1. OTDR “How To Demo” Training
Jody Frey
CES

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

3. 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)

4. 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

5. 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

6. 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

7. 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

8. 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.

9. 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.

10. 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

11. 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 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

12. 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

13. 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

14. 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

15. 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

16. 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

17. 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

18. 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

19. 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

20. 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)

21. 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.

22. 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

23. 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

24. 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

25. 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

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

27. 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

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

29. 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

30. 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

31. Front Panel Controls

32. Top and Right-side ports

33. 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

34. Expert OTDR Mode

35. 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

36. 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)

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

38. 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 mile of fiber

39. Fiber Basics

40. Optical Fiber Types
2 types:
Singlemode
Multimode

41. 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

42. 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

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

44. Loss Basics

45. 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.

46. 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

47. 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

48. 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.

49. 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

50. Contamination and Signal Performance
Fiber Contamination and Its Affect on Signal Performance 1
CLEAN CONNECTION
Back Reflection = dB
Total Loss = 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 = dB
Total Loss = 4.87 dB

51. 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

52. 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