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Blake: MCQ in The Telephone System

Blake: MCQ in The Telephone System

This is the Multiple Choice Questions in Chapter 8: The Telephone System from the book Electronic Communication Systems by Roy BlakeBlake: MCQ in The Telephone System. If you are looking for a reviewer in Communications Engineering this will definitely help. I can assure you that this will be a great help in reviewing the book in preparation for your Board Exam. Make sure to familiarize each and every questions to increase the chance of passing the ECE Board Exam.

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

View Answer:

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

View Answer:

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

View Answer:

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

View Answer:

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

View Answer:

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

View Answer:

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

View Answer:

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

View Answer:

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

View Answer:

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

View Answer:

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

View Answer:

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

View Answer:

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

View Answer:

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

View Answer:

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

View Answer:

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

View Answer:

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

View Answer:

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

View Answer:

Answer: Option C

Solution:

19. VNL stands for:

a. voltage net loss

b. volume net loss

c. via net loss

d. voice noise level

View Answer:

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

View Answer:

Answer: Option B

Solution:

21. The reference noise level for telephony is:

a. 1 mW

b. 0 dBm

c. 1 pW

d. 0 dBr

View Answer:

Answer: Option C

Solution:

22. The number of voice channels in a basic FDM group is:

a. 6

b. 12

c. 24

d. 60

View Answer:

Answer: Option B

Solution:

23. Basic FDM groups can be combined into:

a. supergroups

b. mastergroups

c. jumbogroups

d. all of the above

View Answer:

Answer: Option D

Solution:

24. In telephone system FDM, voice is put on a carrier using:

a. SSB

b. DSBSC

c. PDM

d. PCM

View Answer:

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

View Answer:

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

View Answer:

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

View Answer:

Answer: Option B

Solution:

28. “Bit-stuffing” is more formally called:

a. compensation

b. rectification

c. justification

d. frame alignment

View Answer:

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

View Answer:

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

View Answer:

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

View Answer:

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

View Answer:

Answer: Option A

Solution:

COMPLETION

1. A ____________________ is a local calling area.

View Answer:

Answer: LATA

Solution:

2. Central offices are connected together by ____________________ lines.

View Answer:

Answer: trunk

Solution:

3. One central office can be connected to another through a ____________________ office.

View Answer:

Answer: tandem

Solution:

4. With 7-digit phone numbers, ____________________ thousand telephones can connect to a central office.

View Answer:

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.

View Answer:

Answer: blocking

Solution:

6. New ____________________ switching equipment uses TDM to combine signals.

View Answer:

Answer: digital

Solution:

7. Most local loops still use ____________________ copper wire.

View Answer:

Answer: twisted-pair

Solution:

8. As compared to a hierarchical network, a ____________________ network never needs more than one intermediate switch.

View Answer:

Answer: flat

Solution:

9. ____________________ coils were used to reduce the attenuation of voice frequencies.

View Answer:

Answer: Loading

Solution:

10. In a twisted-pair telephone cable, the red wire is called ____________________.

View Answer:

Answer: ring

Solution:

11. In a twisted-pair telephone cable, the green wire is called ____________________.

View Answer:

Answer: tip

Solution:

12. Of the red and green ‘phone wires, the ____________________ wire is positive with respect to the other.

View Answer:

Answer: green

Solution:

13. A telephone is said to have ____________________ the line when the central office sends it dial tone.

View Answer:

Answer: seized

Solution:

14. The ____________________ functions are provided by a SLIC.

View Answer:

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.

View Answer:

Answer: hybrid

Solution:

16. In a crosspoint switch, not all ____________________ can be in use at the same time.

View Answer:

Answer: lines

Solution:

17. The old carbon transmitters generated a relatively ____________________ signal voltage.

View Answer:

Answer: large

Solution:

18. The generic term for Touch-Tone® signaling is ____________________.

View Answer:

Answer: DTMF

Solution:

19. A ____________________ line provides more bandwidth than a standard line.

View Answer:

Answer: conditioned

Solution:

20. In the telephone system, amplifiers are called ____________________.

View Answer:

Answer: repeaters

Solution:

21. An echo ____________________ converts a long-distance line from full-duplex to half-duplex operation.

View Answer:

Answer: suppresor

Solution:

22. ____________________ weighting is an attempt to adjust the noise or signal level to the response of a typical telephone receiver.

View Answer:

Answer: C-message

Solution:

23. In FDM telephony, the modulation is usually ____________________.

View Answer:

Answer: SSB / SSBSC

Solution:

24. In FDM telephony, ____________________ bands separate the channels in a group.

View Answer:

Answer: guard

Solution:

25. Because of “bit robbing”, a channel in a DS-1 frame allows only ____________________ kbps when used to send digital data.

View Answer:

Answer: 56

Solution:

26. A ____________________ is a group of 12 DS-1 frames with signaling information in the sixth and twelfth frames.

View Answer:

Answer: superframe

Solution:

27. In DS-1C, ____________________ bits are used to compensate for differences between clock rates.

View Answer:

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.

View Answer:

Answer: in-channel

Solution:

29. SS7 is the current version of _________________________ signaling.

View Answer:

Answer: common-channel

Solution:

30. SS7 is a ____________________-switched data network.

View Answer:

Answer: packet

Solution:

31. In ISDN, the ____________________ channel is used for common-channel signaling.

View Answer:

Answer: D

Solution:

32. In ISDN, the ____________________ channels are used for voice or data.

View Answer:

Answer: B

Solution:

33. Terminal equipment especially designed for ISDN is designated ____________________ equipment.

View Answer:

Answer: TE1

Solution:

34. The A in ADSL stands for ____________________.

View Answer:

Answer: asymmetrical

Solution:

35. In ADSL, the speed from the network to the subscriber is ____________________ than the speed in the opposite direction.

View Answer:

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?

View Answer:

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?

View Answer:

Answer: 200 ohms

Solution:

3. Which two DTMF tones correspond to the digit “1”? (Use the table in the text.)

View Answer:

Answer: 697 Hz and 1209 Hz

Solution:

4. Calculate the dB of VNL required for a channel with a 3 ms delay.

View Answer:

Answer: 1 dB

Solution:

5. If a telephone voice signal has a level of 0 dBm, what is its level in dBrn?

View Answer:

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?

View Answer:

Answer: 65 dBrnc TLP

Solution:

Complete List of MCQ in Electronic Communication Systems by Blake

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