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17 Cards in this Set
- Front
- Back
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1. Cables tested with an OTDR do not require insertion loss testing with a light source and power meter or OLTS.
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FALSE
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. |
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2. Connectors at each end of the cable plant should not be counted when calculating the cable plant loss.
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FALSE
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. |
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3. The OTDR should never be used without a "launch cable" which is also called a "pulse suppressor."
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TRUE
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. |
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4. Cable plant loss should be estimated during the __________ phase.
A. Design B. Installation C. Testing D. Troubleshooting |
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. |
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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 |
D
OFSTP-7 is the US standard. There are several relevant international standards, including IEC 61280. |
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6. What test instrument(s) are used for insertion loss testing?
A. OLTS or light source and power meter B. VFL C. OTDR |
A
Testing insertion loss with a light source and power meter mimics actual cable plant use. |
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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 |
D
These are similar to the sources used in actual system operation. |
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8. What type of source is generally used for testing multimode fibers?
A. LED B. VCSEL C. Laser |
A
MM fibers are generally tested with LED sources and some kind of mode conditioning. |
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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 |
C
Three methods are specified so various connector types can be accommodated. |
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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 |
A
Testing patchcords using the single-ended method allows testing each connector separately. |
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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 |
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. |
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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 |
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. |
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13. The principle of operation of OTDRs is similar to __________ .
A. Power meters and sources B. Radar C. Mirrors D. Lenses |
B
OTDRs work like RADAR, sending out a test pulse and analyzing the return signals. |
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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 |
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. |
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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 |
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. |
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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 |
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. |
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17. OTDRs are used in outside plant cables to __________. (Select all that apply)
A. Verify splice loss B. Measure length C. Find faults D. Measure optical power |
A, B, C
OTDRs can do all these except directly measure optical power. |
