FOA Reference Guide To Outside Plant Fiber Optics
And Study Guide To FOA Certification
Answers To Chapter Questions
Chapter 8 Quiz - OSP Fiber Optic Testing
True/False
Indicate whether the statement is true or false.
1. Cables tested with an OTDR do not require insertion loss testing with a light source and power meter or OLTS.
ANSWER: F
OTDR
testing uses an indirect method that may not accurately predict the
loss of the cable plant with an actual transmission system so most
systems must be tested with a light source and power meter.
2. Connectors at each end of the cable plant should not be counted when calculating the cable plant loss.
ANSWER: F
It's
very important to include connectors at each end of the cable plant as
they will be included when the fibers in the cable plant are tested
with a light source and power meter.
3. The OTDR should never be used without a "launch cable" which is also called a "pulse suppressor."
ANSWER: T
Without
a launch cable, the OTDR cannot see the beginning of the cable under
test since the test pulse overloads the OTDR making it impossible to
see anything near the OTDR (dead zone) nor can it see the first
connector on the fiber.
Multiple Choice
Identify the choice that best completes the statement or answers the question.
4. Cable plant loss should be estimated during the __________ phase.
A. Design
B. Installation
C. Testing
D. Troubleshooting
ANSWER: A
When
the cable plant is designed, a loss budget which will be an estimate of
the loss of the entire cable plant must be done. That loss budget will
be used to determine if the cable plant will work with the system it is
designed for, provide estimates to compare test results to determine if
it has been installed properly and for troubleshooting at a later date.
If the loss budget was not done at the design stage, it must be done before testing for acceptance.
5. The US standard method of testing installed singlemode cables in a cable plant is described in __________.
A. FOTP-34
B. ISO 11801
C. FOTP-57
D. OFSTP-7
ANSWER: D
OFSTP-7 is the US standard. There are several relevant international standards, including IEC 61280.
6. What test instrument(s) are used for insertion loss testing?
A. OLTS or light source and power meter
B. VFL
C. OTDR
ANSWER: A
Testing insertion loss with a light source and power meter mimics actual cable plant use.
7.Singlemode fiber optic cables are tested with __________ sources at __________ and __________ wavelengths.
A. LED, 650, 850 nm
B. LED, 850, 1300 nm
C. Laser, 980, 1400 nm
D. Laser, 1310, 1550 nm
ANSWER: D
These are similar to the sources used in actual system operation.
8. What type of source is generally used for testing multimode fibers?
A. LED
B. VCSEL
C. Laser
ANSWER: A
MM fibers are generally tested with LED sources and some kind of mode conditioning.
9. How many methods are included in standards for setting the ‘0 dB‘ reference for loss testing?
A. One
B. Two
C. Three
D. Four
ANSWER: C
Three methods are specified so various connector types can be accommodated.
10. Patchcords can be tested to verify the connectors on each end individually by _________________?
A. Single-ended testing
B. Double-ended testing
C. OTDRs
D. Visual fault locators
ANSWER: A
Testing patchcords using the single-ended method allows testing each connector separately.
11. Reference cables must match the __________ of the cables being tested.
A. Fiber size and type
B. Fiber size and connector type
C.Connector type
D. Fiber size and loss specification
ANSWER: B
The
reference cables must have the same fiber as the cable being tested
and, of course, need connectors that can be mated to the cable under
test.
12. The total loss of the fiber in the cable plant
is calculated by multiplying the attenuation coefficient of the fiber
by the __________.
A. Length
B. Number of links
C. Number of connectors
D. Number of splices
ANSWER: A
The
attenuation coefficient of the fiber (often called just attenuation) is
in dB/km, so the loss of a length of fiber is calculated by multiplying
the attenuation coefficient by the length of the fiber in km.
13. The principle of operation of OTDRs is similar to __________ .
A. Power meters and sources
B. Radar
C. Mirrors
D. Lenses
ANSWER: B
OTDRs work like RADAR, sending out a test pulse and analyzing the return signals.
14. In long distance applications, OTDR distance measurement accuracy is limited by their __________.
A. Output power
B. Distance capability
C. Calibration of fiber index of refraction
D. Software
ANSWER: C
The
OTDR calculates distance using the index of refraction - a measure of
the speed of light in the fiber - and the length of time it takes the
pulse to go out and return.
15. Chromatic dispersion can be tested using an OTDR because __________.
A. An OTDR can measure the round trip time differences at each wavelength
B. Chromatic dispersion affects backscatter
C. The OTDR receiver is sensitive to the wavelength of light
D. OTDRs test at multiple wavelengths
ANSWER: A
Chromatic
dispersion means light travels at different speeds according to its
wavelength. Since the OTDR can test at different wavelengths, it can
measure CD.
16. In long distance applications intended for
wavelength division multiplexing, a ______ test is used to verify fiber
performance over all wavelengths.
A. Dispersion
B. Spectral attenuation
C. OTDR
D. VFL
ANSWER: B
In
a WDM system, especially CWDM with its wide spectral range that
includes the water peak, it's important to characterize the attenuation
of the fiber over the whole range.
Multiple Response
Identify one or more choices that best complete the statement or answer the question.
17. OTDRs are used in outside plant cables to __________.
A. Verify splice loss
B. Measure length
C. Find faults
D. Measure optical power
ANSWER: A,B,C
OTDRs can do all these except directly measure optical power..
Next: Lesson 9: Fiber Optic Network Design
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