130μm) No limit CONTACT (130–250μm) None => 10μm Science & Statistics - This criteria is tied to performance We determined zone Emphasize the difficulty of subjective inspection The standards body make it as simple as they could……but it is still hard Criteria is a guarantee…..adhering to it is a different story