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May 2018

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FOA Newsletter - Features

In This Issue - (INDEX)

Click on "RETURN TO INDEX " after each section to return you to this INDEX so you can find things easier.


FOA Trainers Get Around
-Dohn HS Cincinnati
-Northern Canada
-Traffic Engineers in Mesa Arizona
Directional Boring in St. Louis
Proof Some Techs Need More Training
What We Learned From A Wireless Conference
Landline Phones Continue Decline
Tapping Fiber In German Data Center
FOA Testing Video Microscope
10M Single Pair Ethernet
Conference on Plastic Optical Fiber

Important tech info repeated from last month while we add it to the FOA Guide:
Power Budgets/Loss Budgets,
   Setting "0dB" References And Modal Distribution
OTDR Bi-directional Confusion
How "Fast" Is FIber?
Dust Transfer Between Connectors

Recycling Fiber Optic Cable
Bad Times For Homes And Poles
What Does A FTTH ONT Look Like Today?
Things We've Seen
Panduit OptiCam2 Tool
Color Codes For 16-fiber MPO
Fiber Optic Sensor Market
Plus some really interesting technical questions discussed in depth


OLANs - Optical LANs
OTDRs - more info
OSP Civil Works  
More to read in Worth Reading and Q&A

Membership & Certification  

CFOT Total


FOA Facts - about the organization

New @ FOA  
Fiber U - free online self-study courses
Publications: FOA Textbooks, NECA/FOA 301 Installation, eBooks
More "Quickstart Guides" - OTDRs
 videos: New FOA YouTube Videos
Online Reference Guide: Many new pages 
Tech Topics: More online information
Certification: New FOA OSP Certification
FOA Schools: New schools and programs
Events: Webinars, Conferences and Shows of Interest To Fiber Techs  
Webinars: Online seminars on useful topics 
Q&A: What you are asking the FOA?
Product News - New stuff
Worth Reading: News from around the world
Download This - Good applications material online

Like Crossword Puzzles? Try These.

DIG SAFE - Call 811 before you dig!

JobsCurrent openings for Cable Techs, Fiber Splicers, etc.
Also see FOA Jobs Web Page and FOA on FOA on LinkedIn
The FOA Jobs Web Page has been updated and a new page added on Using your FOA Training/Certification to Find the Right Job in Fiber Optics

Where Are The Jobs In Fiber Optics? FOA talks about all the applications for fiber optics, what jobs involve and the qualifications for the workers in the field in this YouTube video.

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The Archives: Past Issues.
Use these links to read past issues or use FOA's  Custom Search to look for specific topics on our website.
1/18, 2/18, 3/18, 4/18, 5/18,
1/17, 2/17, 3/17, 4/17, 5/17, 6/17, 7/17, 8/17, 9/17, 10/17, 11/17, 12/17 
1/16, 2/16, 3/16,  4/16, 5/166/167-8/16, 9/16, 10/16, 11/16, 12/16     
1/15, 2/15, 3/15, 4/15, 5/15, 6/15, 7/15, 8/15, 9/15 , 10/1511/15 , 12/15
1/14, 2/14, 3/14, 4/14, 5/14, 6/14, 7/14, 8/14, 9/14, 10/14, 11/14, 12/14 
1/132/13, 3/13, 4/13, 5/13, 6/13, 7/13, 8/13, 9/13, 10/13, 11/1312/13 
1/12 , 2/12, 3/12, 4/12, 6/12, 7/12, 8/12, 9/12, 10/12, 11/12, 12/12   
1/11 ,  2/11,  3/11,  4/11,  6/11, 7/11, 8/11,  9/11, 10/11, 11/11,  12/11,  
1/10 ,  2/10, 3/10,  4/10,   05/10,  07/10, 08/10,  09/10,  10/10, 11/10 
1/09 ,  2/09,  3/09, 04/09,  05/09,  07/09, 08/09, 09/09, 10/09, 11/09,  12/09
1/08 , 2/08, 3/08, 4/08, 5/08,  6/08, 7/08, 8/08, 09/0810/08, 11/08,  12/08 
12/07 , 11/07, 10/07, 09/07, 08/07, 07/07, 06/07, 05/07, 04/07, 03/07, 2/07, 1/07
12/06 , 11/06, 10/06, 09/06, 8/06, 7/06, 6/06, 5/06, 4/06, 3/06, 2/06, 1/06,
12/05 ,11/05, 10/05, 09/05, 08/05, 07/05, 6/05, 5/05, 4/05, 2/05, 01/05,
12/04 , 10/04, 9/04, 8/04, 7/04, 6/04, 5/04, 4/04, 3/04, 1/04,
12/03 , 11/03 10/03 9/03, 8/03, 7/03, 6/03, 3/03, 10/02 , 8/02, 5/02
Current Issue of FOA Newsletter

The FOA CFOT® (Certified Fiber Optic Technician) and Fiber U® (the FOA online self-study program) are registered trademarks of the FOA.
FOA Guide
Want to know more about fiber optics? Study for FOA certifications? Free Self-Study Programs are on "Fiber U®." Looking for specific information? Here's the largest technical reference on the web: The FOA Online Fiber Optic Reference Guide.

Free online self-study programs on many fiber optics and cabling topics are available at Fiber U, FOA's online web-based training website.

 FOA Reference Books
Available Printed or eBooks
The fiber book is available in Spanish and French

FOA Reference Guide to Fiber Optics book FOA Reference Guide to Premises Cablng book FOA Reference Guide to OSP Fiber Optics book FOA Reference Guide to Fiber Optics book
FOA Reference Guide to Fiber Optic Network Design book FOA Book on Fiber Optic Testing FOA Outside Plant Fiber Optics Construction Guide

Lennie and Uncle Ted's Guides are now also available as free iBooks on iTunes.
Lennie Lightwave's Guide To Fiber Optics   Uncle Ted's Guide to Premises Cablling
Click on any of the books to learn more.
Fiber Optic Safety Poster to download and print

FOA Videos on videos

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FOA Trainers Get Around

Last month we focused on things instructors learn while training. in that case training instructors who questioned us a lot more than novice techs generally do. This month we'll look at some of the training our instructors give that illustrate the goal of the FOA - "to promote professionalism in fiber optics through education, certification and standards."

FOA trainers show up at lots of interesting locations to train fiber optic and cabling techs and often instructors.Often they participate in "pro-bono" activities in their communities or when working with other organizations to assist them in building their training programs.

Below you will find some interesting stories of FOA training that make us as an organization proud of our schools and instructors.

Dohn Community High School Recognizes Allied IT, Techtricians, and The Fiber Optic Association at a "22+" Graduation Brunch

Dohn Community High School in Cincinnati, Ohio is a tuition free public charter school whose goal is to provide a high school program in a safe, disciplined and caring environment.  They have implemented the "22+ Program."  The 22+ program at Dohn supports individuals over the age of 22 to achieve their goal of obtaining a high school diploma along with courses that will help develop a career pathway.

FOA Board Member Tom Collins through his company Techtricians provided FOA CFOT certification training to a class of 22+ students at Dohn recently. Dohn recognized the contributions of Tom and the accomplishments of the students at a graduation brunch on May 22.

(L-R) Levar Wilson, Tom Collins of Techtricians, Shamell Saunders, Mrs. Saunders, Dan Greene of Allied IT 

Tom feels strongly the way we have often trained people is not effective and has put us globally behind in productivity. We should learn from the past and move forward.  The "Critical Skills” needed for future workers are; attendance, the 3r’s, computers skills, team work, and problem solving.  However, there is one big key component missing, “Mentorship”.

Mentorship is the partnership between the student, training provider, and employer. Each has their own set of responsibilities. The outcome of this mentorship is a customized training for the required skills needed in the workforce and filling the employers need for a highly trained global workforce.

Three unique entities formed a mentor partnership for this training; Dohn Community School, Allied IT Wiring (FOA Corporate Sponsor and CPCT & CFOT certificated techs) and Techtricians. The first graduate of this mentor partnership is Shamell Saunders who is employed by Allied IT Wiring. Allied IT Wiring is an FOA Corporate Member that already employs techs certified by the FOA.
Building upon this success, Techtricians also awarded a FOA CFOT scholarship to Levar Wilson.

Training In The Frozen North Of Canada

Bill Graham, FOA Board Member from the Toronto, Canada area, sold his company Mississauga Training Consultants several years ago and quit training techs on a regular basis but has been training new instructors in Canada for FOA. You might remember Bill from earlier stories about his training in the North of Canada - including a trip on a vintage DC-3 airliner to one training site!

Bill was recently in Winnipeg, Manitoba training at Broadband Communications North.

This group has funding initially to train technicians. Initially they will hire 40 techs to start installing thousands of miles of fiber through the north of Manitoba to serve at least 50 remote communities.   Broadband Communications North has started building a new training center. They will also start their own ISP (Internet Service Provider) and produce their own programming.

This is just the start - Bill expects to see similar projects in all northern areas of the Canadian provinces.

BCN Winnipeg

CFOT  Graduating Class, May 25th., Winnipeg,  Broadband Communications North Inc.
Left to right: Frank Parent, Georgi Mihaylov, Olaide Aladatan, Daniel Jebb, Ken Sanderson, Grace Mbawala

Arizona Department of Transportation Techs

And a view of what an "intelligent traffic control center" looks like.

FOA also recently trained a class of IMSA technicians from the Arizona Department of Transportation at the  facilities of the city of Mesa, Arizona. IMSA is the International Municipal Signalling Association, the professional society of traffic and city engineers that is now a FOA training and certification partner. FOA's Jim and Karen Hayes did this training as well as an earlier session for Nevada DOT personnel in Reno to help kick off the FOA/IMSA partnership on the West Coast.

The real treat for us was seeing the control room of the Mesa traffic department. During an afternoon break, we were invited into the control room and the techs working there showed us how their state-of-the-art system worked.


MESA has a system connected on fiber that includes video at intersections and smart, adaptive traffic signals. While in the control room, we discussed the city infrastructure to support these systems and how the city is looking to a future of challenges, like supporting autonomous cars.


The wall of 24 video screens allows techs to view intersections around the city of Mesa. New high-resolution cameras provide amazing detail of the areas covered by video. Traffic signals are programmed to adopt to traffic patterns, such as when a local college has classes ending in the mid-afternoon.

Directional Boring In St. Louis

FOA instructors and many of our CFOTs send us photos of things they see as they travel around. Here are some interesting photos from a directional boring job being done near the home of FOA instructor Milt Murry in St. Louis.

St Louis directional boring

The contractor is boring to install new ducts for a telco installation.

St Louis directional boring

While boring, another tech is using locating equipment to follow the boring and look for other underground services in the same area. This can prevent a common occurrence, puncturing water or sewer pipes when boring.

St Louis directional boring

A truck loaded with plastic fiber duct ready for installation.


There's more below....

.. plus some really interesting technical questions discussed in depth

Proof That More Fiber Techs Need Training And Certification


From CommScope poll on Twitter

What We Learned From Visiting A Wireless Conference

FOA recently attended the WIA's Connect(X) conference in Charlotte, NC. This was the first wireless show we'd attended in over a year and the topics of conversation were similar to last year - 5G topped the list. We attended several tech sessions and our takeaway from one was the answer to an attendees question to a speaker: "When can we expect a standard for 5G." The answer was revealing: "5G is not a standard, 5G is a goal."

If you search the web for cellular standards, you will probably end up at a Wikipedia page called "Comparison of Mobile Phone Standards." It's an interesting history of the development of cellular systems. Nothing on that page refers to 5G, but there is a page on 5G that starts off saying "This article is about proposed next generation telecommunication standard. 5th-Generation Wireless Systems (abbreviated 5G) is a marketing term."

Generally we don't recommend using Wikipedia for technical information because it is too often edited for commercial bias, (that's why we created the FOA Guide,)  but in this case the candor is refreshing.

Zinwave  Ericsson DAS

As we toured the trade show exhibits, we did see something new, this "Standalone Small Cell" from Zinwave. What's notable, is that like a similar device we saw last year from Ericsson that saw at the IWCE wireless meeting and we reported on in the June 2017 FOA newsletter, it looks similar to a WiFi wireless access point including Gigabit Ethernet interfaces to standard Category-rated copper cabling. DAS, it seems is migrating to operating off Cat 6/Cat 6A in a structured cabling system. Since most offices need both cellular (small cell or DAS) and WiFi, this makes sense.

When we tried to find a link to this Zinwave device on the company website and could not find it, we found something even more interesting on a page called "Cellular As A Service": Unfortunately, carriers are no longer spending on in-building commercial cellular coverage in the way they used to. That means building owners—whether they are in commercial real estate, healthcare, hospitality, or the enterprise—are now having to find and fund the solution themselves, and it’s not easy. It’s difficult to budget for the kind of capital outlay needed to deploy an in-building connectivity solution.

This may indicate a movement to make indoor cellular more accessible using small cells replacing DAS. We've been told that DAS is a declining market because most of the large public areas like sports arenas and convention centers have been done. Enterprise DAS has not been as big but if small cells on LANs, similar to WiFi, becomes cost effective - and at least one person told us it would be - then we are looking at a change in enterprise networks.

Wireless At FOA: This addition of cellular wireless to WiFi and of course the usual fiber or copper Ethernet connectivity expected of a corporate network is something we've seen before, and it's the reason FOA expanded it's course offerings and certifications to include a general "Fiber For Wireless" programs. We now offer a free
"Fiber For Wireless" program on Fiber U, a curriculum for our schools to teach, and of course a page on the FOA Guide.

Recommended Reading: "Revealing Underlying Wi-Fi Problems with Ultrafast Broadband" by Adtran, a provider of equipment for networks.

Recommended Watching: A YouTube video on how the Mexican city San Miguel Allende installed a small cell/DAS system in a historic city. La ciudad de San MIguel de Allende se pone a la vanguardia en telecomunicaciones, al contar con un sistema de antenas distribuido conectado por fibra óptica. (In Spanish with English subtitles)

Landline Phones Continue Decline

Tied to the subject above, more homes are relying on cellular phones than landlines.

Landline phone use in US

A survey by the US National Center for Health Statistics, an arm of the Centers for Disease Control and Prevention reports that in late 2017 that fewer than half the US homes have a landline anymore. That's a drop from about 85% in 2006, an average drop of 9% per year. Only a few years ago reports had landlines declining at a rate of about 6%.

"The number is remarkable for how rapidly it has increased, according to researchers behind the survey. In 2006, only 15.8% of survey respondents said they didn’t have a landline telephone. The iPhone and its Android counterparts launched the next year, and the rate of landline abandonment has since steadily climbed.

“There are countries in Europe where 80[%] to 90% of households are wireless only, so this trend could continue for some time,” said Stephen J. Blumberg, one of the researchers who compiled the NCHS report." as reported in the LA Times.

The questions this report raises are critical to the future of communications, both "phone" and Internet. If homes have no landline, is DSL - and copper to the home - effectively dead? Can wireless deliver broadband services? Or do CATV and FTTH need to provide those services? The answers to those questions seems to be a function of which industry you ask. All have solutions proposed, CATV/DOCSIS and FTTH are proven but wireless hinges of that nebulous "5G" promise.

World's Largest Internet Exchange Sues German Spy Agency For Tapping Data Center

If you have been reading the FOA Newsletter, you know we have covered the issues of tapping optical fiber several times and have a page on the FOA Guide on tapping fiber. Here is another story, now from Germany.

The operator of the world’s largest Internet hub, the German Commercial Internet Exchange (DE-CIX), has taken the German government to court over mass surveillance.

DE-CIX claims that since 2009 Germany’s foreign intelligence agency, the BND, has intercepted and copied all traffic going into its Frankfurt data center - including data on domestic citizens’ communications. German law limits mass data collection, as well as the interception of citizen data.

The Internet exchange group originally filed the lawsuit in 2016, but it has just gone to court.

The company claims the BND inserted Y-piece prisms into the fiber optic cables leading to its Frankfurt data center, duplicating all traffic and diverting copies to servers owned by the BND. It is also believed some of that data was shared with the United States’ National Security Agency.
BND supplied DE-CIX data to the NSA between 2004 and 2008.

Read more on DatacenterDynamics.

FOA Is Testing A New Training Tool - A Video Microscope

video microscope

FOA has several vendors that are "training partners" who provide tools and equipment to FOA approved schools at a discount for use in their courses. One of those vendors is EasySplicer, the maker of a low cost fusion splicer.. Another is Ripley, the manufacturer of Miller strippers. Ripley recently acquired ODM, a manufacturer of fiber optic test equipment in New Hampshire. One of the ODM tools we have been interested in for use in our schools is the ODM VIS 400 video microscope. A video microscope is perfect for classes as it can be connected to a projector so all students in a connector termination lab can see the endface of a connector at the same time and discuss the condition.

Besides being used for examining connector polish during termination, it is a way to illustrate graphically the process of inspecting/cleaning/inspecting connectors, which involves another FOA training partner, Microcare/Sticklers. When used in conjunction with ODM’s proprietary InSpec™ software the VIS 400 ensures compliance with the IEC 61300-3-35 standard.

We're evaluating the ODM VIS 400 video microscope right now and will be using it in selected FOA schools classes soon. We'll report back on how it works in Future FOA Newsletters.

Back To The Future - 10M Single Pair Ethernet

They call it IEEE 802.3cg. It's likely to be a standard by mid-2019. It's only 10 megabits/second and operates over a single twisted pair wit full duplex transmission. The question is why?

The answer appears to be a desire to retire all the older cable formats and data formats that have been standardized over the last half-century or more. That includes RS-232, RS-485, RG-6 coax, and any other proprietary networks that can be converted to operating on Ethernet. Since everything else is migrating to Ethernet, that seems to make sense. The limitation of 10M speed is understandable also since most of the networks it intends to replace are at speeds measured in kilobits/second not megabits/s or gigabits/s.

The catchall application is often stated as it's for IoT - the Internet of Things - but isn't that supposed to be all wireless? Do we sense another media battle on the lines of the copper-fiber debates of 20 years ago?

Two versions are being considered, 1km and short reach. The 1km link will cover every industrial or commercial standard system used in buildings or factories. The short reach, maybe 15m, will cover platforms like vehicles. Even use over backplanes and printed circuit boards are being considered. Of course PoE will be included.

One question we don't find an answer to is whether there will be single pair cables, four links in a current "Cat 5" type cable or will there be a return to the old Cat 3/Cat 5 multipair cables - 25 pairs or more?

Here is the explanation from IEEE 802.3.

Conference on Plastic Optical Fibers

POF 2018

The 27th International Conference on Plastic Optical Fibers (POF 2018) will be held in Seattle, Washington, USA, from September 4 to 6th.

The main theme for POF2018 is optical data networks and sensing architectures, technologies, components, materials, tools and techniques that utilize the advantages of POF.These technologies are designed to meet the harsh environment of aircraft and spacecraft applications on both commercial and military platforms. This application-oriented conference will provide an international forum for leaders, researchers, scientists, and engineers from academia and industry to share new R&D advances and discuss issues and solutions.

POF 2018 will also cover recent developments in POF technology, applications, technical standards, industry progress and new markets. Speakers from around the world will review opportunities for POF in areas such as automobile applications, Gigabit POF, 4K/8K ultra high definition television (UHDTV), home networking, active optical cables, POF sources & sensors, and high-temperature POF, among others.

For more information on POF 2018, including registration, exhibiting or submitting a paper, go to the POF 2018 website.

The following articles were first printed in the April FOA Newsletter. It's so important that we're leaving it here for another month while we integrate it into the appropriate articles in the FOA Guide.

Power Budgets, Loss Budgets, Setting A "0dB" Reference And Modal Distribution

Not only was this topic a long discussion with our new instructors but it's a common question asked of the FOA - we received two inquiries on loss budgets in the last month alone. The confusion starts with the difference between a power budget and a loss budget, so we'll start there. and we'll include the points where we were stopped to explain things.

What's The Difference Between Power Budget And Loss Budget?
Consider this diagram:
Fiber optic loss budgets
At the top is a fiber optic link with a transmitter connected to. a cable plant with a patchcord. The cable plant has 1 intermediate connection and 1 splice plus, of course, "connectors" on each end which become "connections" when the transmitter and receiver patchcords are connected. At the receiver end, a patchcord connects the cable plant to the receiver.

Question: A connector is the hardware attached to the end of a fiber which allows it ti be connected to another fiber or a transmitter or receiver. When two connectors are mated to join two fibers, usually requiring a mating adapter, it is called a connection.

Below the drawing of the fiber optic link is a graph of the power in the link over the length of the link.  The vertical scale (Y) is optical power at the distance from the transmitter shown in the horizontal (X) scale. As optical signal from the transmitter travels down the fiber, the fiber attenuation and losses in connections and splice reduces the power as shown in the green graph of the power.

Comment: That looks like an OTDR trace. Of course it does. The OTDR sends a test pulse down the fiber and backscatter allows the OTDR to convert that into a snapshot of what happens to a pulse going down the fiber. The power in the test pulse is diminished by the attenuation of the fiber and the loss in connectors and splices. In our drawing, we don't see reflectance peaks but that additional loss is included in the loss of the connector.

On the left side of the graph, we show the power coupled from the transmitter into its patchcord, measured at point #1 and the attenuated signal at the end of the patchcord connected to the receiver shown at point #2. We also show the receiver sensitivity, the minimum power required for the transmitter and receiver to send error-free data.

The difference between the transmitter output and the receiver sensitivity is the Power Budget. Expressed in dB, the power budget is the amount of loss the link can tolerate and still work properly -
to send error-free data.

The difference between the
transmitter output (point #1) and the receiver power at its input (point #2) is the actual loss of the cable plant experienced by the fiber optic data link.

Comment: That sounds like what was called "insertion loss" with a test source and power meter. Exactly! Replace "transmitter" with test source, "receiver" with power meter and "patchcords" with reference test cables and you have the diagram for insertion loss testing which we do on every cable.

The loss of the cable plant is what we estimate when we calculate a "Link Loss Budget" for the cable plant, adding up losses due to fiber attenuation, splice losses and connector losses. And sometimes we add splitters or other passive devices.

Power Budget  For A Link

Question: How is the power budget determined? Well, you test the link under operating conditions and insert loss while watching the data transmission quality. The test setup is like this:

Measuring fiber optic link power budget
Connect the transmitter and receiver with patchcords to a variable attenuator. Increase attenuation until you see the link has a high bit-error rate (BER  for digital links) or poor signal-to-noise ratio (SNR for analog links). By measuring the output of the transmitter patchcord (point #1) and the output of the receiver patchcord (point #2), you can determine the maximum loss of the link  and the maximum power the receiver can

From this test you can generate a graph that looks like this:
fiber optic BER
A receiver must have enough power to have a low BER (or high SNR, the inverse of BER) but not so much it overloads and signal distortion affects transmission. We show it as a function of receiver power here but knowing transmitter output, this curve can be translated to loss - you need low enough loss in the cable plant to have good transmission but with low loss the receiver may overload, so you add an attenuator at the receiver to get the loss up to an acceptable level.

You must realize that not all transmitters have the same power output nor do receivers have the same sensitivity, so you test several (often many) to get an idea of the variability of the devices. Depending on the point of view of the manufacturer, you generally error on the conservative side so that your likelihood of providing a customer with a pair of devices that do not work is low. It's easier that way.


Furthermore, if your link uses multimode fiber at high bit rates, there will be dispersion. Dispersion spreads out the pulses, causing a power penalty. That's why high speed Ethernet at 10G has a loss budget of 2dB while the power budget calculated from transmitter and receiver specifications is about 6dB.

Note: We've talked about measuring power. Fiber optic power meters have inputs for attaching fiber optic connectors and detectors designed to capture all the light coming out of the fiber. This connection is considered a "no loss" connection. In reality, we do not capture all the light from the fiber because there is a glass window on the detector and that window and the detector are slightly reflective. However the coupling is very consistent and when we calibrated the meter, we calibrate with a fiber optic cable under the same conditions. Thus, what we measure of the light by presenting a connector to the power meter is both consistent and calibrated (as long as you choose the proper calibration wavelength, of course.)

Fiber optic power meter detector

But what about connections from the transmitter to the patchcord and the connection of the patchcord to the receiver? We can't measure those connections because we do not have access to the actual devices the fiber is coupling to to know what the connection loss is. Therefore our measurement convention is to measure them coupled to a patchcord. We simply have to ensure we have good patchcords. A patchcord that is low loss connected to another patchcord should be low loss connected to a transmitter or receiver port.

The connection to the receiver is also unknowable. All we can do is measure the output of the cable that we connect to the receiver when testing the power budget of the link. Whatever the connection loss is becomes irrelevant, but it is included in testing of the receiver and the link.

Comment: Stan Hendryx, the MIT graduate in our class, became so interested in the notion of measuring in dB that he researched to topic and sent us a treatise on dB that includes this history:

"In 1924, engineers at Bell Telephone Laboratories adopted the logarithm to define a unit for signal loss in telephone lines, the transmission unit (TU). The TU replaced the earlier standard unit, miles of standard cable (MSC), which had been in place since the introduction of telephone cable in 1896. 1 MSC corresponded to the loss of signal power over 1 mile of standard cable. Standard cable was defined as having a resistance of 88 ohms and capacitance of 0.054 microfarads per mile. 1 MSC equals 1.056 TU. The loss factor in TU was ten times the base-10 logarithm of the ratio of the output power to the input power.
In 1928, Bell Telephone Laboratories renamed the transmission unit (TU) the decibel (dB)."
You can read Stan's paper here.

Question: If we measure the transmitter output and receiver input that way, what does that mean for calculating the loss budget or measuring insertion loss?

Once we understand the way we measure (and calibrate) power as the output of a fiber optic cable connected to a power meter, these two topics make more sense.

Refer to the first diagram of the fiber link and the power in the link. Note we measure transmitter power at point #1 on the graph, the power we use as the output of the transmitter, the reference power for insertion loss measurements or the power for the calculation of the power budget. We measure that power before the connection to the cable plant so the transmitter power is attenuated by that first connector on the cable plan. Therefore that first connector must be included in the calculation of the loss budget of the cable plant.

At the receiver end, the receiver patchcord connects to the installed cable plant and suffers connection loss before it is connected to the receiver. Thus that connection should be included in the link loss budget also.

So when calculating a link loss budget, include the connectors on both ends of the cable plant.

Note: When you do an insertion loss test, you use a meter and source and two reference cables - launch and receive. They substitute for the link cable pllant patchcords and you make measurements just like you would in testing the link power budget. Your insertion loss test will also include both connections.

One, Two, Three Cable 0dB Reference

Question: This looks like the 1-cable reference method for insertion loss testing. What happens when you use the 2-cable or 3-cable reference method? And why would you use those other methods anyway?

One common misunderstanding is why you use the two or three cable reference methods (see below) for insertion loss testing.

insertion loss test reference
Some people think it's related to how you want to perform the test, but the reason is much more a matter of practicality. It all depends on the connectors on the cable plant you are testing and the connector interfaces on your test equipment. And some history.

The 1-cable method has always been the method of choice because it does not require compensating for the connections in the reference cables when setting the "0dB" reference. It's like we discussed measuring transmitter power above. You measure the output of the launch reference cable, connect it to the cable plant under test, launch power through that first connection and measure the loss of all losses in the cable plant. The meter connects to the cable plant at the far end with a receive reference cable, and when the meter makes it's measurement it includes the connection of the receive reference cable. Thus both connections on each end of the cable plant are measured, Just like the actual link will work in operation. No corrections are needed.

But suppose you have a LC cable plant and your instruments have SC connector interfaces? Or suppose 35 years ago, you test set had SMA connectors and you needed to test a cable plant with Biconics. (Don't know those connectors? Look them up here.) You can use hybrid reference cables with SMA connections on one end for your instruments and Biconics on the other end to mate with the cable plant. Use a biconic mating adapter to set your reference - including that connection - and make measurements remembering - or ignoring - that your reference value included one unknown connection.

Or suppose you are trying to test connectors that do not match the connections on your instruments nor do they mate with each other because they are gendered - male/female or plug/jack? Hybrid reference cables won't help here, so you go to a "cable substitution" test. Set up your instruments with hybrid cables and set your reference with a third cable that is a short version of the cable plant you want to test. Since most cable plants using plug/jack connectors (like a MPO prefab cable plant or multipin military connectors) have the permanently installed cable plant end in connectors of the same gender (MPO jacks are connectors with pins), you will have your instruments with similar cables and the reference cable will have the opposite styles of connectors to mate with them.

Note: All three methods are approved in most standards and at least the 1-cable or 3-cable methods are approved in all standards we're aware of.

Note: Just remember that you will make measurements that yield different loss values depending on the reference method you use.

Question: If you use a 2-cable method don't you just reference out one of the connectors on the end of the cable plant you are testing, and if
you use a 3-cable method don't you just reference out both of the connectors on the end of the cable plant you are testing? No! Each connection is different. If you include one or two connections in your reference setting, you will reduce the loss by one or two unknown connection losses - it has nothing to do with the final insertion loss measurement which includes all connection losses from the ends of the cable plant. Here is an example by Fluke that shows the variation based on standard connection loss values.

Multimode Fiber
One thing that confuses people is how multimode fiber works. We discussed total internal reflection in fiber and how graded index multimode fiber was made in layers, so it works like this (from the FOA Guide on Fiber):


To help visualize the layers in the fiber, we like to show a Fresnel lens, a "flat" lens made from annular rings of glass that approximate a regular lens. These lenses are used in lighthouse lights like this one:

Lighthouse lens  lens

A Fresnel lens like this one used in a lighthouse is a flat lens made of segments of a regular lens.

Multimode Loss With A Mandrel Wrap, Testing The Effect In Class

When we got to the slide in the lecture about multimode mode conditioning for testing, we got into a discussion about how to do mode conditioning. One of the instructors had read about using a "mandrel wrap" on the launch cable so we spent some time discussing it. First we covered  the reason why mode power distribution makes a difference.

Here is a slide showing testing with a fully filled fiber and one where the higher order modes have been stripped off to simulate the fiber with a typical VCSEL source.

Modal effect on fiber optic connector loss

The industry has always known about the effects of modal distribution and has created metrics to measure and standardize it for testing multimode fiber. The methods included MPD (mode power distribution), CPR (coupled power ratio) and the latest, EF (Encircled Flux.) 

In class, the instructors had each made at least one good connector in our termination lab (we were using the most basic technique, heat-cured epoxy and polishing) so we decided to test their connectors with and without a mandrel wrap mode conditioner to see if it made a difference.

mandrel wrap

After adding the mandrel wrap to the launch cable, we tested the LED test source using a HOML (higher order mode loss) test as described in the page on EFWith the mandrel wrap, the power was reduced by ~0.6dB, so we left the mandrel on for our testing.

Adding the mandrel wrap certainly did make a difference. Connectors tested single-ended without the mandrel wrap at ~0.6dB loss were measured at ~0.2dB with the mandrel wrap. That's how much difference modal conditioning can make on a single connector.

Think about that the next time you are testing multimode fiber!

That's all our notes from this instructor training session. Hope you found them interesting!

Notes from the field...An Interesting Puzzle This Month

OTDR Bi-Directional Confusion

OTDR 2-way-problem

The prime contractor of the network was confused. About half the fibers in a cable showed traces that looked like this - hardly any loss in one direction and ~1.4dB loss in the other direction. The engineer who called us was familiar with fiber but had never seen anything like this. Neither had we.

Was it possible that the two cables spliced at this point had different fibers? G.652 and G.655 might cause a high loss in one direction, but 1) that would mean average splice losses of ~0.7dB, hard to get with a modern fusion splicer, 2) the cables were from the same suppliers and 3) the problem was with only half the fibers.

We passed this one around to our OTDR experts around the world. One even called the engineer to discuss it at length.

Finally, the installer identified the problem. After splicing all the fibers and testing in one direction, the installer dropped the splice closure while installing it on a pole. Rather than testing again to confirm it was OK, they finished installing the closure and tested from the opposite direction a few days later, finding that about half the fibers had been damaged.

There are a few lessons here. 1) Be careful when installing components to not damage them. 2) If you think you did damage something, test immediately to assess the damage. 3) Look at your data before you submit a report to ensure it is logical, especially OTDR data.

How "Fast" Is Fiber?

One of the FOA instructors sent us this question:  "I work with at Washington Univ with an engineer who works for an electrical utility. He asked a question about the speed of signal transmission over fiber optics, single mode, at top of towers. They need signal to be sent in 18 millisecs for relays to function properly. Is there a problem over a distance of 150 miles?"

Electrical transmission lines

Let’s do a calculation:

C = speed of light in a vacuum = 300,000 km/s = 186,000 miles/sec
V= speed of light in a fiber = c/index of refraction of fiber (~1.46) = 205,000 km/s or 127,000 miles/sec
150 miles / 127,000 miles/sec = 0.00118 seconds or ~1.2 milliseconds

Another way to look at it is 127,000 miles/sec X 0.018 seconds (18ms) = 2,286 miles

So the fiber transit time is not an issue. The electronics conversion times might be larger than that.

I used to explain to classes that light travels about this fast:

300,000 km / sec
300 km / millisecond
0.3km /microsecond or 300m / microsecond
0.3 m per nanosecond - so in a billionth of a second, light travels about 30cm or 12 inches

Since it travels slower by the ration of the index of refraction, 1.46, that becomes about 20cm or 8 inches per nanosecond.

That is useful to know since an OTDR pulse 10ns wide translates to about 200cm or 2 m pr 80 inches (6 feet and 8 inches), giving you an idea of the pulse width in distance in the fiber or an idea of the best resolution of the OTDR with that pulse width. 

Why You Clean Connectors Before You Make Connections

Brian Teague of Microcare/Sticklers send us this series of photos showing what happens when you make connections with dirty connectors. It speak for itself!

Dirt on fiber optic connectors

Recycling Fiber Optic Cable

We received this note from Steve Maginnis, LD4Recycle/ CommuniCom Recycling on recycling fiber optic cable:

We have 3 Processors gearing up to accept fiber optic cable (FOC). As we all know, all FOC is not the same. Several truckloads of “typical” FOC scrap from FOC mfgrs and “typical” FOC and Coax cable have been studied and tested.

Therefore, today you can begin contacting me with the type FOC material or scrap you toss to the landfills today. We need to quantify the expected feedstock. Our expectation for quantities is quite large (tons) but there is a capacity limit. And I do have several processors that can take ALL materials and others that can accept LIMITED types of FOC material and quantity.

Steve Maginnis
LD4Recycle/ CommuniCom Recycling
(Visit our new website)

What Does A FTTH ONT Look Like Today?


That's all there is to the ONT that goes into the home. The arrow points to the 1310 TX/1490 RX transceiver for SC-APC connectors.

Color Codes Added For 16-Fiber MPO Connectors

There is a new standard for MPO connectors with 16 fiber rows. Now we need color codes for fibers 13-16 and they have been selected, as shown in this table.

Color codes 16 fibers

If you are familiar with the MPO standards, there are dozens of pages of diagrams for polarity on the 12 fiber MPO. Wonder how many there will be for this one?

Best Practices Guide For Underground Construction

Best Practices - CGA

We assume you are familiar with the "One Call" and "Call Before You Dig" (811) program, but are you also familiar with the people behind it - the Common Ground Alliance and their Best Practices website?

CGA is a member-driven association of 1,700 individuals, organizations and sponsors in every facet of the underground utility industry. Established in 2000, CGA is committed to saving lives and preventing damage to underground infrastructure by promoting effective damage prevention practices. CGA has established itself as the leading organization in an effort to reduce damages to underground facilities in North America through shared responsibility among all stakeholders.

Officially formed in 2000, the CGA represents a continuation of the damage prevention efforts embodied by the Common Ground Study. Sponsored by the U.S. Department of Transportation and completed in 1999, this Study represents the collaborative work of 160 industry professionals who identified best practices relating to damage prevention.
Any best practice or program endorsed by the CGA comes with consensus support from experts representing the following stakeholder groups: Excavators, Locators, Road Builders, Electric, Telecommunications, Oil, Gas Distribution, Gas Transmission, Railroad, One Call, Public Works, Equipment Manufacturing, State Regulators, Insurance, Emergency Services and Engineering/Design.

Read the CGA Best Practices Guide here.

Here are all the CGA resources for damage prevention.

Welcome New FOA Corporate Members

The following companies are new corporate members this month. You can find more information on these and hundreds of other FOA Corporate Members in our FOA Corporate database in map and list form.There you will find many companies involved in fiber optics that can help you with products and services to fill your needs.

Consult-comm, Sanford FL
Combotech, Athens, Greece
Poirier Telecom, Ballinafad Ontario, CA
Profy Technologies, Sandton South Africa

Should Your Company Become An FOA Corporate Member?

Keeping Up To Date With Fiber Optics And Premises Cabling

We just finished updating two of the books and a third is in the works. Along with the changes we make to the books, we update the FOA Guide with the same materials. Here is a rundown of the updates we have just completed of The FOA Reference Guide To Fiber Optics and The FOA Reference Guide To Premises Cabling. We should have the last updates - The FOA Reference Guide To Outside Plant Fiber Optics - completed by next month.

FOA Reference Guide to Fiber Optics book  FOA Reference Guide to Premises Cablng book  FOA Reference Guide to OSP Fiber Optics book
The FOA Reference Guide To Fiber Optics has been updated to cover some new technology like bend-insensitive fiber, OM5 fiber, SOCs (fusion splice-on connectors), microcables and microducts. We added information on datalinks on a single fiber like PONs, DWDM and CWDM. We expanded the chapter on testing to include much more information on
visual inspection and connector cleaning, OTDRs and Fiber Characterization. The same updates have been made to the online material in Fiber Optics - The Basics in the FOA Guide online

Premises cabling has not been standing still either. We did many updates to the
The FOA Reference Guide To Premises Cabling this time. We updated the cable types to include Cat 8, added a section on PoE (power over Ethernet), explained the nomenclature used in the latest TIA 568 standards, added information on POLs (passive optical LANs), DAS (distributed antenna systems for cellular) and a complete new Appendix on Data Centers. In the fiber optic chapter, we expanded the material on fiber to include POLs, visual inspection and connector cleaning and OTDR testing. The same updates have been made to the online material in Premises Cabling in the FOA Guide online. We also added a new page just on PoE (Power over Ethernet)  to explain its background, applications and potential issues.

We have also updated the FOA Reference Guide To Outside Plant FIber Optics. It
has been updated to cover some new technology like bend-insensitive fiber, OM5 fiber, SOCs (fusion splice-on connectors), microcables and microducts. We added information on datalinks on a single fiber like PONs, DWDM and CWDM. We expanded the chapter on testing to include much more information on visual inspection and connector cleaning, OTDRs and Fiber Characterization.
So if you look up information on the
FOA Guide online or purchase a FOA printed textbook you will now have the latest information. Since we've been updating our reference materials used for training, the related courses on Fiber U are updated also. Finally, we're updating our curriculum used by FOA approved schools to ensure their students get the latest information.

This is just another way that FOA tries to make the most up-to-date, technically correct information available to everyone in the industry.

A Short (Pictorial) History Of Modern Telecommunications

FOA has been asked a lot of questions about how modern telecommunications developed. We've been adding information about the history to some of our seminars and recently to our curriculum presentations. The FOA history follows the development of modern communications through Bell, Marconi, De Forest, Shannon, Kao and the personnel at Corning and Bell Labs who have made modern communications possible.

Morse  Morse and his telegraph

We think you will find A Short History of Modern Telecommunications interesting. Next we'll add articles on LANs and structured cabling and the development of fiber optics.

Trivia for photographers: this photo of Morse was taken not long after photography began in America - the early 1840s. The original is now on display in the Getty Center in LA as part of an exhibition of early American photography.

A Conversation About Fiber And Testing

Recently an extended conversation between Eric Pearson and Jim Hayes, both FOA founders, covered the issues of testing fibers at multiple wavelengths. We've summarized the conversation here because there is some very interesting and useful information in it.

March 2018 update: Here is a OTDR trace from EXFO Eric uses in one of his books to illustrate bend sensitivity of fiber and different wavelengths:

OTDR bend sensitivity

And our conversation from February 2018:

EP: Testing multimode fiber at both wavelengths (850 and 1300nm) has been recommended to evaluate the presence of stress. If EF (encircled flux) testing fills the 30µ center of the core and 1300 nm testing fills the entire core, is it possible that this difference in core fill would indicate stress, even though there is no stress?

JH: There are definitions for EF testing at 1300nm for multimode with similar mode fill requirements included in various standards documents that cover EF so there should be no difference in stress loss due to mode fill. However, you need a 1300nm EF source.  But using 1300 nm for finding stress loss may be irrelevant since the majority of multimode fiber today is bend-insensitive (BI) fiber. That's becoming true for more singlemode fiber also, as BI SM fiber is used in microcables, spider ribbons and other new cable types.

EP: Is there any reason to test multimode at both 850 and 1300 nm then? How about SM at both 1310 and 1550?

JH: The issue of dropping 1300nm testing of MM fiber has been discussed in standards committees for years. Since the advent of the cheap VCSEL - which of course is only feasible at 850nm - there is practically no use of MM fiber at 1300nm and no real reason to test at that wavelength. But just try to remove something from a standard - it's just about impossible!

The issue of SM fiber at 1310 and 1550nm is different. Today most SM fiber is probably used at both 1310 and around 1550nm with DWDM systems and PONs, so testing at both wavelengths is necessary. Much of the testing of SM fiber for stress is done by OTDRs at 1625nm anyway, but I do not know how that is affected by BI fiber structures.

The whole topic of testing MM fiber skirts the BI fiber issues. Controlling mode distribution in BI fiber is problematic. Those 20-25mm mandrels you used for regular MMF don't work with BI fiber. It takes a mandrel ~6mm to produce the same mode filtering as a 20-25mm mandrel, but then the BI fiber structure simply refills the higher order modes. Creating EF in BI fiber is questionable. Standards have recommended against using BI fibers for reference cables (because it produces higher losses than mode-filtered regular fiber) but you are probably testing cable plants with BI fibers. Finding non-BI fiber patchcords to use for reference cables is difficult since most MM fiber is BI. Some manufacturers have made nothing but BI fiber for nearly a decade!

Historical Footnote 1: As an example of how long this issue has been discussed, look at these two clips from Corning AEN-131 from 2009.

fiber testing

fiber testing

Historical Footnote 2: While searching for this ap note (we found it in our own files where we had downloaded it in 2010), we found another interesting Corning ap note, AN3060, March 2014, on OTDR testing of SM fiber fusion splices.

What interested us was this graph, showing OTDR loss measurement differences depending on direction and mode field diameter differences.

OTDR errors with MFD

We remembered another graph similar to this that we (JH) created 30 years ago. You can tell its age by the crudeness of the computer generated graph from Lotus 123, an early spreadsheet program.

OTDR errors with MFD

This data was taken with some early singlemode fibers and an early OTDR from a sample of Spectran SM fiber spliced to Corning fibers. The work was done for Spectran to show their fibers could be spliced to Corning fibers. We obtained the data from a contact at Spectran specifically to analyze for directional loss differences and show why "gainers" happened. This graph was one of two graphs that showed the reason - gainers were caused by backscatter differences in fiber of differing mode field diameters (MFD.)

Out of curiosity we overlaid a red line showing the modern Corning data and the similarity is obvious. The scattering is much less because fibers today are much more consistent (Corning's largest MFD difference was 0.3 microns and the 1980s fiber MFD varied up to 0.8 microns, a combination of actual fiber variations and the greater errors in measurements then) and modern OTDR data is undoubtedly more consistent too.

In our analysis of the data, we also had data on the attenuation coefficient of the fiber, so we looked at another relationship that we thought would be useful - loss difference vs the difference in fiber attenuation coefficient.

OTDR errors

Within the limitations of the data, it's obvious that the directional difference in splice loss is also related to the difference in the attenuation coefficient of the fiber. We found this very interesting because most techs running OTDR tests do not have data on MFD but they can easily measure the attenuation coefficient of the two fibers being spliced. With these early fibers, a difference in fiber attenuation of 0.1dB/km would indicate a loss difference of around 0.4dB. Looking at the difference in fiber attenuation could provide an indication of the potential error of the OTDR loss measurement.

OTDRs could easily calculate this - the data is imbedded in the LSA splice loss measurement. Perhaps if someone would repeat the Corning test with modern fibers and duplicate the graph above to show the relationship of
difference in the attenuation coefficient to the difference in splice loss and it looked better - like the Corning data on modern fibers - the OTDR manufacturers might incorporate this and provide a better single-ended splice loss test.

Nitpicking: The Corning graph has a series of black dots labeled "Actual Splice Loss." In the paper they refer to them as "
bi-directional averaged (actual) splice loss values." While that is a commonly accepted fact, technically it's inaccurate. It is really an average splice loss for the two directions, because if you measure the actual loss of a splice between two fibers in each direction, you will find the difference in MFD will cause real differences in loss in each direction. Measuring it is non-trivial, however, and the difference is small with small MFD differences. We go into this in the new FOA book on testing.

FOA Book on Fiber Optic TestingFOA Reference Guide To Fiber Optic Testing


We've spent some time on this topic ourselves, noting that downstream testing is confusing and upstream testing is the only solution. But FOA Master Instructor Joe Botha of Triple Play Fibre Optics  in South Africa has encountered a new issue - drop cables are often BI fibre (G.657A) while feeder and distribution cables are regular G.652D. He's done some research on the issues and written an article for a website in South Africa we can share with you.
Read more.

PoE And Counterfeit Cable

PoE Efficiency Superior Essex Comparison Of Cable Efficiency

This graph showed up in an interesting white paper on PoE from Superior Essex, LeGrand and Fluke. You might remember we did an analysis of PoE power efficiency in the November FOA Newsletter article "PoE Analysis From The Ethernet Alliance (With Our Analysis). This graph has some data we did not consider - the efficiency of counterfeit cable that uses copper-clad aluminum conductors instead of pure copper. The inefficiency of this cable means that more than half the power will be lost in transmission - not only inefficient but dangerous as the power lost is converted to heat. Considering that the samples of counterfeit cable that we have tested use flammable insulation and jackets, that could be a very hazardous application!

Recent conversations with people involved with adding PoE applications to the US National Electric Code bring up a further problem. The IEEE did not register "PoE" as a trademark so it's being used to describe applications like daisy-chained lighting and cables longer than the 100m limit of Ethernet. This makes the safety considerations even more important - and scary.

FOA is researching PoE as part of our CPCT certification and have created a FOA Guide page on PoE which we will be updating regularly.

Find us on Facebook Comments
Robert Michael Murphy
 I just completed the CFOT Certification course at EIA in Akron, PA with Arnie Harris and I have to say that his training and your books are some of the best I have seen. The Book was easy to read and to understand, Arnie explained everything at a level we could understand and then expanded on the information as we learned more and more. It was some long days and it was worth it! Thank you and Thank you, Arnie Harris, for the great teaching! It is much appreciated! I will be back again to take more of your courses!

EIA - FOA School #195.

FOA Facts

FOA is a non-profit professional society whose members are all certified techs - mostly CFOT®s -Certified Fiber Optic Technicians - but also may be CPCTs - Certified Premises Cabling Technicians or corporate members involved in fiber optics.

FOA is a "virtual organization" - we have no "brick and mortar" presence. We operate over the Internet with operations centered in California, with active workers and volunteers in locations as diverse as Texas, Ohio, Canada, Singapore, Malaysia, Denmark, South Africa, the Middle East and many more.

Being a virtual organization, FOA has very low overhead, allowing us to offer cost-effective certifications and many free programs to support our industry.

CFOT Total
As of today, FOA has certified this many techs. About 90% come from our schools but many experienced techs have become FOA CFOT-certified directly through our "Work-to-Cert" program.

FOA has almost 200 approved training organizations in about 40 countries around the world around the world.


FOA has 14 fiber optic certification programs covering every aspect of fiber optic network design, installation and operation.

Primary Certifications: CFOT (basic fiber), CPCT (premises cabling), CFOS/O (outside plant, taught with CFOT included) and CFOS/D (fiber optic network design).

Skills Certifications (for installers and techs, requires CFOT): CFOS/S (splicing), CFOS/C (connectors/termination), CFOS/T (testing), CFOS/FC (fiber characterization).

Applications Certifications (for techs or anyone, including managers and supervisors): FTTH (fiber to the home), CFOS/L (optical LANs), CFOS/DC (data centers), CFOS/A (fiber to the antenna), CFOS/DAS (distributed antenna systems) and CFOS/W (fiber for wireless)

FOA monitors the trade press, websites and other resources continually to look at what's happening in many technologies that affect fiber optics. We're tracing technologies as diverse as wireless, IoT, autonomous vehicles, smart cities, energy, or anywhere fiber is used to bring news to our readers.

FOA continually updates our technical materials, online and printed, and our curriculum to ensure our readers have access to the latest technical information and our schools teach the latest technology and applications. Our printed books are being updated right now.

FOA Guide
FOA created the FOA Online Guide as a non-commercial trustworthy technical reference almost a decade ago so the industry would have a reliable technical reference. In the last year, over 1million visitors downloaded about 4 million pages of technical information.

FOA offers free online self-study programs at Fiber U. In 2017, the number of online sessions doubled to 200,000. Many of those are preparing for FOA certification programs - taking courses at our schools or using the "Work-to-Cert" program. Some of our schools are requiring Fiber U programs as prerequisites for their classroom courses so they can spend more time on hands-on activities.


FOA offers over 100 educational YouTube videos that have been viewed 2.4 million times.

FOA offers its training programs to other organizations at no cost to help them train their members properly in fiber optics. For example, FOA has been working with the Electrical Training Alliance (IBEW/NECA) for over 20 years, training their instructors for their apprenticeship programs. We work with many other organizations and companies to provide the materials they need.

FOA has about 300 corporate members - companies in various aspects of the fiber optic industry worldwide that we list online and offer discounts on certifications and renewals.

FOA provides speakers for many conferences and even presentations for use by other organizations to educate people on the aspects of fiber optic communications.

FOA has a program to provide
classroom materials for STEM teachers (science, technology, engineering and math) introducing K-12 students to fiber optics and creating science projects.

FOA provides forums for discussion on various social media. Our LinkedIn groups have about 5,000 members each. If you are not joining us on social media yet, please do.

Find us on Facebook  FOA on LinkedIn  videos 
Pinterest  Twitter

New From FOA

New FOA YouTube Video

Smart Cities Are Built On Fiber

Everyone's talking about "Smart Cities" but what makes a city smart? It's a combination of services that will be delivered over an extensive fiber optic network. This video examines an advanced Smart City, Santa Monica, California, and looks the current services that make it a smart city today and what possible services can be delivered in a Smart City over fiber in the future.

Smart Cities Are Built On Fiber on YouTube

New FOA "Fiber For Wireless" Curriculum And Certification

Fiber For Wireless

Fiber has become the critical part of the infrastructure for the expansion of wireless communications. Just a few years ago, fiber was used to connect cell sites to the telecom system and backbones for enterprise LANs that were adding WiFi wireless access points. Now mobile devices and demand for bandwidth are driving major changes to these applications.

Today, we have LTE and 5G coming, RAN and Gigabit WiFi. We need fiber backhaul to the traditional cell sites and up the tower to the antennas, new architectures like fiber fronthaul or C-RAN that support the traditional cell sites plus small cells and DAS - distributed antenna systems inside buildings and campuses. We have enterprise WiFi, metro WiFi and even rural WiFi being used for broadband Internet. All depend on a fiber infrastructure to deliver sufficient bandwidth to meet user demands.

FOA has created a “Fiber For Wireless” program to cover all these applications (and define all the TLS - three letter acronyms - so loved by tech industries!) We talked to managers and technicians at telcos who are looking at all types of wireless options, contractors who focus on wireless infrastructure of all types, metro and utility personnel who use all types of communications and of course manufacturers of these new products.

Who’s the audience? People who just want to know about the intersection of these two modern, fast changing technologies.

The FOA “Fiber For Wireless” application specialist curriculum and CFOS/W certification will give you the background you need to understand the dynamics of today’s mobile applications and prepare you to participate in those technologies. Look for it to be available from select FOA schools and online at Fiber U in the very near future.

Have You Downloaded Your Copy Of The Updated ANSI/NECA/FOA Fiber Optic Installation Standard Yet?

Available Free Courtesy of FOA

NECA 301

NECA/FOA-301was created to be a document that could be used as a guide to installation practices and also be quoted in project paperwork to define what was meant by installation in a "neat and workmanlike manner." This standard was the first standard to approach the issues of installation of fiber optics in a document that could be used by network owners, project managers, contractors, installers, test techs, maintenance personnel and even the manufacturers making the products being installed following this standard.
Go here for more information on NECA/FOA-301 and directions for a free download.

FOA's Latest Textbook - Fiber Optic Testing

FOA Book on Fiber Optic Testing

FOA Reference Guide To Fiber Optic Testing

Libro de Diseño para Redes de Fibra Óptica en Español - FOA Design Book Available In Spanish - Online

Design in Spanish

La Asociación Profesional de Fibra Óptica (The FOA) ha traducido y hecho disponible en Español, la “Guía de Diseño para Fibra Óptica”. Esto para todos los interesados en estudiar para la certificación CFOS/D en su idioma nativo. Puede acceder a la traducción al libro de Diseño en línea utilizando este enlace. La versión impresa del libro estará disponible muy prontamente.

FOA has translated the FOA Guide To Fiber Optic Network Design book and made it available online to those studying for the CFOS/D Certification but whose native language is Spanish. You can access the Spanish translation of the Design book here. A printed version will be available in the near future.

FOA YouTube Videos Now "Closed Captioned"

FOA's YouTube videos are very popular as you can see from the statistics above. We have had requests from teachers and viewers for closed-captioning. Now FOA is upgrading all its YouTube Videos to offer "closed captioning" for those with hearing disabilities - or if you want to view the video quietly and don't have headphones. FOA used a highly-regarded service that does closed-captioning for many of the television networks to ensure accurate captioning.

FOA YouTube  Video Closed Captioning

The closed captioning can be turned on by the small "CC" button on the lower right side of the video (right arrow). The captioning shows up on screen in white letters on a black background (left arrow). You can view this video on fiber optic testing here, and try the "CC" button to see how it works.

We hope our viewers find this helpful.

FOA has over 100 YouTube videos on fiber optics, premises cabling and the fiber optic job marketplace. Here is a list with links to them online.

New Website Keeps You Up To Date On Structured Cabling

Liz Goldsmith, manager of the TIA Fiber Optic Technology Consortium (FOTC) has started a new website that aims to keep readers up to data on the news and products in the structured cabling (premises cabling) space. Called Structured Cabling News, it offers news about the industry in more than a dozen categories so you can browse the news by categories (like fiber) that interest you most. Liz sums up the aim of SCN as "SCN brings you current Structured Cabling News curated by category and topic. We search the 'Net so you don't have to - updated daily with industry trends, new products and best practice from industry leaders."

And you can subscribe to daily or weekly digests to keep yourself informed.

Structured Cabling News

Interested In A Career In Fiber Optics?

Careers in fiber optics

FOA has created a new YouTube video to introduce students to careers in fiber optics. It was made for showing to high school and junior high students interested in tech careers but anyone interested in a possible career in this field will find it interesting. If you have kids in school or know teachers, let them know about this too. Watch the FOA Careers In Fiber Optics Video on YouTube and visit the
FOA Careers In Fiber Optics web page at

New Viavi Database Illustrates More Than 500 Operational or Planned Deployments Of Gigabit Broadband Globally

Gigabit monitor

Communications service providers worldwide are accelerating efforts to deliver gigabit internet -- network speed that is 159 times faster than the global average of 6.3 Mbps. The Gigabit Monitor, a visual database referencing current and planned gigabit deployments around the world, from Viavi Solutions (the test equipement company formerly known as JDSU). The Gigabit Monitor paints a picture of mobile, cable and telecom service providers all racing to deliver lightning-fast internet connectivity to meet end users' demands. The database, developed completely from public information, is available at:

Below are some of the key insights from the Gigabit Monitor:
  • State of gigabit: There are now at least 350 live gigabit deployments globally, with a further 164 announced or under construction, across wireline and wireless technologies including GPON, DOCSIS 3.1,, LTE-A, 5G and 802.11ac.
  • Contrasts by region: North America has the largest share of announced gigabit deployments, with 61 percent. Europe is second with 24 percent. Asia, Australasia, Middle East, Africa and South America share the remaining 15 percent of deployments.
  • Deployments accelerate: The pace of gigabit deployments has accelerated sharply. Over 70 percent of the live gigabit deployments tracked have been launched since the start of 2015.
  • Fiber dominates: 85 percent of currently known gigabit deployments are based on optical fiber connectivity. 11 percent are based on Hybrid-fiber coax (HFC), a broadband technology that combines optical fiber and coaxial cable, commonly employed by cable providers.
  • Wireless gigabit is already here: Nearly 3 percent of known gigabit deployments are based on LTE-A, a modified version of LTE which is gigabit-capable.
  • 5G is coming fast: 37 wireless carriers have announced plans for 5G networks. Five of them plan to have 5G networks built as early as 2017.

Dig Once

The word on the "Dig Once" program is getting out - FOA is getting calls from cities asking us for information and advice. It helps that the current Administration is trying to convince cities of the advantages of installing ducts or conduits when they dig up a street so they don't have to do it again. Here are some links for more information.

The DoT page on the administration’s Executive Order:
From the Council of State governments:
From the city of San Francisco:
An article about Dakota County, MN:

And the one to download and hand out:
A “How To” Guide from The Global Connect Initiative:

Useful Online Resources

We often have contacts give us online links for useful information which we like to share with our readers. Here are two:

Want To Learn More About DIY FTTH?

SW Southern Fiberworx is a DIY FTTH Project in Georgia

It seems like every week FOA gets another call from a town, real estate developer or utility wanting to start a FTTH project for their area. FOA has created several videos and a a web page on this topic to help anyone get started.

FTTH Case Studies: Do-It-Yourself FTTH

FOA has a series of videos on do it yourself (DIY) FTTH. The first three videos are online now:

FOA Lecture 45 Do It Yourself FTTH (Fiber to the Home)  What's involved in building a FTTH network of your own.

FOA Lecture 46 Do It Yourself FTTH (Southern Fiberworx)   (FOA Newsletter November 2015) How one company, Southern Fiberworx in Cordele, GA did it themselves.

FOA Lecture 46 Do It Yourself FTTH (Southern Fiberworx)   (FOA Newsletter November 2015)

Why We Warn You To Be Careful About Fiber Shards

Fiber in Finger

Photo courtesy  Brian Brandstetter,  Mississauga Training Consultants

Another Source Of Articles On Fiber

FOA President and editor of this newsletter Jim Hayes has also been writing a column in Electrical Contractor Magazine for more than 15 years now. Electrical contractors do lots of fiber work and this column has covered some toics they are interested in including installation processes, network design, fiber applications and in the last year, a lengthy series on dark fiber - what it is, how's its used and how it benefits the growth of communication. A recent web site redesign makes it easier to browse all these articles - just go to and you can see all of them.

Fiber Optic Education For Students At Any Age 

We hear about fiber optics all the time - it's in the news whenever we hear articles about high tech, the Internet and communications, and many communities are getting "fiber to the home." But few people really understand fiber optics or how it works. FOA is focused on educating the workforce that installs and operates these fiber optic networks but we're always getting inquiries from STEM (science, technology, engineering and math) teachers who want to introduce fiber optics to younger students in K-12 grades or technical schools.

We start with the FOA Careers In Fiber Optics Video on YouTube and visit the FOA Careers In Fiber Optics web page at These are for students who think they might be interested in careers in fiber optics and want to know more about what fiber techs do.

Teachers for fiber optics
Using red laser light (a VFL here but a laser pointer works also) to show how fiber guides light.

FOA has begun developing a series of YouTube videos intended for teaching students in elementary, middle and high schools about fiber optics. The first FOA video is titled "Fiber Optics For Teachers." With this video, we show teachers how fiber works and carries signals and then explains simple experiments to demonstrate how fiber optics works in the classroom using some plastic fiber and a laser pointer. Since many teachers do not know where to get the fiber, the FOA offers to send them a sample for use in demonstrations in their classroom (USA only right now.)

At the end of the video, teachers are given directions on how to request samples of the plastic fiber from the FOA.

This video joins the "Fiber Optics Live" series How Light Travels In A FiberFiber Attenuation and Connector Loss that show how fiber works using simple experiments that can be duplicated in any classroom. More videos will be coming soon.

If you have kids or know some teachers who would be interested, please send them to the introductory video Fiber Optics For Teachers  and we'll be glad to help them get started with some entertaining programs for their classrooms.

Resources For Teachers In K-12 And Technical Schools

Teachers in all grades can introduce their students to fiber optic technology with some simple demonstrations. FOA has created a page for STEM or STEAM (science, technology, engineering, arts and math) teachers with materials appropriate to their classes. Fiber Optic Resources For Teachers.


If you have kids in school or know teachers who are interested, send them to the FOA page Fiber Optic Resources For Teachers.

Should Your Company Become An FOA Corporate Member?

As all FOA individual members know, they join the FOA by becoming certified, mostly taking their CFOTs but some CPCTs,  either by attending a FOA approved school or joining directly based on field experience (our "work to cert" program.) Over the years, we've been contacted by manufacturers, contractors, consultants, and other types of organizations who ask about becoming members.

We don't certify companies or organizations, we told them, so we were not sure what we could offer as a benefit of membership. But then, companies asked about using our educational programs to train employees, how they could get listed on the FOA website as service providers or if they could get a quantity discount on membership or certification for all the FOA members working for them. That began to sound like a benefit for being an FOA corporate member. And providing a list of useful suppliers to the market could be a benefit to the industry as a whole.

So FOA has quietly been letting companies and other organizations join the FOA to take advantage of those benefits so we now have several hundred corporate members. We've put then into a database and listed them on the FOA website in map and list form. Here's the map.

FOA Corporate members

The online
map and list can be used to find suppliers and service providers.

The map, like our map of schools, lets you find the FOA corporate members close to you.  The table form lists them by category: Installer/Contractor, Component Manufacturer, Installation Equip. Manufacturer, Transmission Equipment, Services/Consulting, Distribution and Users of Fiber Optic Networks. You can sort the tables to find members meeting your needs, e.g. by location, certifications offered, etc. Click on any column heading to sort that column; click twice to sort in reverse order.

How Does An Organization Become An FOA Corporate Member?

Simple, just fill in the online application form. When your application is accepted, you will be asked to pay the membership fee -  $100US first year, $50US/year or $100US/3years to renew. You will then be listed on the online  map and list, have access to exclusive FOA educational materials for your employees and get discounts on certifications and renewals. 

Safety On The Job

bucket truck job  Pipeline explosion

Safety is the most important part of any job. Installers need to understand the safety issues to be safe. An excellent guide to analyzing job hazards is from OSHA, the US Occupational Safety and Health Administration. Here is a link to their guide for job hazard analysis.

FOA also has lots of information on safety: FOA Guide, YouTube video and a Safety Poster

"Worth Reading" Is Now OnPin

Join FOA on Pinterest. We have been posting links to pages "Worth Reading" on a special FOA Pinterest page. You can join and keep up to date with the news on our industry which we put there.

Recent posts cover utilities using new generation telecom, India's plan for 100 smart cities, Cincinnati Bell bets on fiber, various opinions on the US battle over net neutrality, etc.


Good Practice Tools For OTDRs, All Free

FOA OTDR Simulator
You may already know that the FOA has a free OTDR Simulator you can download from our website (go here for directions) that allows you to practice using an OTDR on your PC (Win XP or 7), seeing the effects of changing setup parameters and analyzing dozens of real world traces. But here are two more tools that can be good for practice.

Including more hints from FOA Master Instructor Terry O'Malley like tests on what the end of a fiber trace looks like with broken and cleaved fibers.
Frequently Asked Questions On OTDRS And Hints On Their Use  

"Fiberizer" APP Reads, Analyzes OTDR Traces
Fiberizer is a iPhone/iPad APP that reads industry-standard ".sor" format files and allows trace analysis on your iPhone or iPad. An android version is in the works too. Read more about Fiberizer. And here are more directions on its use.


Events of Interest

FOA now posts events on our LinkedIn groups, Facebook page and other social media

FOA on LinkedIn

FOA has a company page and three LinkedIn Groups

FOA - official company page on LinkedIn
FOA - covers FOA, technology and jobs in the fiber optic marketplace

FOA Fiber Optic Training - open to all, covers fiber optic technology and training topics

Grupo de La Asociación de Fibra Óptica FOA (Español)  


FOA LogoWhat's Happening @ FOA

FOA Standards:

FOA now offers free standards for datalinks and testing the installed fiber optic cable plant, patchcords and cable, optical power from transmitters or at receivers and OTDR testing.
Look for the "1 PageStandard" web page and in the FOA Online Reference Guide.

View the  FOA YouTube Video On FOA Standards 

NECA/FOA 301 Fiber Optic Installation Standard

NECA 301
Standards cover components and systems and how to test them, but rarely get into installation issues. The FOA NECA 301 standard which covers installation of optical fiber systems has been revised for the second time, adding considerable new materials. This standard is derived from FOA educational material put in standards form and approved by ANSI as an American National Standard. It's specifically written to be used in contracts to define "installation in a neat and workmanlike manner." The standard is available from NECA.   FOA members can go here for instructions on how to download your free copy.


Fiber U

Free Fiber U Self-Study Programs

FOA's "Fiber U" free online self-study programs help you learn about fiber optics, study for FOA certifications or use them to help create "blended learning" classes. There are two new free online self-study programs on Fiber U. Fiber Optic Network Design is for those interested in learning more about how to design fiber optic networks or studying for the CFOS/D certification. FTTx is for those wanting to know more about fiber to the "x" - curb, home, wireless, etc. - or studying for the CFOS/H certification.
Got to Fiber U for more information.

Fiber U Online Self-Study Programs Offer Certificates of Completion

FOA has been offering quite a few free online self-study programs on Fiber U, our online learning site. We are always getting questions about getting a certificate for completing the course online, so we have setup an option to take a test online and get a certificate of completion for these online courses.

Fiber U certificate

While it's not FOA certification, FOA will recognize a
Fiber U Certificate of Completion as background experience to qualify for applying for FOA certifications. We also intend to expand the program to more specialized topics as preparation for FOA specialist certifications.

If you have associates that want to get started in fiber, have them take this course online to get started. Go to  Fiber U and get started.

FOA Books And Publications

New FOA Reference Guide To Fiber Optic Testing

FOA Book on Fiber Optic Testing

FOA Basic Fiber Optic Textbook Now Also Available in French and Spanish

FOA Text in French FOA text in Spanish FOA Reference Guide to Fiber Optics book    FOA Reference Guide to Premises Cablng book    FOA Reference Guide to OSP Fiber Optics book

FOA Reference Guide To Fiber Optic Network Design And FOA's Outside Plant Fiber Optic Construction Guide

FOA Guide To Fiber Optic Network Design  FOA Outside Plant Fiber Optics Construction Guide

Read More about the FOA Reference Guide To Fiber Optic Network Design  and More information on the FOA Outside Plant Fiber Optics Construction Guide

Lennie & Uncle Ted Guides - Perfect For Getting Started

Lennie and Uncle Ted's Guides have moved  to the FOA website. Lennie is the place where many if not most fiber techs begin their education. FOA has just updated the two guides to ensure they stay relevant - more than 20 years after they were first written.

Lennie goes all the way back to 1993 when he was created as the mascot of the original "Fiber U" conference - the same Fiber U that is now the FOA's web-based training site. Lennie Lightwave's Guide To Fiber Optics was created as a beginner's introduction to fiber optics. Over 60,000 printed version of Lennie's Guide were given away and it became one of the first commercial web pages in 1994. Uncle Ted's Guide To Communications Cabling was written a few years later to introduce techs to "Cat 5" - UTP wiring - that had only recently been standardized in TIA-568.

Lennie and Ted's Guides are used in the current Fiber U online self-study programs and are still the best place to start learning about fiber optics.

Lennie and Uncle Ted's Guides are online at the links here, can be downloaded as printable PDFs and are now also available as free iBooks on iTunes.

Lennie Lightwave's Guide To Fiber Optics   Uncle Ted's Guide to Premises Cablling

Lennie Lightwave's Guide to Fiber Optics and Uncle Ted's Guide To Communications Cabling   are now available free to iPad users who can download them from the Apple iTunes store. Of course they are still available online or for download.

You can also find these free guides on the FOA website - go here for all the links: Lennie Lightwave's Guide to Fiber Optics and Uncle Ted's Guide To Communications Cabling  

Download PDFs of Lennie or Uncle Ted.


FOA iPad Apps

FOA LossCalc
FOA Loss Calculator AppFOA LossCalc estimates the optical loss of a fiber optic link. This will save time for the installer of a fiber optic link needing to know whether test results are reasonable and/or make a "pass/fail" determination. It can also help the designer of a link to determine if communications equipment will operate over this link.
By choosing the type of link (singlemode or multimode) and specifying the length of the fiber and numbers of connections and splices, it will calculate the end to end loss of the link. The app has default specifications for singlemode and multimode links or the user may create custom setups with specifications appropriate for any application.

Self -Study in Fiber Optics
FOA iPad AppOur first app is a self-study version of the FOA Reference Guide to Fiber Optics. The FOA APP builds on the FOA basic fiber optic textbook to create an interactive learning environment that builds on the iBook electronic version of the book to add a guide to use for self-study and real-time testing that provides feedback on what you have learned and correct answers to questions answered incorrectly.
The FOA APP is priced at only $9.99, same as the iBook, so the self-study program is free. Download it from the Apple APP Store with your iPad or iTunes.



The FOA has many videos on videos, including two Lecture Series (Fiber Optics and Premises Cabling), Hands-On lectures on both and some other informational and instructional videos. For all the videos, go to the FOA Channel "thefoainc" or use the direct links below.

View a complete list of FOA Videos with links to each video on YouTube.

Where Are The Jobs In Fiber Optics? FOA talks about all the applications for fiber optics, what jobs involve and the qualifications for the workers in the field.

Fiber Optics - Live!  A series of videos that use lab demonstrations to show how optical fiber works. 
Fiber Optics LIVE!

Cabling Project Management - what's involved in a copper/fiber/wireless project -advice for the customer and the contractor

Hazards Of Counterfeit Cable

You may have read the stories we have written about the counterfeit "Cat 5" cable made from copper-clad aluminum rather than pure copper. Recently we tried an unscientific burn test on the cable compared to a known good UL tested cable and posted a video on YouTube. You can see the results below.

Counterfeit cable flame test

Counterfeit Cable     Real UL-rated cable

The difference is obvious and the danger is real. Watch the video on YouTube: Premises Cabling Lecture 11: Counterfeit Cat 5 Cabling

View a complete list of FOA Videos with links to each video on YouTube.

View all the FOA Channel  on YouTube.  


FOA Guide

What's New  in the FOA Online Fiber Optic Reference Guide?

We are continually updating the Online Reference Guide to keep up with changes in the industry and adding lots of new pages of technical information. Go to the FOA Guide Table of Contents to see the latest updates - look for New.

Find What You Want Using "Google Custom Search
custom searchThere's so much information on the FOA Tech Topics and Online Fiber Optic Reference Guide that even a well-organized Table of Contents isn't enough and when the material is always changing, an index is impossible to maintain. So the FOA is using the latest technology in search, Google Custom Search, which will allow you to search just the FOA Tech Topics and Online Fiber Optic Reference Guide for any topic you want to find more about. Try it!  

Go to  The FOA Online Fiber Optic Reference Guide.


New Schools
The FOA welcomes the newest additions to our listing of FOA-Approved Training Organizations:

The FOA network of training organizations offering CFOT (and more) certifications continues to expand. We welcome six new schools from quite different backgrounds - a manufacturer, an electrical JATC and several independent trainers.

Affiliate School:
Capital Commitment of Virginia, Fairfax VA
The FOA Fiber U Affiliate program is for non-commercial schools which wish to offer training in fiber optics or premises cabling without offering certifications. Typically this involves technical high schools or colleges offering telecom or IT programs where the school would like to have a curriculum module on cabling infrastructure which is usually missing from these subjects. It may also be appropriate for job retraining programs. 

Find a listing of all the FOA-Approved schools here.

Find An FOA-Approved Training Organization

Most inquiries we get regarding finding a FOA-Approved training organization want to know two things: what school is closest to me or what school offers the certifications I need. The FOA has about 200 training organizations we have approved worldwide so finding the right one can be difficult! We've been looking at ways to make it easier, and we think we've got a good solution. In fact we have two solutions.

First we have added a sortable table of all the FOA-Approved schools.

You can also use our FOA Google Map to find FOA-Approved schools.


What Should A Fiber Optics or Cabling Tech Know and What Skills Do They Need?
FOA certifications are based on our KSAs - the Knowledge, Skills and Abilities that techs need to succeed. Read the FOA KSAs for fiber and cabling techs.

School News


We always enjoy feedback, especially when it shows how great some FOA instructors are. These came from students of Tom Rauch, an instructor at BDI Datalynk:

"I took your fiber optics certification courses this past March. I just wanted to let you know that in two weeks I start working as a fiber optic technician with ___ up in ___. You mentioned on the first day of the course that there is always one guy in class who had rubbed his last two nickels together to be there and, in that instance, I was that guy. Now I'm going to be able to provide for my family like never before and I owe it to the certification that I received from you and BDI Datalynk. I just wanted to thank you again."

"Thanks to our tremendously knowledgeable and patient instructor Thomas Rauch, who was not only generous in sharing his wealth of information, but he did so with ease, humor and in a way that invited curiosity and participation. He was encouraging and proud of our accomplishments and helped us learn from our mistakes in a way that did not break our confidence, rather it pushed us to better results the next go around. The hands on labs were just AWESOME!" Just thought you should know what a class act you have representing you in his travels..... but then again you probably already knew that! : )

In almost 19 years at Verizon and having held numerous positions, I have gone through many training sessions. I cannot remember ever having been actually looking forward to coming back to class quickly after lunch, to get back to the hands on activities, and walking away with the sense of empowerment that the information presented was not only relevant but dead on point accurate! I will be signing up for the Outside Plant class on March! I can't say enough good things about Tom and his impact! Feel free to quote me, I can only imagine that he will open so many doors and change so many lives in the years to come, with his style of teaching! Great experience, awesome job!

IBEW and FOA Partner on Fiber Optic Training

The International Brotherhood of Electrical Workers (IBEW) and the National Electrical Contractors Association(NECA) through the National Joint Apprenticeship and Training Committee (NJATC) in a partnership with the FOA has published a new textbook for training IBEW apprentices and journeymen in fiber optics. The new textbook uses the material from the FOA Reference Guide To Fiber Optics with new material and photos from other NJATC training partners.

NJATC FOA Textbook

Quote from one of our certified instructors: I want to thank you and your organization for all the resources you provide for the students and the opportunity to offer the certification to the students. The fact that you published the book yourself to get the cost down and the unlimited free resources on your website shows a commitment to the public that is second to none. I let it be known to the students that the FOA is the best in the industry at supplying knowledge and resources related to the communication industry. I look forward to passing on the information that you provide for the industry.



Good Question! Tech Questions/Comments Worth Repeating

Real Questions From FOA Newsletter Readers

Terminate All Fibers Or Just Some?
We are currently running fiber which will be 12/24, my question is do we need to terminate every pair even if we aren't going to be using them or is there an alternative?
No you do not need to terminate all of them and leaving some bare fibers is often done when there is no planned use for the fibers or to save money. However, there are some other issues to consider. You do need some spare fibers ready to use, either in case of problems or for upgrades. For small fiber counts, the cost of terminating them all at once will be cheaper than having to come back to the site and doing it in the future. The economics are quite different if you have 144 or more fibers, of course. If you leave bare fibers, be sure to leave enough length to terminate or splice later - about a meter for termination and 2m for splicing. And protect them from damage so they can be used in the future.

OTDR Calibration
I know user who want to send their OTDR’s in for calibration, especially those that do government work.  Are you aware of a check list of the required tests to comply to what would amount to an “OTDR Calibration”?
ORDR calibration is covered on FOA Guide page on OTDR FAQs -   OTDR calibration is a unsolved problem. I was first involved with it at NBS in Boulder (now NIST) in the mid to late 1980s. They could not justify having a set of “golden fibers” to send around because they could not figure out how to make a “better" OTDR to use as a standard as we/they did on fiber optic power meter calibration.
Later some tried building electronic calibrators that could calibrate the timebase and linearity of the receiver, but that ignored the laser transmitter - you would need to calibrate it’s wavelength also. Wavelength variation could cause up to 3% difference in backscatter and loss measurements alone. Then the OTDR allows for changing the index of refraction to different fibers which affects length measures.
At one time some manufacturers looked at OTDR cal systems but the only electronic cal units for OTDRs I know that made production came from Belarus. There is a single system in the Navy at Corona, CA however.
Bottom line, test it’s operation according to manufacturer's spec.

Variations In OTDR Length Measurements
I am performing OTDR testing using 3 different wavelengths (1310, 1550, and 1625) on the same fiber but I get 3 different results for fiber length.  The test set and testing parameters do not change.
A: The OTDR calculates length by measuring the transit time to an event (half the total time since it measures the pulse time both down and back) and multiplies it by the speed of light in the fiber. Speed = C(speed of. Light in a vacuum) divided by N(the index of refraction of the glass). Most fibers have an N~1.46.
In an OTDR that speed of light is set using index of refraction in the setup parameters. In the fiber, the light actually travels at different speeds according to the wavelength of light - that is what causes chromatic dispersion. For Corning SMF -28 SM fiber,  effective refractive index at 1310nm is 1.4674, and at 1550nm is 1.4679, not much difference but adds up at 10km or more.
So your OTDR probably has the wrong setup. 

Connector Mating Adapters
: I am looking for a standard that describes the value of parameters (IL, RL) and class (if we can talk about class) for FO mating adapters.
A: Mating adapters are part of the connection but like each connector they only contribute to the total loss of the connection and cannot be separated from the other two when talking about loss. They can be specified by mechanical dimensions and materials. For example on 2.5mm ferrule connectors (SC, ST, FC and the obsolete FDDI and ESCON duplex connectors) the mating adapters have had alignment sleeves made of molded glass-filled thermoplastic, phosphor-bronze and ceramic. The plastic ones are cheap but wear out quickly - 10 insertions will leave plastic dust all over the mating connectors. Phosphor-bronze mating adapters last longer - maybe 500 cycles. The ceramic sleeve ones last almost indefinitely. We know this because we were in the test equipment business for 20 years (we started FOTEC in 1980 and sold it to Fluke in 2000) and we tested these mating adapters for longevity with reference test cables used in insertion loss testing. We had many calls from techs with problems caused by the adapters with plastic sleeves. So the way we know the mating adapters are graded is by alignment sleeve materials.

Removing Old Fiber
I have several 1000 feet of old 62.5/125 armored fiber optic trunks under a raised floor that I am replacing/upgrading to 50u MM and SM trunks. Is there any guidance on ‘Best Practices’ to follow when cutting these trunks into more manageable lengths for removal?
A: Use a jaws-type cutter to cut the cable into reasonable lengths and remove it. There should be no danger in cutting the cable up as long as your workers only cut the right cable. Raised floors often have large numbers of cables - often including power cables - so its important to ensure the proper cables are being cut an removed.

APC Connectors
With a fiber optic pathway that has multiple patching points...if the end user requires APC connections, isn't it only important to have those angled connectors at the end/equipment connections with UPC being acceptable throughout the middle part of the link?
A: Reflectance at the connection is the issue, of course.
Reflectance near a transmitter can affect the laser transmitter causing nonlinearities or noise in the device. That’s always been a major concern.
The second issue is reflectance causing background noise in the link. If you have ever seen a ghost on an OTDR, you have seen a reflectance at a connection that is bouncing back and forth in the fiber and is of high enough amplitude that you can see it at the source. Of course if it reflects back and forth in the fiber link, it will also show up at the receiver end, becoming noise and/or distorting the receiver pulses. In a bidirectional single-fiber network like a PON, it affects receivers at both ends.
Some refer to this as multipath interference. It is being studied by international standards groups but nothing has been published on it as far as I know.
We are familiar with a link that was ~1km of SM fiber with hand-polished ST connectors at several connections. The link had acceptable loss for all the fibers in the cable but none would work with electronics. Replacing the connectors with fusion spliced pigtails cleared the problem up immediately. Was the problem
With that background, I would answer you question this way. APC connections at each end of the link will effectively stop any reflectance issues going back and forth in the whole link. Using UPC or PC connectors in the link with reflectance better than -40dB are unlikely to cause problems. (Keep them clean of course since dirty connectors show high reflectance.) If the links are very short (<1km), the fiber will not attenuate any reflectance substantially, so short SM links (FTTH and passive OLANS for example) often use APC connectors everywhere.
And a final practical issue - mixing APCs and PC connectors is very bad, perhaps damaging the surfaces. If you do mix them in a link, you must train personnel how to handle them. If you have patch panels with PCs and equipment with APCs, for example, you have to ensure the patch cords are color coded properly (blue = PC, green = APC) and everybody knows not to mix them

What Do Testing Results Indicate?
I was told the other day by a network technician that it is possible that a fiber optic strand that is tested to standard, 850, 1300, mm and 1310-1500 SM bi-directional can pass a test but when connected to an optic it doesn’t work. I told him that the optic is the variable but if a strand passes the testing its qualified to “work”  or pass light.
A: There are several reasons it can be true.
Either MM or SM
-The installed cable plant is OK but the patchcords are bad. Or mixed up - we know instances where systems did not work because MM systems were connected with SM patchcords and vice versa - instant 17-20dB loss.
-The polarity is wrong so the transmitter does not go to the proper receiver. For MPO networks, this is a major problem since there are so many different polarities used. (See MPO array/parallel connectors and how to test them). This is often a documentation problem.
-Post testing, the connectors get contaminated and not cleaned or are damaged.
-The link meets the loss budget but the length is too long for the fiber type to support the transmission bit rate - e.g. OM2 fiber  on a 10G system that is near 300m long (see Specifications for fiber optic LANs and Links for the list of lengths supported)
-Mixing PC and APC connectors. Bad for loss - may cause serious damage too.
-Reflectance problems. Interestingly this question was asked this morning by the tech boss at a giant university. Here is the question and my answer:

Connector Loss At Patch Panel
If I have two SC connections in a cabinet eg one incoming cable jumperd to an out going cable. Should I be looking for a loss of no more than .75db across the two of them as per TIA-568
A: TIA 568 has included a connector loss of 0.75dB for decades. Even the committee is aware that this is a bogus number for most connectors but they leave it in because the manufacturers of MPO connectors need it to comply with the standard.
SC connections should be ~0.2-0.3dB if the connectors are good and properly cleaned. Now in the patch panel you describe, each of the two connections should be in that range for a total loss of 0.2-0.6dB. TIA would allow 0.75dB for each connection or 1.5dB total.

Differences In Fibers
What is the difference between OM3 and OM4 type fibers and G.654/G.655? They seem to be rated for the same  amount of GBs (10-400) and the only difference seems to be the multi-mode nature of OM3/4 vs. the single mode nature of G.654/655. Can they both be used in long haul communications if laser optimized?
A: OM3 and OM4 fibers are both 50/125 micron fiber but have different bandwidth capability. OM3 is rated at 1500MHz-km while OM4 is rated 3500 MHz-km. OM4 is an evolution of OM3 where design and manufacture allow more bandwidth. More bandwidth translates into slightly longer link lengths in faster networks, ~1-10Gb/s. For example, Ethernet at 10Gb/s will go 300m on OM# and 450m on OM4, which can be important if it is being chosen for a enterprise network backbone.
The differences in G.654 and G.655 are more complicated. G.654 is singlemode fiber optimized for use at 1550nm for long distance use. G.655 is “non-zero dispersion shifted” fiber tweaked for dense wavelength division multiplexing (DWDM) to prevent secondary problems with high power and closely spaced wavelengths of DWDM and fiber amplification. It’s the kind of fiber used in long submarine cables.

From Feb 2018

Testing At 820 or 850nm
I am working on calibration of an optical power meter. It is an old Photodyne 2285XQ and I need to test it at 820nm, I believe this wavelength is (or used to be) fairly common in military applications. The problem is the only equipment I have available is  all based around 850nm/1310nm/1550nm. Our optical power meters and optical spectrum analyser can certainly operate at 820nm, but I’m having real difficulty finding a commercially available light source at 820nm.
A: That Photodyne meter was probably built before the US National Bureau of Standards agreed around 1983 to create the first calibration standards for fiber optic power meters. NBS created standards for the three primary wavelengths of fiber optics - 850, 1300 and 1550nm - based on the available laser wavelengths for calibration with their standard ECPR - electrically calibrated pyroelectric radiometer.  The 850nm range was never considered a problem because in the early days LEDs were sometimes called 820nm and sometimes called 850nm, but the spectral width is quite wide and the variation in actual peak wavelength, even as called out in standards, is 850+/-30nm or 850+/-20nm, making it a very “broad” standard.
I know the rules for MIL standards and calibration so here are several solutions. Your solution will require a transfer from some transfer standard power meter.
1. Use the 820nm laser and calibrate the output with the H-P set at 820 if that is possible. Possible error due to calibrating only a small spot on the Photodyne detector.
2. You can also make the cal above with a high-intensity source with a filter around 820nm.
3. Use an 850 LED and calibrate the output with the H-P set at 820 if that is possible. This assumes the photodetector sensitivity curves are similar.

Negative Loss?
We were sent this OTDR trace and asked why some traces showed negative loss - gains.
The issue with this OTDR test of a factory-manufactured patchcord was not straightforward. To summarize, the patchcord was plugged directly into the OTDR port, with no launch cable. The OTDR has no reference for measuring the loss of the first connector on the cable nor the second connector since neither launch or receive cables were used. Without a launch cable, the OTDR is trying to get information from the connection to the instrument itself which is basically impossible since it’s suffering from overload caused by the test pulse - even with APC connectors. The OTDR (Yokogawa) is one of the cleanest OTDRs at the interface (we have one on loan at FOA right now) but it’s still not designed to measure that loss. Furthermore, using the instrument interface to plug in every connector will wear that connector in the unit out quickly and require servicing by the factory. The second issue is the difficulty of measuring on short cables like this. Note the vertical digital resolution of the display and think about the location of the second marker - it’s measured dB value will jump around as it goes from digital segment to the next digital segment. When you use a launch cable and measure the loss of the connectors using the “4-point” measurement - also called “least squares approximation” in the FOA Guide to OTDRs. That will overcome the digitization errors as well as the settling times of the pulses.

POTS over Fiber
I would like to know if there is information on your website that explains "POTS OVER FIBER"?
A: POTS - the acronym for “plain old telephone service” - is digitized to transmit over fiber. In the early days (late 70s and 80s) it was simply T-carrier with a fiber converter. By the end of hte 80s it was ATM and SONET. More recently, it’s all going to carrier Ethernet since 99%+ of the traffic is data not voice or PONs (passive optical networks) for fiber to the home.

Re-routing Old Fiber Optic Cables
; I have a questions about the re-routing of fiber optic lines that have been in place for a number of years.  Is it a standard transaction in the fiber optic business to have to re-route fiber that has been in service for a long period of time.  (e.g. >20 years)  If so, is there a best practice for removal from conduit for re-rerouting?
A; There is no way we would recommend removing and reinstalling 20-year old fiber cable. First of all, old cable may be damaged in removal. Then cable and fiber technology has improved over the years so you can get much better components today at greatly lower prices. (One industry analyst I know likes to say that fiber is cheaper than kite string and fishing line!) Today’s cable designs allow for much smaller cables with many more fibers (288 fibers in 9.7mm - just over 3/8”) and new conduit designs allow for more cables in a conduit (microducts and cloth ducts) and easier installation - blowing in cables and microtrenching are perfect for metro areas.
More fibers, especially in a big city, is a must. Smart cities, small cells, FTTH (fiber to the home), ITS (intelligent traffic systems), V2X (vehicle to vehicle, infrastructure, etc.) and many other services need lots of fibers.
Our recommendation is to pull it out and dump it. Install new ducts and the fiber you need (x10 maybe?) and have new ducts for future use. Are you familiar with “Dig Once”?

APC Connectors On Power Meters
We need to test a fibre link terminated with APC SC pigtails. I am using SC-APC Ref Leads to interface the LSPM to the fibre link. I am using the 1 Test Cord Method. Step 1 means connecting the LS to the PM via one Ref Lead. That means I have an APC Green SC connector plugged into the PM.  Is that OK? 
A:The SC APC connector should only be mated to another SC APC connector to prevent potential damage to the fiber/ferrule end. But most power meters have adapters for the connector that have an air gap above the detector to prevent contact to the detector window. Plus, the detector should be large enough to capture the light from the SM fiber exiting at a small angle. Thus you can plug the connector into the power meter directly.
Some meter manufacturers make SC APC adapters for their power meters that angle the connector toward the detector but that is generally not necessary unless the meter has a very small detector.
However if the power meter has a pigtailed detector - that is the meter has a fiber>fiber interface, you will need to add an adapter patchcord to mate the APC connector to it. When you set a 0dB loss reference all those connections will be zeroed out.

Directional Testing
I have taught for several institutions and throughout all my years of doing this I was always taught that when testing for insertion loss and back reflection for singlemode cable links that testing bi-directional is an imperative.  Recently when I was attending a meeting involving members of the military along with folks involved in the development of the military manuals, it was mentioned that with singlemode testing that bi-directional testing is not necessary.
A; First of all, there is a directional difference in splice or connector loss - and maybe reflectance (that term is now almost universally used in place of “back reflectance” which is a poor term since a reflection is always back) - as long as two different fibers are being spliced. Fiber geometry is the main difference - mode field diameter in SM and core diameter in MM - but it can also be a matter of the fiber composition.This happens if two different manufacturers’ fibers are joined or bend-insensitive (BI) fiber with differences in depresssed cladding geometry are joined.

If you test bidirectionally with sufficient accuracy, you can see the difference. It’s an OTDR trace that most people are familiar with  -  if you see a gainer, you shoot the other direction and average to get the “actual” splice loss. When splicing or connecting different types or manufacturers SM fiber you may see directional differences of up to 0.3dB or more. Same for MM, not only for differences in core diameter but also for connecting BI to non-BI fibers. While those OTDR measurements are actually differences in backscatter levels, they are indicative of real differences in connector loss or splice loss in opposite directions.

Are those differences enough to be of concern? That’s a judgment call.

We’ve found most people do their bidirectional testing all wrong. With an OTDR, you should disconnect the instrument, not your launch and receive cables, and take just the instrument to the other end. Disconnecting the launch and receive cables changes the fibers at the connections to the cable under test and you lose the connection you want to test from the opposite direction.

Bidirectional testing with a test source and power meter is more confusing. You have to do your “0 dB” reference, check the launch and receive reference cables, measure the cable under test, then move just the source and meter to the other end, test the cable under test again, then disconnect and then measure the output of the source to get the “0 dB” reference used in that direction. That’s confusing!

Even if you do test bidirectionally, you do not get the “actual” connection or splice loss like everybody says - you get the average of the two directions. Unless you are willing to do a lab setup and some careful testing, that’s the best you can do.

Now we are into measurement uncertainty. If the measurement uncertainty is around the same as the typical bidirectional difference, does bidirectional testing gain you that much?

That’s a judgement call.

The new FOA book on testing goes into this - a complete chapter is devoted to measurement uncertainty.

FOA textbook on fiber optic testing

When To Test Fiber
Should testing of the fiber plant be done before the Optical Network Terminal is installed?
A: Fiber optic testing is generally done when the cable plant is installed to confirm proper installation and check that the performance is adquate for the electronics planned for use on it.
There are several processes - first an overview of testing:
Check cable before installing - continuity if it looks OK, OTDR testing if the reel is damages
Test installed cable when splicing - check the fusion splicer estimate of loss and do OTDR testing if questionable and inspect every connector as termination is done to confirm the connector is good.
Test cable plant after splicing and termination - end-to-end insertion loss and OTDR testing for longer OSP (outside plant) links.

New singlemode cable plants for high speeds may need "fiber characterization” - adding in CD (chromatic dispersion), PMD (polarization mode dispersion) and SA (spectral attenuation for DWDM wavelengths) testing. If one is considering upgrading a cable plant that is already installed or has been used, these same tests should be done - inspection/cleaning, insertion loss, OTDR.
When the system is installed, one should know it should work because of the testing done during installation. One should inspect and clean patchcords before installation and test them if suspect. In fact any connector needs inspection/cleaning before hooking up equipment. Dirt is the biggest problem with fiber optic systems.

Differences Between Singlemode or Multimode Mating Adapters
What is the difference between singlemode and multimode bulkhead/adapters (mating adapters). My understanding is you cannot use the singlemode with the multimode and visa versa.
A: There are 3 types of adapters - rated for SM or MM - based on the alignment sleeve material.
-Plastic (glass filled thermoplastic) alignment sleeves are cheap, not very precise and wear quickly (you can see ceramic ferrules get dirty using them) - only good for multimode and one or two insertions - not recommended
-Metal (phosphor bronze) alignment sleeves are better with good alignment but still wear some - OK for MM, some are rated for singlemode (check before you buy), and are OK for most uses but will wear out if used for repetitive testing
-Ceramic alignment sleeves are the best and most expensive. They are very precise in alignment and last for a long time. Recommended for all singlemode and all testing purposes.
Don’t use MM adapters for SM but SM adapters are OK for MM.

Why A Figure 8?
What is the reason for wrapping the cable in a figure eight?
When you need to do an intermediate pull, you have to pull the fiber and coil it on the ground. A simple coil will put a twist in the cable. Figure-8 coils put in twists of opposite directions on each side of the 8 making for no overall twist in the cable. See How To "Figure 8" Cable For Intermediate Pulls in the FOA Online Guide.

Can I Build A GPON Network With "Taps"?

Q: Can I build a GPON network where I do a drop to one subscriber then continue to the next subscriber for another drop and so on?
A: There have been examples of this type of “tap” drop proposed, for example in rural areas for drops to  widespread subscribers on a longer network than is typical for FTTH. It’s just a version of a cascaded splitter network. with taps that just do a 2 way split. The taps used are typically 90/10 taps, where 10% of the power is tapped off for the drop.
There are some important issues to consider - Since you are dropping 10% of the power at each tap, you are limited by how many drops you can have.   If you calculate the loss budget - after the first tap, you have 90% power left less the excess loss of the splitter (~0.3-0.5dB). The tap power is down ~10.3 dB and the through power is down ~0.6 dB. At the next tap, you  use the same formula plus you add the loss of the fiber to that tap and so on until you reach the GPON limit.  It’s a pretty complicated process to design, but you can see that with these power losses you will not get a large number of drops in a GPON network with 28dB max power budget. We did a rough calculation and 20-24 drops may be possible depending on the fiber lengths.
This network will probably be much more expensive and more distance limited than simply running a cable with many fibers and dropping fibers from that cable with midspan entry. Couplers are expensive, fiber is cheap. We also do not know the issues with the large differences in transmission times between the first connections and the last ones, which depends on the length of fiber in the systems. That may require some programming at the OLT.

Replacing OM1 MM Fiber
Q: We are an automation system integrator in South Africa. We have a client that has multimode 62.5/125 fibre optic plant wide. None of the runs between components are longer than 2km. We intend to upgrade the technology from a proprietary communication protocol to a standard ethernet protocol at 100 MHZ. The fibre to copper convertors we will be using are using 1300nm light source and have a Fibre Optic Link Budget of 12.8dB for 62.5/125 um and 9.8dB for 50/125 um. The client has been advised to replace the multimode 62.5/125 with multimode 50/125 cabling and we need to know if this is really a requirement.
A: Do you know how old the fiber is? It should be what we called FDDI grade 62.5/125 fiber with a loss of ~1dB/km and a bandwidth of 500MHz-km at 1300nm. A 2km link should have a loss of 2dB for the fiber and ~0.5dB/connection - well under the power budget of the link. 100Mb/s Ethernet variants were designed for 2km or more on this fiber. There is no reason to upgrade at this time, 50/125 fiber would not be needed until Gigabit Ethernet was desired.

Do We Need Repeaters For 30 Mile Link?
Q: I need to design a 30 mile (~50km) link. Will regeneration like a fiber amplifier be necessary?
A: It depends on the comms equipment but I doubt you need regeneration. 30 miles is 50km, only 10dB of loss for the fiber at 1550nm, maybe 10 splices at <0.1dB adds only 1dB loss and another dB for connectors on each end. I think you probably can find equipment that runs on 12dB loss budget. That said, most new high speed systems (>10G) have 20km versions then go to expensive long haul coherent systems. So talk to the communications equipment manufacturers and see what they say. If you do need a EDFA, they are not that expensive but the site is expensive and requires power (+ backup). See if it’s possible to put the EDFA in the end facilities to get enough power for the whole run.

Testing PCS Fiber
We Get Many Questions From Our Instructors Also

Q: I recently did a CFOT training class for a government agency.  They use 200 micron core fiber in short sections (50 ft. the longest) within aircraft. The connectors are SMA 905s.  The cable specs state that there is 8dB of loss in 1 km at 850nm. I have searched but cannot find any info regarding how to test the cable/connector links.  The OLTS they have uses 62.5/125 jumpers. Is testing these cables with the above OLTS setup at 850 nm a valid testing method?

A: That’s 200/240 PCS or HCS fiber - plastic clad silica or hard clad silica step-index fiber - that has a glass core and plastic cladding. It has been used on a lot of platforms because it’s large core makes connection alignment easy. The SMAs are used because the connectors are air gap connections so vibration will not cause scuffing that you can get with PC - physical contact connectors. On aircraft, the 1/4-36 nuts on the SMAs are usually safety-wired too.

Testing can be done just like any other cable plant with a double-ended test (OFSTP-14) for the whole cable or a single-ended test (FOTP-171) to check the connection on either end. You need a 850nm LED source and a meter with a large detector (>2mm) to pick up all the light and an adapter for SMA connectors. You also need launch and receive cables of matching fiber and connectors about 2m long. No worries about mode conditioning since the step-index fiber is a mode mixer itself.

Fiber attenuation coefficient of 8 dB/km sounds about right. Connection losses ~0.5-1.0 dB are normal. A typical patchcord would have a loss of ~1-2 dB.

To get a microscope to view it might be difficult.

VFL for 10km?

Q: I have 10 kilometers of singlemode cable installed that was not labeled. It has been suggested that we shoot a VFL down the fiber and label it. I am having trouble finding a VFL that will shoot this far. Any ideas?
A: Occasionally we see some imported VFL that claims to go 10km or more. That tells us the company is clueless about fiber optics. VFLs work at ~650nm in the visible red spectrum while SM is optimized for 1300-1600nm in the infrared where it has a loss of ~0.3dB/km. At 10km it has a total loss of ~3dB or half the input signal. At 650nm, singlemode fiber has a loss of ~10dB/km which means it loses 90% of its power per km. At 10km, you have 100dB of loss - leaving you with 0.00000001% of the input power - not much!
VFLs have enough power for 2-3km max. To identify fibers at 10km, you need a 1310nm laser source and a power meter to do continuity. Or a gadget called a fiber identifier. For more info, see and

Connecting WiFi Access Points In a Passive Optical LAN

Q: If we install GPON passive fiber optical LAN in a new hotel, would one need to run fiber to every AP? Since every hotel room needs an AP this gets expensive. Any suggestion on the simplest and less expensive  way of connecting Fiber Cable to an AP in the hotel room?
A: You do not need a fiber to every wireless AP in a GPON passive optical LAN (POL). The AP needs a UTP (Cat 5e/6) cable with Gigabit Ethernet and  POE (Power over Ethernet) capability. The POL fiber  should terminate in a multiport switch that has a fiber input and then 4 or more UTP/POE outputs for the wirelses APs. That’s the cost saving architecture of a GPON POL. See this page in the FOA Guide:

You should also check out the APOLAN website ( for more information on hospitality applications with POLs.

Wireless Infrastructure

Q: I am wondering how the landscape will change as the nation moves from 4G-LTE to 5G. Will it use the same network as currently, or will the network need to be updated or replaced? To what extent will 5G be dependent on wireless vs fibre optic? Will the infrastructure nationally move more toward an underground wired one, rather than a Radio Access Network?
A: The wireless network is totally dependent on fiber optics for it’s communications backbone. The “wireless” part is the connection from an antenna to the mobile device. From that point, the network is cabled, mostly fiber already and soon to be all fiber.
4G/LTE and soon 5G in urban areas is moving to “small cells” with about 10X as many cell sites covering much smaller areas. Every small cell site needs a couple of fibers. Metro backbones will require very much larger fiber counts, especially with C-RAN (centralized radio access network) architectures now being implemented.
An example is Santa Monic, CA where we live. It has about 200K citizens, 8.9 square miles(about 23 sq km), but has planned for 600 small cell sites, spread over multiple service providers.

At FOA we see wireless as one of the most active areas for fiber, along with data centers.See

OTDR Setup

Q: What are good OTDR settings for a 300-500m fibers? We’re using a 1.5 m launch cable and sometimes got (-) loss,
A 1.5m cable is not a launch cable. A launch cable must be long enough to allow the OTDR to settle down after the test pulse. THe negative loss is because the OTDR has not settled down sufficiently.
Generally the minimum launch cable for testing short cables would be 10-20m for MM, 100m for SM. Then use the shortest test pulse, ~1km range, average enough to reduce the noise.

Arsenic Coated Cable?
  I was told a contractor installed arsenic coated fiber optic cable because they didn’t want animals to chew through it. Is this true?
A: Some cable has chemicals put in the jacket to make it taste bad to rodents. We have not found any one who claims to use arsenic, in fact, we could find no references to what kinds of chemicals are used.

Why Do Cables "Go Bad"?
It’s been my observation over ~15 years of building and managing fiber channel storage area networks that from time to time cables will fall out of transmission spec.  In terms of communicating with non-storage people, they in essence, “go bad”.  Other than possible damage due to physical disruption of a cable, or contamination at the connectors usually caused by a human being unplugging/replacing, has it been your observation that MM cables can “go bad”?

A: There are some possible causes of problems over time. We know of connectors that fail for several reasons.
  • The biggest cause is with prepolished/splice connectors with mechanical splices. the assumed problem is the index matching get goes bad, but that’s highly unlikely. It’s usually the crimp fails and the fiber pulls out, especially if it has any stress on the fiber.
  • Adhesive connectors can have a bond between the connector and fiber fail, more likely on anaerobic connectors.
  • Any stress on the fiber at the connector is bad. Patchcords should not be left hanging on racks but dressed into horizontal racks below each patch panel.
  • Residual stress in cables can be a problem - tension or tight bends - and they may get worse over time.
  • Moisture is always a worry. It takes years to show up, but indoor cables are not protected from moisture like OSP cables.
  • Of course, transceivers fail too - electronics are generally very reliable but do deteriorate over time and cause failures.
We always say fiber requires no maintenance - set it up right and lock it up. As you pointed out human intervention is often the issue.

Fiber Ports Or Media Converters?
Should I Buy A Switch With Fiber Ports Or Use Media Converters?
A: I’m assuming you are thinking of using a switch with copper Ethernet ports and a media converter instead of a switch with fiber ports. The downside is that it adds complexity and increases the chance of failure. My analogy is something my primary flight instructor told me many years ago - multiengine planes are not safer because having two engines doubles your chance of having an engine failure. IBM still says that most network problems are cabling problems. Using media converters adds more electronics, more power supples and more cabling connections.

Testing PON Meters And Sources
We're evaluating PON power meters and test sources. How should we test them? Do we need a PON network?
A: There is no requirement for having a PON to test the meters. I would check it against a meter you trust to test
1) if the reading of absolute power (dBm) agrees - should be within +/-0.2dBm. Compare at several power levels, as high as possible (~0dBm with a laser), medium, (~ -20dBm) and very low (~ -40dBm)
2) make some loss tests of cables and attenuators over the range of 1-5-10-15-20dB and compare to a meter you trust.
3)the extra calibration at 1490 is not an issue - the difference between 1490 and 1550 is very small and providing that calibration can be more a confusion factor since there are no transfer standards for that wavelength.
3) The big issue with sources is stability. Connect the source with a short cable to a trusted power meter, connect it to its power supply, turn it on and monitor the output over time. There should be a short warm-up period and then it should be stable within a few 0.01s dB. Let it run on batteries until the batteries run down to ensure that the source has a proper power supply that keeps the light output stable over time as the batteries discharge.

High Loss At 1383nm?
We tested one link of 90.8 km at 1310/1383/1550nm and we got high loss at 1383 while other wave lengths have good results. What's up?
A: That wavelength is the center wavelength of the OH+ water peak, so you are seeing the extra attenuation there. Older fibers will have attenuation of 2-3 dB/km at that wavelength but new “low water peak” fibers will be <1dB/km. See “Low Water Peak Fibers” here

Polishing Films
  Are there different grades (micron) polishing films/papers for multimode and single mode fiber cables in ODF termination ? If yes, What are the grades polishing papers for multimode 50/125 um and 62.5/125 um fibers.
A: The polishing of MM and SM fiber is indeed different. Both start with an “air polish” with 12micron alumina polishing film to remove the protruding fiber. Then the polishing continues on a soft polishing pad (3mm 80 durometer rubber).
MM uses a 3micron alumina polishing film polished dry then a final 0.3micron alumina film polish. See
SM is usually done with a wet polish using as special polishing slurry and diamond polishing film. The diamond film will polish both the ferrule and the fiber to get the best end finish. See
There are even more pages of information on the FOA Guide at

Armored Indoor Cable?
Can I get an indoor armored 8 core fiber optic cable?
A: Most cable manufacturers make indoor armored cable using corrugated wrap armor to protect cables from crushing loads from other cables especially in under floor installations.

MPO Connector Loss
: Is there a current standard, for maximum allowable loss, for MPO fiber connectors? If so… what is the standard # from EIA/TIA? (Was it amended in 568B, since they were introduced?) Would it be similar to standard connectors @ 0.75dB Max allowable loss?
A: The MPO is covered under the TIA 568 standard. All fiber optic connectors are the same - 0.75dB.
There are discussions being held at TIA and ISO/IEC on using a different method of specification, statistical in nature, that says X% would be less than YdB in several stages from 0.1-0.2 to over 1dB, but it’s led to some headed discussions.
MPOs for MM are probably no less than 0.5dB and SM are near the 0.75dB mark. At least the SM ones are APC (usual 8 degrees, but still a flat polish).
I’ve recently learned that MPOs are polished for fiber protrusion to try to get fiber contact, but the evenness along the line of fibers is harder to control.

image from SUMIX showing protruding fibers in MPO connector

More Than “Single” Mode?
We're now using SM fibre so it looks like we don't need mandrels in the Ref Lead at the Light Source.  The info I have is that we need to make a couple of air coils 35mm to 50mm in diameter.  Why? 
A: When you launch from a pigtial laser source through a connector into a reference cable, you do have several modes being propogated. It usually takes 100m or so for the second or third order modes to attenuate. So the coil causes them to be attenuated by the stress enough to no longer be significant - it’s a mode filter just like MM. If you do not do this, you will measure higher loss in the fiber and at connections near the source. Since most SM has traditionally been long distance, the effect was small or ignorable, but with short links, it can be significant.
Followup Q: But how do we explain multiple modes in Single Mode fibre?
A: When you get the core of the fiber down to ~5-6 times the wavelength of the light, it no longer acts like geometric optics (like MM fiber). Some of the light can travel outside the core (see the note on “waveguide dispersion”here At launch, significant amounts of power are at higher angles creating short lived modes that are highly attenuated.

Replacing OM1 MM Fiber
We are an automation system integrator in South Africa. We have a client that has multimode 62.5/125 fibre optic plant wide. None of the runs between components are longer than 2km. We intend to upgrade the technology from a proprietary communication protocol to a standard ethernet protocol at 100 MHZ. The fibre to copper convertors we will be using are using 1300nm light source and have a Fibre Optic Link Budget of 12.8dB for 62.5/125 um and 9.8dB for 50/125 um. The client has been advised to replace the multimode 62.5/125 with multimode 50/125 cabling and we need to know if this is really a requirement.
A: Do you know how old the fiber is? It should be what we called FDDI grade 62.5/125 fiber with a loss of ~1dB/km and a bandwidth of  500MHz-km at 1300nm. A 2km link should have a loss of 2dB for the fiber and ~0.5dB/connection - well under the power budget of the link. 100Mb/s Ethernet variants were designed for 2km or more on this fiber. There is no reason to upgrade at this time, 50/125 fiber would not be needed until Gigabit Ethernet was desired.

Bi-Directional OTDR Testing
Should the testing be done with the same piece of equipment from both ends then merge the results or does that not matter - can you use traces from two OTDRs as long as the test equipment is compatible and settings are adjusted properly.
A: Yes, you should use the same test set from each end but this way - take a trace, disconnect the OTDR from the launch cable and go to the far end of the receive cable and connect it there to take the second trace. The usual way people do bi-directional tests is to disconnect the launch cable and take it to the far end and shoot back up, often not using a receive cable at all, figuring they get the far end connector on the second test. But when you disconnect the launch cable (and/or the receive cable) you lose the connection you want to test in the other direction! As for using the same OTDR, every OTDR is different and the results you get may be significantly different, esp. if they are not calibrated recently - and few OTDRs are ever calibrated.

Passive OLANs in Hotels And Resorts
Are passive OLANs a good choice for hotels or resorts?
A: Passive Optical LANs are enterprise networks based on fiber to the home (FTTH) technology not Ethernet over structured cabling. The FTTH network is usually using GPON standard equipment over one singlemode fiber with passive optical splitters that provides basic Level 1 and 2 network functionality. This is not Ethernet but carries Ethernet over the GPON protocols at 2.5G downstream and 1.25G upstream.
Passive OLANs offer several advantages over conventional Ethernet switches and structured cabling, including much less cost  (~50% capital expense and ~20% operating expense), much lower space requirements (see the link to the library photos below and note the two racks of equipment that support 4000 drops), longer distance requirements (to 20km), easy expansion (these are systems designed for hundreds of thousands of users) and easy management (when you have hundreds of thousands of users, that’s important.)
For hotels, convention centers and similar facilities, the ease of upgrading to a passive OLAN is a big advantage - one fiber goes from the computer room to a splitter where it can serve 32 switches of 4 ports each. That’s right, one fiber can support 128 users! It can support anything that a network can - wireless access points, security cameras, secure entry systems, VoIP phones or POTS phones - anything that will run over a conventional network.

Calibrating An OLTS
I have a question about the OLTS - do you have to recalibrate it every day ?
A: Any optical loss test set needs to be calibrated for “0dB” whenever anything changes - the launch cable - source output - or even every few tests to ensure the connector is clean and undamaged - plus they wear out. See 5 different Ways To Test Fiber Optic Cables.

Insertion Loss
I have not been able to find a good definition of “optical insertion loss” or “insertion loss” or “optical loss.”
A: Insertion loss was the term originally used for the loss of a connector tested by a manufacturer. They would set up a source and length of fiber connected to a meter, measure power, insert a pair of connectors and measure the loss. Since it was an inserted connection, it became known as insertion loss.
Over time, the term insertion loss became more widely used to contrast with the loss measured by the OTDR, an indirect measurement using backscatter that may not agree with the loss with a light source and power meter.
Insertion loss, therefore migrated to meaning a loss measured of a cable or cable plant inserted between the launch and receive cables attached to a light source and power meter for double ended testing used with installed cable plants. For patch cord testing, you do not use a receive cable attached to the power meter but connect it directly to the cable under test, making the test just include the one connection to the launch cable.
Two other terms often mixed up are attenuation and loss, which are essentially the same, except when discussing a fiber. In fibers, attenuation is often used instead of attenuation coefficient. Attenuation is the absolute loss i dB while attenuation coefficient is the characteristic attenuation of a fiber expressed in dB/km.
Here is probably the best explanations:

Old Fiber
We are looking at a company’s fiber network which has been laid at various points in time over numerous years.  In this process, we are trying to identify the changes that were made to either/both the glass fiber and the cladding.  Are there different generations of what was industry standard in creating the fiber?  For example, are you able to identify the difference in a fiber that was laid in 1980 versus one laid today?  Was the cladding the same size/thickness etc. in 1980 as it is today or has this been modified/improved upon over the years?  In all, we are trying to find what modifications have been over the years and how this may improve the life of the network and its capabilities. 
A: This is a common problem today. Many network operators are evaluating their fiber networks for upgrades, hampered by the fact that few are properly documented. Below is a timeline that should answer your questions. What many network owners are doing now is testing their cable plants - a process called Fiber Characterization.  There are contractors who do this service.
Fiber Tech Timeline
1976 - First field trials, US and UK, using multimode fiber at 850nm
1980 - First long distance networks still using multimode fiber at 850nm, planning to upgrade with wavelength-division multiplexing at 1310nm
1984 - singlemode fiber becomes feasible, telecom drops multimode fiber, all future installations are singlemode - this first SM fiber with a 9 micron core and 125 micron cladding is still available today but with better specifications. Really early fiber may not have good environmental protection and degrades over time. Early speeds were 145-405Mb/s, up to 810Mb/s by the end of the decade.
1990 - around this time, modern fiber begins - better performance and environmental protection. Fibers for wavelength-division multiplexing in the 1500nm range appear allowing multiple signals on a single fiber and fiber amplifiers allow long spans.
1995-2000 - massive build-out of fiber backbone leads to glut of fiber - WSJ ~2001 says 93% of all fiber is dark. Speeds grew from 1.2-10Gb/s over the 90s decade
2000-date - massive Internet growth and mobile device growth eats up glut of fiber and demands many times more. Dense wavelength-division multiplexing becomes the norm. Speeds began at 1.2/2.5Gb/s, upped to 10, 40 and are now at 100Gb/s.
So most fiber installed after 1990 has the possibility of being used at 10Gb/s, after 2000, it’s probably OK for 40Gb, and since 2010, you are probably OK for 100G and maybe more.  To verify performance, you test each fiber for connector condition, loss, spectral attenuation, chromatic dispersion and polarization mode dispersion. There are test sets that will do
Fiber Characterization in basically one step.

Fusion Splicing Live Fibers
Is it safe to fusion splice a live fiber, or is there a chance that
the light from the arc will damage the detectors in the modules at the end (20km-rated SM for us).
A: I have never heard of this being a problem. The amount of light coupled into the fiber from the splicing would be very small compared to a properly coupled laser. When a cable is broken you might be splicing the fibers that are live without knowing which are live and not caring. On your newer splicers this is not a problem. On the older splicers with the LID system you would have to reduce the power to get a good splice which they would do by putting a bend in the Fiber.

Duplex Communications Over One Fiber
Is true duplex over a single fiber possible, or is more like a shared time-domain technique in a quasi-duplex mode? I would guess that true duplex would lead to interference problems.
A. Bidirectional links are widely used - that’s how FTTH PONs work. They use splitters to combine/split the signals and one wavelength downstream and another upstream. See Fiber Optic Datalinks and for FTTH FTTH Architectures.

Using Hybrid 2.5-1.25mm Connector Mating Adapters
Can I use the hybrid 2.5-1.25mm adapters for connecting SC connectors to LCs or MU connectors. It would make testing much more convenient.
A: We do not recommend them for most uses, especially testing, as they can be highly unreliable. Reserve them for emergencies and use hybrid patch cords instead.

Test MM Fiber @ 1300nm?
Q: What is your opinion about the need for testing at 1300 nm on OM3 and OM4 fiber especially now that bend insensitive multimode fiber is taking over?
It’s unnecessary and costly. It’s rooted in the FDDI/100M days 25 years ago when 1300 LEDs were used and is now obsolete. The only actual uses at 1300nm I know are the extremely rare systems using 1310 lasers which may be standards but simply don’t seem to ever be used. As you say, BI fiber makes the issue of finding stresses moot.

Fiber In Service Loops
We designing a rural utility system that will be expanded to FTTH (or FTTR - fiber to the ranch in this case). We're wondering how much excess fiber in service loops to add. One software package is asking for 12% but that seems excess.
I have typically seen 100 feet on straight through boxes (reserves), 35-50 feet on cut ends for splicing and anywhere from 15-25 feet at the premise depending on how much is required for the termination device, positioning, etc. When rough estimating we have typically used 10% over linear distance.

Maintenance of Fiber Networks
Can you guide me how to prepare Optical Fiber Cable Annual Maintenance Proposal?
A: Basically, the network needs to be installed properly, fully tested and everything carefully documented. Then no routine maintenance is required. Most problems with fiber optic networks occurs when techs are working with it, e.g. damaging cables or getting connectors dirty when testing, so leaving it alone is the best plan.
Electronic transmission equipment can be tested anytime to ensure proper data transmission, but that does not involve accessing the fiber.
We have several things which may be of help:
You Tube Video: FOA Lecture 39 Maintaining Fiber Optic Networks
Web page: Maintenance

I have 4 questions about OTDRs:
What is dynamic range I read many time but can’t understand yet, whether it is a range of losses can be measured by OTDR for example if an OTDR has 45 dB dynamic range, it can read the losses of point up to 45 dB or what it means.
I do not believe there is a standard definition of dynamic range, but it is generally accepted to be the highest loss of the longest cable where you can see the end of the cable. That usually means using the longest test pulse and most averaging  and assuming the end of the cable has a significant reflection.

What is dead zone is it fixed in meters mean an OTDR cannot measure up to initial 5, 10 or 20 meter
The dead zone is a function of the pulse width and speed of the OTDR amplifier. For most OTDRs it’s about 2-3 times the test pulse width.

What Type of settings needed before launching a test
See FOA Lecture 18: OTDR Setup or the section "Modifying OTDR Setup Parameters For Best Test Results” in OTDR testing. A: Basically you set up wavelength(s), test pulse width (long enough to reach end of cable but short enough for best resolution), index of refraction or group velocity (a function of the fiber type and wavelength) and the number of averages (enough to mitigate noise but not take too long)

Reading a test with 1310nm and 1550nm - why values different for a same length of fiber.
The attenuation of the fiber will be different at each wavelength and the index of refraction which is different at each wavelength causes a difference in length. The OTDR measures length by measuring time and then multiplying that by the speed of light in the fiber (which is the inverse of the index of refraction.)

The FOA page "Frequently Asked Questions About OTDRs" answers these questions and more.

Getting Old Cables Out Of Conduit
How do you get old cables out of a conduit when they are stuck?
Usually we are concerned about reducing friction when pulling cables through conduit, but sometimes you need to get them out. Here is a page from American Polywater the leading lubricant company with advice on the subject.

Manufacturing Guide?
Is there a guide published by FOA that provides insight as to the process of fiber optic manufacturing? It's my understanding that the guide stresses quality and controls to ensure performance and reduce product loss?
A: We do have a guide for manufacturers. It is mostly aimed at communications systems and components manufacture. Here is a link to download it.

How Long Does Termination Take?

FOA received a request from a consultant recently wondering if we had information on the termination times for fiber optic cables. After some looking in our archives, we realized we had a document online that compared times for various fiber optic termination processes. The paper was written after several FOA instructors did a comprehensive time and motion study on termination processes. The document is about 15 years old but still relevant.

You can read it here in the FOA Online Guide.

Testing Connectors (From A Patchcord Maker)
What are the chief defining standard(s) that specifies connector and assembly IL (insertion loss) and RL (return loss or reflectance) for both SM and MM fiber?
A: The description on our Guide is here:  
FOTP-34 covers connector testing as a qualification test for the type of connector - basically a "destructive" test for connector manufacturers.
Reflectance is described on that page and here also:
Testing an assembly like a patchcord is covered under FOTP-107

Basic Tests For Fiber Optic Cable Plants
Q: I
did some research and I noticed that there is a bunch of tests that can be done to fiber optics and I was wondering if there is a list of primary tests that can be done as a basic test.
A: Fiber optic testing does have a hierarchy of tests.
  • At the top of the list is "insertion loss" testing which uses a light source and power  meter to test the fibers in the same way that a communications system transmits over the fiber. It is a simple test and the equipment needed is inexpensive.
  • Techs will also use a microscope to inspect the fiber optic connectors for dirt and damage, a big issue for fiber.
  • The instrument called an "OTDR" takes a snapshot of the fiber using a technique like radar. Most outside plant cables are tested with an OTDR and the data ( the snapshots are called "traces") stored for future reference. OTDRs are more expensive and require more training to use properly.
Here is a link to a page on the FOA Guide site that explains the technical,details:
FOA also has information just for users of fiber optic networks, see

How to Clean POF (plastic optical fiber)
Q: I heard that plastic fibres such as PMMA can suffer damage from cleaning from an alcohol solution. Are there alternate cleaning solutions available for these types of fibres."
A: You can use a 10/90 mix of  isopropyl alcohol/water. Typically use with a lint free swab. (from out POF consultants)

Testing Bare Fibers With OTDR
We are starting to test some OPGW cables. We have an OTDR but we don’t find some reusable connectors. If we have to test an OPGW with 48 fibres, we can’t set up 48 SC connectors!
Are there some reusable connectors in the commerce?
A: I assume you mean you need to test with a bare fiber on the OPGW. For testing bare fiber, use a splice, not a connector. Have a long pigtail on the OTDR as a launch cable, long enough for the test pulse to settle, say 100-500m, then use a splice for a temporary connection. You can fusion splice the fibers then cut the splice out or use a removable splice like the Corning Camsplice (
If you use a mechanical splice, you need a high quality cleaver just like with fusion splicing and after several uses, you need to add more index matching gel or liquid - mineral oil works OK.
See the FOA page on Testing Bare Fiber.

Is A Flashlight Test Adequate?

Q: I contracted a firm to install an OM3 of 200 meters. On one  end I have an SFP 1000SX ,on the other a 1000SX converter from optical to UTP. We made pings but they never reached, and I didn’t see the laser at the extreme of the fiber. They promised me to send me the certification they supposely made ,though they assured me the fiber is ok, because  WITH A FLASHLIGHT THEY SENT WHITE LIGHT FROM ONE SIDE TO THE OTHER AND IT WAS VISIBLE. I saw the light too, and I thought the culprit was my switch or my SFP. I want to know: is this a good demonstration that the fiber is ok?
A: A visual continuity test is not adequate - your eye is not calibrated! The power of the lamp is unimportant as each eye’s sensitivity is different. And your eye probably cannot see the light from a 850nm VCSEL source - most people’s eyes are not sensitive at that infrared wavelength. The installer should have tested the link with a light source and power meter ( and given you the loss in dB. The connectors should also be inspected with a microscope to ensure proper polishing and cleanliness ( If the SFP output is -6dBm, what is the power at the receiver? 1000base-SX is supposed to work with 4.5dB loss (see The fiber loss should be ~0.6 dB, so you must have >4dB connector losses! That says bad installation! The 1000SX link should work over 200m if the fiber has been properly installed.

Older Fiber?
I have some 62.5 mm and sm inside fiber plant over 20 years old.  When is a good time to upgrade?
A: When you need to or have to. If it's working OK, there is no need to upgrade!

"Connector Loss" or "Connection Loss"

Q: I have always counted the loss of a connector as .75 dB (568B-3) and 1.5 for a mated pair. Is that correct?
A: While the industry always says "connector" loss, it is actually "connection" loss. As we explain in the page on termination and splicing ( When we say "connector" loss, we really mean "connection" loss - the loss of a mated pair of connectors, expressed in "dB." Thus, testing connectors requires mating them to reference connectors which must be high quality connectors themselves to not adversely affect the measured loss when mated to an unknown connector. This is an important point often not fully explained.  In order to measure the loss of the connectors you must mate them to a similar, known good, connector. When a connector being tested is mated to several different connectors, it may have different losses, because those losses are dependent on the reference connector it is mated to."
The TIA spec of 0.75dB is for a mated pair of connectors. If you have been passing connectors tested @ 1.5dB may have some very bad connectors in your cabling!

Microscope Magnification (11/13)
I am doing a lot of fiber optic jumpers for control systems,  either single mode or multimode. I want to get a scope to inspect the ends after I clean them would you recommend a 200X,  400X handheld or one similar to a Noyes OFS 300 200C?
A: We prefer to use lower magnification and have a wider view so I can see more of the ferrule to determine its condition. You can see the fiber effectively at 100X but 200X may be better. 400X may be too much for most tasks like inspecting for cleanliness, but may be good if you are polishing SM for good reflectance. We've used the Westover units for years because they offer two different methods of illumination - direct and at an angle. If you are doing a lot of patchcords, I recommend a video microscope. I've used the Noyes unit that interfaces to a PC to create the FOA Microscope Inspection YouTube video here: and it works well.

Recycling Cabling
Who can I contact regarding recycling cable I am removing from a building?
A: Here are some people who say they recycle fiber optic cable or at least know how to do it:

Tech Hint: Did You Know You Have A Fiber Optic Tester In Your Pocket?
Yes! That old mobile phone has a camera which may be sensitive to infrared light - lots more than your eye - and can detect light in an optical fiber or from a transmitter.  Chris Hillyer,CFOT/CFOS/I, Master Instructor, Northern California Sound & Communication JATC sent us some photos showing how this works. See below or the video now on YouTube. Update: You should check out your old cell phones before you recycle them. We've found older models use sensors which are better at infrared than the newer ones which take better pictures. This is a good use for your old cell phones hiding in the drawer!

Fiber Cleaning
This is a topic we keep reminding everybody about, and here is why:
From a contrator in the Middle East: Here some samples of the connectors for SM fiber already installed in the system we were testing.
dirty connector   dirty connector
As you can see, the dirt is large compared to the size of the fiber (dark gray), and the core (not visible here) is only 9/125 of the overall diameter of the fiber!

Clean Every Connector - A Lesson We Learned From Creating Lessons
In creating the fiber characterization curriculum, we got inputs from many experienced techs about the testing requirements. Everyone we talked to made a big point about cleaning and inspecting connectors before testing. Dirty connectors are a major problem with errors in testing. We've also seen that many installers think that if a connector, especially new connectors, has a "dust cap" on the connector, it does not need cleaning. WRONG!

The common name for the plastic caps on connector ferrules is "dust cap" and a friend says they are called "dust caps" because they are full of dust. Those plastic caps are made by the millions, popped out of plastic molding machines into barrels and stored until put into plastic bags. Whenever you remove one of them, clean the connector before testing or connecting it.
More on connector cleaning is here and here

More on cleaningSee Product News below for links to vendors of fiber cleaning products.

What You Need To Know About Fiber Optic Cleaning And More
Ed Forrest, one of the industry experts on cleaning fiber optic connectors, retired about a year ago. We encouraged him to put down on paper what he knew about fiber cleaning and he took our advice. He's now created 4 books on cleaning topics that cover just about everything you need to know. And he added another volume that's also important - maintaining fusion splicers. We recommend these books highly.

How to Precision Clean All Fiber Optic Connections
Understanding Cross-Contamination Points on Fiber Optic Inspection & Test Equipment
Maintaining a Fiber Optic Fusion Splicer
Comparison Study of Precision Cleaning Methods for All Fiber Optic Connection

Whitepaper: The Significance to Optical Internconnect: Properly Cleaning a Fiber Optic Connection

Information on Ed's books is at

See news about Fiber Optic Cleaning Videos on YouTube by ITW Chemtronics below.

Fiber Optic Cleaning Videos on YouTube 

See news about Fiber Optic Cleaning Videos on YouTube by ITW Chemtronics three fiber optic cleaning videos on YouTUbe covering Dry CleaningWet-Dry Method, FiberWash and Combination Cleaning. They are good explanations of cleaning processes - the Wet-Dry is especially interesting.

Measurement Uncertainty: Everyone testing fiber optics should understand that every measurement has some uncertainty - whether you are measuring loss, length, wavelength, power, etc. Knowing that uncertainty is very important to interpreting the measurement. It's worthwhile to read and understand the issue of measurement accuracy covered in this page of the FOA Online Fiber Optic Reference Guide.


Worth Reading or Watching:

We are moving most of the articles in this section to the FOA's Pinterest Page "Worth Reading" - Go there for the latest links

Sign up at the FOA  Pinterest board Pinterest

FOA "Quickstart Guides"

In our continuing quest to help people understand how to test fiber optic cable plants and communications systems, we've created two more "QuickStart Guides to Fiber Optic Testing." They are simple, step-by-step guides on how to test fiber optic cable plants, patchcords or single cables using insertion loss or OTDR techniques and optical power from transceivers. It's as straightforward as it can get - what equipment do you need, what are the procedures for testing, options in implementing the test, measurement errors and documenting the results.
It can't get much simpler.
Send anybody you know who needs to know about fiber optic testing here to learn how it's done in a few minutes.

Testing Fiber Optic Cable Plants And Patchcords  

Testing Fiber Optic Cable Plants With An OTDR  

Measuring Optical Power In Communications Systems 

Like Crossword Puzzles? Here's Some On Fiber Optics

EP crossword

Do you like crossword puzzles? How about one on fiber optics - or maybe a half-dozen of them? FOA Master Instructor Eric Pearson of Pearson Technologies has created a series of crossword puzzles on fiber optics that are keyed to the FOA CFOT reference materials and his book Professional Fiber Optic Installation, v.9. You can have fun and study fiber optics at the same time!

This months crossword puzzle is on "Optoelectronics and Splicing" - Download the crossword puzzle on 
"Optoelectronics and Splicing."

If you missed the earlier puzzles, here they are:
Download the PDF file of the crossword on "Light and Fiber".
Download the PDF file of the crossword puzzle on "Cables".
Download the crossword on "Connectors & Splices."

Older Fiber, Do You Know How Good It Is?

There's millions of miles of long distance fiber installed around the world and most of it likely to see an upgrade of the systems operating on it, probably in the near future. Twenty years ago, most of it was probably running at ~1Gb/s, ten years ago it was probably 2.5 Gb/s, recently it was likely to be 10Gb/s but now many are being considered for 100Gb/s or beyond. Can the fiber support such speeds? Can it be "repaired" or "modified" to make it possible to use it at higher speeds? If you own that fiber, can you say what it is worth without knowing its future upgrade capability.

In order to know the potential for upgrades on your cable plant, you need to test it. This process involves a number of tests and is called "fiber characterization." Greg Stearns of TTP-US, an FOA Corporate Member, performs these tests and has written a short article on why you need to characterize fiber and how its done. Read about fiber characterization from someone who does it often and can explain it well.

Download the paper here (PDF, 80kB).

Demystifying Singlemode Fiber Types

Singlemode fiber has a lot of names and users are confused by the different names depending on the standards organization you refer to IEC, ITU or TIA designation. Most widely used are the ITU G65X designations but even there we find many designations. Shaun Trezise of M2FX has posted a simple explanation on the company blog that helps explain the different types and where they are used.  Read more on the M2FX blog 

There is a cross reference to the IEC, ITU and TIA designations on the FOA Guide.

EXFO Offers Super Posters And More


EXFO offers some super posters, guides and books. The FTTx and OTDR posters are really useful! Look at the whole selection here.

Getting Cables Out Of Conduit

Usually we are concerned about reducing friction when pulling cables through conduit, but sometimes you need to get them out. Here is a page from American Polywater the leading lubricant company with advice on the subject.

What Is The FOA?
Hear FOA President Jim Hayes tell the FOA Story in a 2-part interview by Sound & Video Contractor Contributing Editor Bennett Liles. It tells about the FOA history, goals and achievements.
Part 1:  
Part 2

What Happens To Old Fibers?
In a recent web search, we found this article from Corning, reprinted from a IWCS presentation in 1995. It discusses extensive tests on a 1984 cable installed in the northern US to see how it had degraded in almost 10 years. It is interesting to see how the fiber survived OSP exposure. Read it here.

Australia's Standard Is Comprehensive Guide To Customer Cabling (Get your copy free)
In answering a recent technical questino, Trevor Conquest in Australia pointed to the Australian Standard  "Installation Requirements For Customer Cabling." When we checked, it is on the web and can be downloaded. It's a big book - 220 pages - full of details for fiber and copper installations. We recommend you download yourself a copy - go here.

AU Std

Demystify fiber inspection probe technical specifications - From EXFO
The intent of this application note is to promote a better understanding of video inspection probe specifications and features. Properly understanding the key specifications and features will greatly facilitate the decision process involved in acquiring such devices. Understanding the key aspects of fiber inspection probes will also help users understand how fiber inspection probes operate, thus enabling them to maximize the full potential of these devices. Read more.

Where In The US Do Contractors Need Licenses For Fiber Optics?

We often get asked where in the US do contractors doing fiber optic installations need licenses. We found a good website for that information, the NECA -NEIS website. You might remember NECA-EIS, as they are the partner with the FOA in the NECA/FOA 301 Fiber Optic Installation Standard. NECA is the National Electrical Contractors Association and NEIS stands for National Electrical Installation Standards. They have a very easy to use map and table that gives you data on every state in the US, so mark these pages for future reference.

NECA/NEIS (See “State Regulations”) (all electrical licensing)
Low Voltage:

How Is Fiber Manufactured?

Manufacturing fiber at OFS

OFS invites you on a tour of their multimode fiber manufacturing facilities in this new 5-minute video. You will see their highly automated manufacturing operation in Sturbridge, Mass., including their patented MCVD preform fabrication process to fiber draw and final product testing. With a technological heritage dating back to AT&T and Bell Labs, OFS has been manufacturing high-quality multimode fiber since 1981.
Watch the video here.

Benchmarking Fusion Splicing And Selecting Singlemode Fiber
We've been asked many times "How long does it take to splice a cable?" It's not a simple answer as it varies with the number of fibers in the cable and the work setup, including whether one or two techs are working at a job site. FOA Master Instructor Joe Botha of Triple Play in South Africa did his own analysis based on decades of experience both splicing cables and teaching others how to do it properly. This is one of the best analyses we have seen because Joe includes prep times as well as splicing times and differentiates between one tech and two techs working together. He adds some other tips on fusion splicing too. This should be mandatory reading for every tech and given to every student! Here is Joe's splicing analysis. 

Joe also has an excellent writeup on how to choose singlemode fiber that helps understanding the different types of G.6xx fiber. Read it here.
And you will want to read Joe's report on splicing different types of SM fiber, including bend-insensitive (G.657) fiber. Read it here.

Free - Mike Holt's Explanation Of The US National Electrical Code (NEC) For Communications Cables
Mike Holt is the acknowledged expert of the US National Electrical Code (NEC). His books and seminars are highly praised for their ability to make a very complicated standard (that is in fact Code - law - in most areas of the US) easily understood. Part of the appeal is Mike's great drawings that make understanding so much easier. Mike makes Chapter 8 of his book available free. It covers communications cables, telephones, LANs, CATV and CCTV, for premises applications. Even if you live in a region or country where the NEC is not the law, you may find this interesting.
Download Mike's Chapter Here

Fiber Optic Cleaning Videos on YouTube
ITW Chemtronics has three fiber optic cleaning videos on videos covering Dry CleaningWet-Dry Method, FiberWash and Combination Cleaning. They are good explanations of cleaning processes - the Wet-Dry is especially interesting.
Download yourself a copy and read it

Good Technical Website For Installers
American Polywater ( has one of the best technical website for cable installers. Check out their website, especially “Videos,” “Engineer’s Corner” and  “Calculators.”

Fiber Optic Safety Poster
We've had numerous requests to reprint our guidelines on safety when working with fiber optics, so we have created a "Safety Poster" for you to print and post in your classroom, worksite, etc. We suggest giving a copy to every student and installer.


FOA Tech Topics - 

A Fiber Optic Tester In Your Pocket?  (See the video on Corning on YouTube )
Yes! The camera in your old cell phone is sensitive to infrared light - lots more than your eye - and can detect light in an optical fiber or from a transmitter.  Chris Hillyer,CFOT/CFOS/I, Master Instructor, Northern California Sound & Communication JATC brought this to our attention.
IR Viewer 850 nm  IR Viewer 1300 nm

If you have an old cell phone, try it. Our experience is that older cell phone cameras have better sensitivity at IR wavelengths than newer phones, so you may want to toss that old flip phone into the toolbox.


Product News

New Ripley Fiber Stripper

Ripley recently sent us some new fiber strippers to try, the Ripley Tri-hole fiber stripper model  CFS-3. It is aimed at contractors and installers and is very reasonable prived - plus we understand there are some introductory price specials from some distributors.

The CFS-3 can strip fiber jackets, 900 micron buffer and 250 micron buffer for one step cable preparation.
- 1st hole strips 1.6 – 3mm Fiber Jacket to the 600-900 buffer coating.
- 2nd hole strips the 600-900 micron buffer coating to the 250 micron coating.
- 3rd hole strips the 250 micron buffer coating to the 125 micron glass fiber.

fiber stripper

We tested the CFS-3 on several fibers and cables and found it easy to use and very consistent. It seemed much less sensitive to the angle you hold it at when stripping fibers than some strippers like this and it was very effective even stripping some older, more brittle fibers.

Here's more information on the Ripley CFS-3 Part #: 81300.

VIAVI Introduces OLTS For MPO Connectors

One of the biggest problems with multifiber MPO connectors is testing. Viavi Solutions (formerly JDSU) has introduced its SmartClass Fiber MPOLx optical loss test set, a basic test solution for cabling systems that utilize multi-fiber MPO connectors. The testing of parallel optics with MPO connectors has always been difficult for regular single or dual fiber OLTS, needing MPO to SC or LC breakout cables for testing one fiber at a time and using the three cable “0 dB” reference method. The MPOLx should make testing cable plants using these connectors much easier.

The MPOLx can test for length, optical loss, polarity and inspect fiber end-face condition - a complete cable plant test. The ability to check polarity is important since there are several polarity schemes used in MPO systems. The MPOLx is fast too, delivering comprehensive test results in less than 6 seconds for all 12 fibers.

More information on the Viavi MPOLx here.

YOKOGAWA OTDR Has Extended range, High Resolution And Multitasking

Yokogawa OTDR

One OTDR manufacturer you don't hear as much about is YOKOGAWA (formerly ANDO) which is too bad - they make some of the best OTDRs, exemplified by this new model AQ7280. Need long range - how about 50dB. High resolution - 0.6m dead zone. Like touch screens, but for some functions want hard buttons, it's got that. Options for VFL, microscope, light source and power meter, etc. - it has that too.
But the unique aspect of the YOKOGAWA AQ7280 is it offers multitasking - you can let do a trace with long averages while you inspect connectors, make power readings, use the VFL or other functions.
More info on the YOKOGAWA AQ7280.

FOA thanks Yokogawa for a gift of an OTDR to use for R&D and teaching!

Recycling Communications Cable

FOA was contacted by a company that recycles electronics communications equipment and cabling. CommuniCom recycles cable/metals/e-waste for Telcos and CATVs. They also recycle Fiber Optic Cable and associated Materials (the fiber scrap). And, they reclaim OSP abandoned copper cables (abandoned from road moves or FTTx growth). This is a huge part of our business. They do the work (permitting/locates/labor) for free and we revenue share back with our clients (telcos).

Contact Steve Maginnis
803.371.5436 (cell)

Micro-Trenching, Cable Removal
Nano-Trench offers products for micro (or I guess they call it nano-) trenching and their website is very informative. They also have Kabel-X, a method of extracting copper cables from old conduit. Both websites are informative and interesting. Watch this video on the cable removal process!

Protecting Pedestals From Rodents
Pedestals and underground vaults can be damaged by rodents who come up through the base and damage cables. Uraseal "Drain N'Seal" foam deters mice from taking up residence in your pedestals. They have some good videos on using their product.

Used Test Equipment – Buy or Sell

Have you read the FOA pages on cleaning?


FTTH Notes:

Want To Learn More About FTTx? Try our free online self-study program at Fiber U.

 Digging Safely (Read the FOA Tech Topic)

There is a toll-free "call before you dig" number in the USA: 811

See for more information

The Common Ground Alliance has an excellent "Best Practices Guide" online

National Fiber Optic Protection Summit by the "811" group.

The US Department of Transportation has a website called "National Pipeline Mapping System" that allows one to search for buried pipelines.   


Employment/Job Listings

Where Are The Jobs In Fiber Optics?

Fiber Optic Installation Banner

The FOA was chartered to "promote professionalism in fiber optics through education, certification and standards." Our focus on creating a professional workforce to properly design, install, maintain and repair communications network infrastructure has led us to work with groups in many different areas of technology that use fiber optics, way beyond the basic telecom applications that most of us think of first. FOA has probably worked with most of the potential applications of fiber optics, but we're always learning about new ones!
In addition, we get lots of calls and emails from our members looking for information about where the jobs are and how to train for them. FOA has created three ways to help you find jobs, train for them and apply for them.

Where Are The Jobs In Fiber Optics?
FOA has created a 20 minute YouTube video that talks about all the applications for fiber optics, what jobs are involved and the qualifications for the workers in the field. Besides telecom and the Internet, we cover wireless, cable TV, energy, LANs, security, etc. etc. etc. It's a quick way to get an overview of the fiber optic marketplace and we give you an idea of where the opportunities are today.

Watch the new FOA YouTube Video: Where Are The Jobs In Fiber Optics?

What Training Is Needed For The Jobs In Fiber Optics?
As you will learn from the video described above, the jobs in fiber optics are quite diverse. FOA has investigated these jobs to understand the needs of workers for those jobs and, when necessary, create curriculum and certifications to properly train workers. For example, the FOA FTTx certification was developed at the request of Verizon who needed specialized installers for their FiOS program. Now we are working with the industry on the OLAN (Optical LAN) program (see below).
We have summarized the jobs and required training in a new web page that has two uses - 1) If you have FOA certifications, what jobs are you specifically qualified for? - 2) If you are working in a specialized field or want to get a job in that area, what training and certifications will qualify you for those jobs?
What Training And Certifications Are Needed For Jobs In Fiber Optics? 

How To Find And Apply For Jobs In Fiber Optics
We get many questions from CFOTs, students at FOA-Approved schools and others contemplating getting into the fiber optic business regarding jobs in fiber optics - and how to find them - so we’ve created a new web page to share some information we've gathered about jobs in our industry. The information is designed to help you understand what jobs are available in fiber optics, how to find them and apply for them.
If you are looking for a job in fiber optics, here is the FOA's guide to jobs. 

We hope you find this useful. FOA tries to find new to increase the professionalism in our industry and helping qualified people find jobs is our highest priority - read the article below to see why! If you have feedback on how we can help you and our industry, contact us at

Join FOA on 
FOA on LinkedIn

A list of 10 ways to get your resume noticed, from Marketplace on NPR   

Electrical/Low Voltage Workers in Wisconsin
Casey Healey, Business Agent for IBEW Local 159 in McFarland,WI suggested a link to the Wisconsin Electrical Workers on the FOA jobs website. They have nine IBEW locals that cover the entire state of Wisconsin. All nine locals use this website in search of low voltage technicians that are certified in copper or fiber. After an individual fills out the employment opportunities form on the website a representative from that person's area would be in contact with them to discuss job opportunities within the IBEW as a low voltage apprentice, trainee or a technician. In Wisconsin they teach the 3 year NJATC Voice Data Video apprenticeship program. WI JATCs use the books that FOA has written for the NJATC in their curriculum

 Do listings in the FOA Newsletter and LinkedIn groups Work? Here's feedback:

"We did great!  We have over 15 interviews next week."

"Your newsletter generated a significant number of applicants and we have filled the position."



 FOA Logo Merchandise

New FOA Swag! Shirts, Caps, Stickers, Cups, etc.
FOA T Shirt
The FOA has created a store on offering lots of new logo merchandise. It has lots of versions of shirts and other merchandise with "FOA," "Fiber U," "Lennie Lightwave" designs and more so you should find something just for you! See FOA on Zazzle.

Your Name, CFOT® - It pays to advertise!

The FOA encourages CFOTs to use the logo on their business cards, letterhead, truck or van, etc. and provides logo files for that purpose. But we are also asked about how to use the CFOT or CFOS certifications. Easy, you can refer to yourself as "Your Name, CFOT" or "Your Name, CFOS/T" for example.

Feel free to use the logo and designations to promote your achievements and professionalism!

Contact FOA at to get logos in file format for your use.


Remember To Renew Your Certification !

Remember to renew your FOA certification. All current CFOTs have a ID Card with their certification data and we keep a database of current CFOTs to answer inquiries regarding your qualifications if needed.  If you forgot to renew, use the online application form to renew NOW!

You can now renew your FOA certification online - and get an extra month free. Details here.



To Contact The FOA:
The Fiber Optic Association Inc. (FOA) is the international professional society of fiber optics. FOA is chartered to promote fiber optics through education, certification and standards.

Privacy Policy: The FOA does not use cookies or any other web tricks to gather information on visitors to our website, nor do we allow commercial advertising. Our website hosts may gather traffic statistics for the visitors to our website and our online testing service, ClassMarker, maintains statistics of test results. We do not release or misuse any information on any of our members except we will confirm FOA certifications and Fiber U certificates of completion when requested by appropriate persons such as employers or personnel services.
Read the complete FOA Privacy Policy here.
Contact Us
The Fiber Optic Association or email <>

Time To Renew Your FOA Membership/CFOT?

To keep your FOA certifications and membership active, you need to renew every year (or two or three, longer times save you money.)
You can now renew with PayPal
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