jody frey ces [email protected] 763-772-8111 otdr “how to demo” training

Jody [email protected]

OTDR “How To Demo” Training

mailto:[email protected]

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

© 2012 JDS Uniphase Corporation | JDSU CONFIDENTIAL AND PROPRIETARY INFORMATION 3

Introduction the TB/MTS-2000 OTDR

Most important fiber tester for installation, maintenance & troubleshootingT-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


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)

• SNR=1• 98% Noise

Measurement Range (Software Analysis) Pulsewidth Reflection (Fresnel) Deadzone

• Event• Attenuation

Loss (Attenuation) Splice ORL

OTDR KEY PARAMETERS


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

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

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.


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


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

Short Pulse:• More Resolution• Shorter Dead Zones• Less Dynamic Range• More Noise

5ns

1µs

100ns Long Pulse:• Less Resolution• Wider Dead Zones• More Dynamic Range• Less Noise

Parameters


5s 30s

20s

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.



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

Parameters



Event LossDifference in optical power level before and after an event, expressed in dB

Fusion Splice or Macrobend

Connector orMechanical Splice

Parameters


ReflectanceRatio 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


Parameters



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

Distance (km)

Att

enu

atio

n (

dB

)

ORL of the defined section

Parameters


How to interpret an OTDR Trace

Parameters


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

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)

Parameters


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)

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


Fusion Splices

Direction A-B Direction B-A


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)

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

Parameters


Fiber End or Break

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)

Parameters


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.

Reflectance: Lower than echo source

Insertion Loss: None

Parameters


Bending

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 1 2 3 4

Typical Loss dB 4 7 11 15 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


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

Choose Laser and AutoSet Smart Acq. (Yes) for Med/Long fibersSet Otdr Connector Test (Yes & Abort)Enter Launch Cable values

To simplify demo, choose laser, select Alarm and Press Test Auto softkey

For fun, tap each label change settings to see effect.

Tap Index of Refraction & selectTap distance unitSet Otdr Connector Meas (Yes)

Setup configurations can be saved into a file for future re-use


Understanding Expert OTDR RESULTS Screen – Expert OTDR mode

Filename (OTDR Result/SETUP)

Date/Time (System Settings/Regional)

Thumbnail view Full TraceRed box Zoom view on Grid

Y-axis = Loss dB

Wavelength, Pulsewidth, Fiber #

Battery Level

Softkeys – 6 total

Select trace Highlight is current view

Event Table Current trace view

Total # events current viewFull Span Return Loss (ORL)

Select Test Mode TABS (Activated on HOME)

X-axis – distanceChange Units (SETUP/Measurm’t)

Test Direction

Fiber TraceCurrent trace is GreenLive Traffic indicator

SMART OTDR ModeSmart 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


9125250

Cross section of an Single Mode optical fiber


Common Connector Types

SC Commonly referred to as Sam Charlie

FC Commonly referred to as Frank Charlie

ST Commonly referred to as Sam Tom

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

Fiber Connector

Alignment Sleeve

Alignment Sleeve

Physical Contact

FiberFerrule

Fiber connectors are widely known as the WEAKEST AND MOST

PROBLEMATIC points in the fiber network.


What Makes a GOOD Fiber Connection?

Perfect Core Alignment

Physical Contact

Pristine Connector Interface

The 3 basic principles that are critical to achieving an efficient fiber

optic connection are “The 3 P’s”:

Core

Cladding

CLEAN

Light Transmitted


What Makes a BAD Fiber Connection?

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.

CONTAMINATION is the #1 source of troubleshooting in optical networks.

DIRT

Core

Cladding

Back Reflection Insertion LossLight


Illustration 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.

11.8µ

15.1µ

10.3µ

Actual fiber end face images of particle migration

Core

Cladding


Types of Contamination

A fiber end-face should be free of any contamination or defects, as shown below:

Common types of contamination and defects include the following:

Dirt Oil Pits & Chips Scratches

Simplex Ribbon


Contamination and Signal Performance

Fiber Contamination and Its Affect on Signal PerformanceCLEAN CONNECTION

Back Reflection = -67.5 dBTotal Loss = 0.250 dB

1

DIRTY CONNECTION

Back Reflection = -32.5 dBTotal Loss = 4.87 dB

3

Clean Connection vs. Dirty Connection

This OTDR trace illustrates a significant decrease in signal performance when dirty connectors are mated.


Inspect Before You Connectsm

Follow this simple “INSPECT BEFORE YOU CONNECT” process to ensure

fiber end faces are clean prior to mating connectors.

CONNECTINSPECT

CLEAN

Is itclean?

NO YES


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

Core Zone

Cladding Zone

Contact Zone

ZONE NAME SCRATCHES DEFECTS

A. CORE (0–25μm) None None

B. CLADDING (25–120μm)

No limit <= 3μmNone > 3μm

No limit < 2μm5 from 2–5 μmNone > 5μm

C. ADHESIVE (120–130μm)

No limit No limit

D. CONTACT (130–250μm)

No limit None => 10μm

Example of Pass/Fail Criteria (SM-UPC)

jody frey ces [email protected] 763-772-8111 otdr “how to demo” training

Documents

proprietary information

otdr traceparameters

key otdr parameters

cable fiber length

key otdr setup parameters

time round trip time

distancethe otdr measurement

physical distance