Chapter 25: Fiber-Optic Systems
TRUE/FALSE
1. Most new telephone trunk cables are fiber-optic.
ANS: T
2. Cable TV systems use fiber-optic cable.
ANS: T
3. Many data network cables are fiber-optic.
ANS: T
4. Fiber-optic cable is not practical for telephone trunk cables.
ANS: F
5. CATV uses analog modulation on fiber-optic cables.
ANS: T
6. Usually, splicing losses can be disregarded in loss-budget calculations.
ANS: F
7. The rise time of a transmitter limits its bandwidth.
ANS: T
8. RZ encoding allows twice as much pulse spreading as NRZ.
ANS: F
9. The product of bandwidth times distance describes dispersion in a multimode fiber-optic cable.
ANS: T
10. Regenerative repeaters for fiber-optic cables typically convert the light signal to an electrical signal, and then back to light.
ANS: T
11. Optical amplifiers are not suitable for digital signals.
ANS: F
12. Dispersion effects accumulate when optical amplifiers are used.
ANS: T
13. Most fiber-optic systems use TDM.
ANS: T
14. Fiber-optic cables shorter than 100 km typically do not require repeaters.
ANS: T
15. SONET operates at a base speed of 25 Mbps.
ANS: F
16. SONET solves many of the timing problems in synchronizing digital signals.
ANS: T
17. SONET is typically used on LANs.
ANS: F
18. FDDI can be used on a LAN.
ANS: T
19. Soliton pulses can travel down a fiber-optic cable with no dispersion.
ANS: T
20. TDR cannot be used on fiber-optic cables.
ANS: F
MULTIPLE CHOICE
1. FDDI stands for:
a. | Fiber Digital Data Interface | c. | Fiber Distribution Delay Interface |
b. | Fiber Distributed Data Interface | d. | Frequency-Division Data Interface |
ANS: B
2. FITL stands for:
a. | Fiber In The Loop | c. | Frequency Input to The Loop |
b. | Fiber Input Timing Loss | d. | Fiber Input Timing Loop |
ANS: A
3. FTTC stands for:
a. | Fiber Transmission Timing Constraint |
b. | Fiber Transmission Technology Committee |
c. | Fiber Telephone Transmission Cable |
d. | Fiber To The Curb |
ANS: D
4. SONET stands for:
a. | Simple Optical Network | c. | Synchronous Optical Network |
b. | Standard Optical Network | d. | none of the above |
ANS: C
5. DWDM stands for:
a. | Digital Wavelength-Division Modulation |
b. | Dense Wavelength-Division Modulation |
c. | Double Wavelength-Division Modulation |
d. | Dense Wavelength-Division Multiplexing |
ANS: D
6. A Soliton is a:
a. | defect in the glass | c. | type of pulse |
b. | type of particle | d. | type of optical network |
ANS: C
7. Adding bits to synchronize one digital signal to another is called:
a. | bit stuffing | c. | SDH |
b. | bit-synch | d. | WDM |
ANS: A
8. Power above the minimum required by an optical receiver is called:
a. | gain margin | c. | excess gain |
b. | system margin | d. | overdrive |
ANS: B
9. Typically, repeaters are not required for fiber-optic cable lengths up to:
a. | 1000 miles | c. | 100 km |
b. | 100 miles | d. | 10 km |
ANS: C
10. In SONET, OC-1 stands for:
a. | Optical Carrier level one | c. | Optical Channel one |
b. | Optical Coupler unidirectional | d. | Optical Cable type 1 |
ANS: A
11. In SONET, STS stands for:
a. | Synchronous Transport Signal | c. | Synchronous Transmission Signal |
b. | Synchronous Transport System | d. | Synchronous Transmission System |
ANS: A
12. A commonly used fiber-based system for LANs is:
a. | FDDI | c. | gigabit Ethernet |
b. | high-speed Ethernet | d. | all of the above |
ANS: D
13. The use of solitons on fiber-optic cables is:
a. | common | c. | obsolete |
b. | experimental | d. | not possible |
ANS: B
14. OTDR stands for:
a. | Optical Time-Delay Response | c. | Optical Time-Domain Reflectometer |
b. | Optical Timing Delay Requirement | d. | Optical Time-Division Relay |
ANS: C
15. Using fiber-optic cable in a telephone system except for the connection to the subscriber's phone is called:
a. | FDDI | c. | FITL |
b. | FTTC | d. | SONET |
ANS: B
COMPLETION
1. FTTC stands for Fiber To The ____________________.
ANS: Curb
2. FITL stands for Fiber In The ____________________.
ANS: Loop
3. SDH stands for Synchronous Data ____________________.
ANS: Hierarchy
4. WDM stands for ____________________-division multiplexing.
ANS: Wavelength
5. SONET stands for ____________________ Optical Network.
ANS: Synchronous
6. FDDI stands for Fiber ____________________ Data Interface.
ANS: Distributed
7. Optical amplifiers use ____________________-doped glass.
ANS: erbium
8. Optical amplifiers use a ____________________ laser.
ANS: pump
9. Dense ____________________ allows many different wavelengths of light to share a cable.
ANS: WDM
10. The OC-1 line rate is ____________________ Mbps.
ANS: 51.84
11. SONET does not use bit ____________________ to synchronize two digital signals.
ANS: stuffing
12. SONET uses a ____________________ to denote the starting position of an information frame.
ANS: pointer
13. FDDI systems use two ____________________ rings to carry signals.
ANS: token
14. The two rings of an FDDI system carry data in ____________________ directions.
ANS: opposite
15. Each ____________________ in an FDDI system acts as a regenerative repeater.
ANS: node
16. FDDI uses ____________________ mode cables.
ANS: multi
17. The data rate of an FDDI system is ____________________ bps.
ANS: 100 M
18. SONET frames have considerably more ____________________ than do DS frames for information about signal routing and setup.
ANS: overhead
19. The number of bytes in a SONET frame is ____________________.
ANS: 810
20. The number of bytes in the payload of a SONET frame is ____________________.
ANS: 774
21. The number of rows in a SONET frame is ____________________.
ANS: 9
22. The total number of overhead bytes in a SONET frame row is ____________________.
ANS: 4
23. The number of path overhead bytes in a SONET frame row is ____________________.
ANS: 1
24. SONET frame rows contain path overhead and ____________________ overhead.
ANS: transport
25. In SONET, SPE stands for synchronous payload ____________________.
ANS: envelope
SHORT ANSWER
1. What is the bandwidth of a first-order LPF with a rise time of 350 nanoseconds?
ANS:
1 MHz
2. Calculate the total rise time for a fiber-optic system if the transmitter, receiver, and cable each have a rise time of 50 nanoseconds.
ANS:
86.6 nanoseconds
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