Tutorial Opening- Why Use Optical Fibers for Communications?



The Great Race

There is a race to install fiber optic technology to every home and business as practical, replacing copper wire technology that satisfied our needs for over a century.  But why the rush to replace copper wires with fiber strands?  What makes fiber technology so desirable?


Just two small glass strands about the size of your hair.... .......Can replace over 30 of these cables


Is Copper Doomed?

Copper wiring has two attributes that will doom the technology for future generations: limited bandwidth and susceptibility to noise.  Bandwidth is the capacity offered by the wires when carrying voice, video and data signals.  Copper wire technology was developed in an era where nearly 100% of the transmitted signals were voice telephone calls.  However, over the past 25 years most signals transmitted over telephone and cable TV lines are non-voice such as video and data, email, Internet sessions, text messages, tweets, etc.  Some of these signals require a higher bandwidth "pipe" to our homes and businesses than can be offered by copper wiring.  In terms of the capacity of each media, think of copper cables as installing a soda straw to our homes, whereas fiber optic technology is a fire hose.


Effective Capacity offered by Copper and Fiber "Pipes"


Additionally, copper wiring can be adversely affected by the electric power lines and other noise sources like lightning, causing data errors and noisy voice connections.  Over many years, copper cables tend to deteriorate and become trouble-prone requiring frequent repairs.



However, fiber optic technology is not affected by lightning or noise from electric power lines, offering a "clean" signal with very high bandwidth.  A fiber optic link can carry signals thousands of times larger than a copper cable over greater distances.  Copper cables can carry video and hi-speed data signals, but only for short distances.  Therefore, some companies have chosen to install fiber optic links "almost" all the way to a home or business, using the existing copper lines for a very short distance (usually less than 2,000 feet).  This is called "Fiber to the Neighborhood Node" (FTTN) or "Fiber to the Curb", whereas fiber installed all the way to your home is called "Fiber to the Home" (FTTH) or Fiber to the Building (FTTB).

Once the carrier installs a fiber node within 2,000 feet of the home/business, a copper-based, broadband solution called Digital Subscriber Line (DSL) is delivered to the customer over the short copper loop. DSL has enjoyed many "flavors" over the years such as Asymmetrical Digital Subscriber Line (ADSL), ADSL2+, Integrated Services Digital Network Digital Subscriber Line (IDSL), High Bit-Rate Digital Subscriber Line (HDSL), HDSL2, HDSL2+, HDSL4, Very High Bit-Rate Digital Subscriber Line (VDSL, best for delivering video content), VDSL2+ and Bonded DSL.  Each DSL flavor provided specific ranges of bandwidth and caveats, some with speeds approaching those available on fiber.


Fiber to the Node vs Fiber to the Home



Decision Time

Consider this: two fibers about the size of your hair can carry 32,256 voice calls, equivalent to 11 copper cables, each the size of Hulk Hogan's forearm.  The combined weight of just one foot of each of the 11 cables would be 220 pounds, yet the two fibers weigh less than one ounce.  If a backhoe severed the 11 copper cables, it would take a team of 22 technicians over three days non-stop to resplice all the lines, yet if two fibers were cut, a single technician would have service restored in less than one hour.


Let's recap the differences:

Copper Wiring for 32,256 Circuits: Optical Fibers for 32,256 Circuits:
11 cables (3,000 pairs of wires in each cable) 1 cable (2 fibers)
Total weight of 1 foot of all 11 cables: 220 pounds Total weight of 1 foot of both fibers: < 1 ounce
Space requirement for 11 cables: 20 inches diameter Space requirement for 1 cable: < 1 inch diameter
Restoral requirement if severed: 22 technicians x 3 days Restoral requirement if severed: 1 technician < 1 hour
Degraded in noisy environments Not affected by noisy environments
Designed for Voice, but Video and Data are distance-limited Carries Voice, Video and Data over great distances
Cable cost alone is over $100 per foot Cable cost alone is $5.00 per foot
Price to bury in ground 3 times (or more) than cost for fiber Price to bury in ground is 70% lower than equiv. copper

Given the factors above, which would you choose: Copper or Fiber?


A 32,256 Call Party Line!

During a cellular or traditional phone call your voice is mixed in with 32,255 other conversations, and then transported around the world at the speed of light through optical fibers that are about the size of a human hair. However, since your voices don't actually use the fiber at exactly the same moment in time, you never hear the other 32,255 callers. But how is this possible?

Suppose you mark a large X on the ground at the foot of Mount Rushmore, allowing 32,256 people to line up and take turns standing on the X to view a bird as it glides slowly across the face of the mountain. Your only rule is that, since only one person at a time can occupy the space over the X, they must move quickly enough so that each of the 32,256 people can view the mountain 8,000 times every second so as they scroll through the line, they never miss a foot of the birds flight. Sounds impossible, doesn't it? Yet that's exactly how your voice gets transmitted over the optical fiber! In fact, newer transmission methods have bumped that number to 129,024 simultaneous calls in a fiber optic system; every second of every day. That would be like building a four-story deck at Mount Rushmore, allowing four lines of 32,256 people to each pass 8,000 times per second!

Since the early years of presenting this material, the number of calls supported over an optical fiber transmission link have continued to increase exponentially.  Modern optical transmission systems now boast the capability to transmit over 1 million calls simultaneously.  In Lesson 5- Bumper Cars-How Pulses of Light Race to the Finish Line, we will reveal how your voice gets inserted into this raging river of light pulses without bumping into others.


Our FREE Fiber.Guru Telecommunications Technology Tutorial will discuss how optical fibers are manufactured and employed for worldwide communications of voice, video and data connections; how your voice is able to mix in the fiber with many others, yet not interfere with them; replay an actual event recorded where two optical fiber ends are joined by fusion splicing; reveal how to obtain a sample strand of optical fiber just like telephone and cable companies use in modern networks.

These and more questions answered in this tutorial, including experiments that can be performed with household items to help students grasp complex issues.   

Best of all, this tutorial is FREE and appropriate (safe) for all ages!  Click HERE and let's get started!


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