For most of 2008, my monthly columns in Electrical Contractor have been about fiber optic network design. The goal is to educate you on the process of designing fiber optic networks, and now it’s time for a pop quiz. The correct answers and explanations are in red. Questions for this quiz are based on Jim Hayes’s columns on fiber optic design from April and May 2008.
1. Fiber optic network designers should have an in-depth knowledge of ________.
A. Fiber optic components and systems
B. Installation processes
C. All applicable standards, codes and any other local regulations
D. All of the above
Understanding all these is necessary for the designer to properly design a fiber optic network.
2. The first requirement that must be considered for a new fiber optic project is ________.
A. The customer’s communications system requirements
B. Where the cable plant
will be run
C. Whether it will be multimode or single-mode fiber
D. The customer’s budget
Everything in the network design depends on the customer’s communications needs.
3. Fiber is the communications medium of choice for practically everything but ________.
A. Cell phone network backbones
B. Intelligent highway systems
C. CATV backbones
D. Premises cabling to the desktop
Premises cabling to the desktop still uses copper since every PC comes with a free copper port.
4. Outside plant systems generally use single-mode fiber to support higher speed systems over longer distances, while shorter premises systems use multimode fiber.
Most outside plant links are too long for multimode fiber with it’s higher loss and lower bandwidth. However it works well in shorter premises applications even at speeds up to 10 gigabits per second.
5. Multimode fiber optic systems are lower priced than single-mode
systems because ________.
A. Multimode fiber is cheaper
B. Multimode cable is cheaper
C. Multimode electronics are cheaper
D. All of the above
Multimode electronics use inexpensive LEDs or VCSEL lasers that are much cheaper than the expensive lasers needed with singlemode fibers.
6. Practically every cable in a telephone system is fiber except ________, and even they are being rebuilt with fiber.
A. Long-distance links
B. Undersea links
C. Metropolitan links
D. Connections to the home
Fiber is used exclusively in every telecom link except the home, where it is now making big inroads with systems like Verizon’s FiOS.
7. Copper cabling to the desktop in offices is being replaced by ________.
A. Wi-Fi links
B. Bluetooth links
C. Multimode OM3 fiber
D. Single-mode fiber
Users desires for “mobility” and the higher bandwidth of new WiFi systems means that most users do not need cable connections at the desktop.
8. A fiber-to-the-desktop system in an office can be cost effective if designed properly since it ________.
A. Provides higher bandwidth needed for today’s faster PCs
B. Does not need costly telecom rooms with switches, uninterruptible power and grounds
C. Costs much less to install than Cat 6
D. Does not require special electronics
Centralized fiber systems only need electronics at the ends, not in telecom closets in the middle of the link to the user.
9. Connecting two buildings across
a highway or waterway may be
more easily done with line-of-sight wireless systems using either optical or radio transmission.
Line of sight systems using radio waves or optical laser transmission are good choices when buildings are separated by roads or waterways that would require expensive construction.
10. The fiber optic network designer must be familiar with ________.
A. Electrical power systems
B. Uninterruptible power
C. Grounding electronic circuits
D. All of the above
Electrical power, properly conditioned and uninterruptable and a data ground are essential to the proper operation of any communications system.
HAYES is a VDV writer and trainer and the president of The Fiber Optic Association. Find him at www.JimHayes.com.