This is the Multiple Choice Questions in Chapter 8: The Telephone System from the book Electronic Communication Systems by Roy Blake
See also: MCQ in Electronic Communication Systems by George Kennedy
Start Practice Exam Test Questions
Choose the letter of the best answer in each questions.
MULTIPLE CHOICE
1. DTMF stands for:
a. Digital Telephony Multiple Frequency
b. Dial Tone Master Frequency
c. Dual-Tone Multifrequency
d. Digital Trunk Master Frequency
Answer: Option C
Solution:
2. PSTN stands for:
a. Public Switched Telephone Network
b. Private Switched Telephone Network
c. Primary Service Telephone Network
d. Primary Service Telephone Numbers
Answer: Option A
Solution:
3. POTS stands for:
a. Private Office Telephone System
b. Primary Office Telephone Service
c. Primary Operational Test System
d. Plain Old Telephone Service
Answer: Option D
Solution:
4. LATA stands for:
a. Local Access and Transport Area
b. Local Access Telephone Area
c. Local Area Telephone Access
d. Local Area Transport Access
Answer: Option A
Solution:
5. A LATA is a:
a. a local calling area
b. a type of digital local network
c. a way of accessing a tandem office
d. a way of accessing a central office
Answer: Option A
Solution:
6. Central offices are connected by:
a. local loops
b. trunk lines
c. both a and b
d. none of the above
Answer: Option B
Solution:
7. Local loops terminate at:
a. a tandem office
b. a toll station
c. a central office
d. an interexchange office
Answer: Option C
Solution:
8. Call blocking:
a. cannot occur in the public telephone network
b. occurs on the local loop when there is an electrical power failure
c. occurs only on long-distance cables
d. occurs when the central office capacity is exceeded
Answer: Option D
Solution:
9. In telephony, POP stands for:
a. Post Office Protocol
b. Point Of Presence
c. Power-On Protocol
d. none of the above
Answer: Option B
Solution:
10. The cable used for local loops is mainly:
a. twisted-pair copper wire
b. shielded twisted-pair copper wire
c. coaxial cable
d. fiber-optic
Answer: Option A
Solution:
11. FITL stands for:
a. Framing Information for Toll Loops
b. Fiber In the Toll Loop
c. Framing In The Loop
d. Fiber-In-The-Loop
Answer: Option D
Solution:
12. Loading coils were used to:
a. increase the speed of the local loop for digital data
b. reduce the attenuation of voice signals
c. reduce crosstalk
d. provide C-type conditioning to a local loop
Answer: Option B
Solution:
13. DC current flows through a telephone:
a. when it is on hook
b. when it is off hook
c. as long as it is attached to a local loop
d. only when it is ringing
Answer: Option B
Solution:
14. The range of DC current that flows through a telephone is:
a. 20 µA to 80 µA
b. 200 µA to 800 µA
c. 2 mA to 8 mA
d. 20 mA to 80 mA
Answer: Option D
Solution:
15. The separation of control functions from signal switching is known as:
a. step-by-step switching control
b. crossbar control
c. common control
d. ESS
Answer: Option C
Solution:
16. The typical voltage across a telephone when on-hook is:
a. 48 volts DC
b. 48 volts, 20 hertz AC
c. 90 volts DC
d. 90 volts, 20 hertz AC
Answer: Option A
Solution:
17. The typical voltage needed to “ring” a telephone is:
a. 48 volts DC
b. 48 volts, 20 hertz AC
c. 90 volts DC
d. 90 volts, 20 hertz AC
Answer: Option D
Solution:
18. The bandwidth of voice-grade signals on a telephone system is restricted in order to:
a. allow lines to be “conditioned”
b. prevent “singing”
c. allow signals to be multiplexed
d. all of the above
Answer: Option C
Solution:
19. VNL stands for:
a. voltage net loss
b. volume net loss
c. via net loss
d. voice noise level
Answer: Option C
Solution:
20. Signal loss is designed into a telephone system to:
a. eliminate reflections
b. prevent oscillation
c. improve signal-to-noise ratio
d. reduce power consumption
Answer: Option B
Solution:
21. The reference noise level for telephony is:
a. 1 mW
b. 0 dBm
c. 1 pW
d. 0 dBr
Answer: Option C
Solution:
22. The number of voice channels in a basic FDM group is:
a. 6
b. 12
c. 24
d. 60
Answer: Option B
Solution:
23. Basic FDM groups can be combined into:
a. supergroups
b. mastergroups
c. jumbogroups
d. all of the above
Answer: Option D
Solution:
24. In telephone system FDM, voice is put on a carrier using:
a. SSB
b. DSBSC
c. PDM
d. PCM
Answer: Option A
Solution:
25. PABX stands for:
a. Power Amplification Before Transmission
b. Private Automatic Branch Exchange
c. Public Automated Branch Exchange
d. Public Access Branch Exchange
Answer: Option B
Solution:
26. SLIC stands for:
a. Single-Line Interface Circuit
b. Standard Line Interface Card
c. Subscriber Line Interface Card
d. Standard Local Interface Circuit
Answer: Option C
Solution:
27. In DS-1, bits are “robbed” in order to:
a. provide synchronization
b. carry signaling
c. cancel echoes
d. check for errors
Answer: Option B
Solution:
28. “Bit-stuffing” is more formally called:
a. compensation
b. rectification
c. justification
d. frame alignment
Answer: Option C
Solution:
29. ISDN stands for:
a. Integrated Services Digital Network
b. Information Services Digital Network
c. Integrated Services Data Network
d. Information Systems Digital Network
Answer: Option A
Solution:
30. Basic ISDN has not been widely adopted because:
a. it took to long to develop
b. it is too slow
c. it has been surpassed by newer technologies
d. all of the above
Answer: Option D
Solution:
31. ADSL stands for:
a. All-Digital Subscriber Line
b. Asymmetrical Digital Subscriber Line
c. Allocated Digital Service Line
d. Access to Data Services Line
Answer: Option B
Solution:
32. Compared to ISDN, internet access using ADSL is typically:
a. much faster
b. about the same speed
c. much more expensive
d. none of the above
Answer: Option A
Solution:
COMPLETION
1. A ____________________ is a local calling area.
Answer: LATA
Solution:
2. Central offices are connected together by ____________________ lines.
Answer: trunk
Solution:
3. One central office can be connected to another through a ____________________ office.
Answer: tandem
Solution:
4. With 7-digit phone numbers, ____________________ thousand telephones can connect to a central office.
Answer: ten
Solution:
5. Call ____________________ is when it becomes impossible for a subscriber to place a call due to an overload of lines being used.
Answer: blocking
Solution:
6. New ____________________ switching equipment uses TDM to combine signals.
Answer: digital
Solution:
7. Most local loops still use ____________________ copper wire.
Answer: twisted-pair
Solution:
8. As compared to a hierarchical network, a ____________________ network never needs more than one intermediate switch.
Answer: flat
Solution:
9. ____________________ coils were used to reduce the attenuation of voice frequencies.
Answer: Loading
Solution:
10. In a twisted-pair telephone cable, the red wire is called ____________________.
Answer: ring
Solution:
11. In a twisted-pair telephone cable, the green wire is called ____________________.
Answer: tip
Solution:
12. Of the red and green ‘phone wires, the ____________________ wire is positive with respect to the other.
Answer: green
Solution:
13. A telephone is said to have ____________________ the line when the central office sends it dial tone.
Answer: seized
Solution:
14. The ____________________ functions are provided by a SLIC.
Answer: BORSCHT
Solution:
15. A ____________________ coil prevents loss of signal energy within a telephone while allowing full-duplex operation over a single pair of wires.
Answer: hybrid
Solution:
16. In a crosspoint switch, not all ____________________ can be in use at the same time.
Answer: lines
Solution:
17. The old carbon transmitters generated a relatively ____________________ signal voltage.
Answer: large
Solution:
18. The generic term for Touch-Tone® signaling is ____________________.
Answer: DTMF
Solution:
19. A ____________________ line provides more bandwidth than a standard line.
Answer: conditioned
Solution:
20. In the telephone system, amplifiers are called ____________________.
Answer: repeaters
Solution:
21. An echo ____________________ converts a long-distance line from full-duplex to half-duplex operation.
Answer: suppresor
Solution:
22. ____________________ weighting is an attempt to adjust the noise or signal level to the response of a typical telephone receiver.
Answer: C-message
Solution:
23. In FDM telephony, the modulation is usually ____________________.
Answer: SSB / SSBSC
Solution:
24. In FDM telephony, ____________________ bands separate the channels in a group.
Answer: guard
Solution:
25. Because of “bit robbing”, a channel in a DS-1 frame allows only ____________________ kbps when used to send digital data.
Answer: 56
Solution:
26. A ____________________ is a group of 12 DS-1 frames with signaling information in the sixth and twelfth frames.
Answer: superframe
Solution:
27. In DS-1C, ____________________ bits are used to compensate for differences between clock rates.
Answer: stuff
Solution:
28. Busy and dial tone are referred to as ____________________ signals because they use the same pair of wires as the voice signal.
Answer: in-channel
Solution:
29. SS7 is the current version of _________________________ signaling.
Answer: common-channel
Solution:
30. SS7 is a ____________________-switched data network.
Answer: packet
Solution:
31. In ISDN, the ____________________ channel is used for common-channel signaling.
Answer: D
Solution:
32. In ISDN, the ____________________ channels are used for voice or data.
Answer: B
Solution:
33. Terminal equipment especially designed for ISDN is designated ____________________ equipment.
Answer: TE1
Solution:
34. The A in ADSL stands for ____________________.
Answer: asymmetrical
Solution:
35. In ADSL, the speed from the network to the subscriber is ____________________ than the speed in the opposite direction.
Answer: greater / faster
Solution:
SHORT ANSWER
1. For a certain telephone, the DC loop voltage is 48 V on hook and 8 V off hook. If the loop current is 40 mA, what is the DC resistance of the local loop?
Answer: 1000 ohms
Solution:
2. For a certain telephone, the DC loop voltage is 48 V on hook and 8 V off hook. If the loop current is 40 mA, what is the DC resistance of the telephone?
Answer: 200 ohms
Solution:
3. Which two DTMF tones correspond to the digit “1”? (Use the table in the text.)
Answer: 697 Hz and 1209 Hz
Solution:
4. Calculate the dB of VNL required for a channel with a 3 ms delay.
Answer: 1 dB
Solution:
5. If a telephone voice signal has a level of 0 dBm, what is its level in dBrn?
Answer: 90 dBrn
Solution:
6. A telephone test-tone has a level of 80 dBrn at a point where the level is +5dB TLP. If C-weighting produces a 10-dB loss, what would the signal level be in dBrnc0?
Answer: 65 dBrnc TLP
Solution:
Complete List of MCQ in Electronic Communication Systems by Blake
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