Blake: MCQs in The Telephone System

Multiple Choice Questions in The Telephone System from the book Electronic Communication Systems by Roy Blake. Make sure to familiarize each and every questions

Blake: MCQs in The Telephone System

This is the Multiple Choice Questions in Chapter 8: The Telephone System from the book Electronic Communication Systems by Roy Blake. 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.

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

ANS: C

2. PSTN stands for:

  • a. Public Switched Telephone Network
  • b. Private Switched Telephone Network
  • c. Primary Service Telephone Network
  • d. Primary Service Telephone Numbers

ANS: A

3. POTS stands for:

  • a. Private Office Telephone System
  • b. Primary Office Telephone Service
  • c. Primary Operational Test System
  • d. Plain Old Telephone Service

ANS: D

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

ANS: A

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

ANS: A

6. Central offices are connected by:

  • a. local loops
  • b. trunk lines
  • c. both a and b
  • d. none of the above

ANS: B

7. Local loops terminate at:

  • a. a tandem office
  • b. a toll station
  • c. a central office
  • d. an interexchange office

ANS: C

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

ANS: D

9. In telephony, POP stands for:

  • a. Post Office Protocol
  • b. Point Of Presence
  • c. Power-On Protocol
  • d. none of the above

ANS: B

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

ANS: A

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

ANS: D

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

ANS: B

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

ANS: B

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

ANS: D

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

ANS: C

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

ANS: A

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

ANS: D

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

ANS: C

19. VNL stands for:

  • a. voltage net loss
  • b. volume net loss
  • c. via net loss
  • d. voice noise level

ANS: C

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

ANS: B

21. The reference noise level for telephony is:

  • a. 1 mW
  • b. 0 dBm
  • c. 1 pW
  • d. 0 dBr

ANS: C

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

  • a. 6
  • b. 12
  • c. 24
  • d. 60

ANS: B

23. Basic FDM groups can be combined into:

  • a. supergroups
  • b. mastergroups
  • c. jumbogroups
  • d. all of the above

ANS: D

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

  • a. SSB
  • b. DSBSC
  • c. PDM
  • d. PCM

ANS: A

25. PABX stands for:

  • a. Power Amplification Before Transmission
  • b. Private Automatic Branch Exchange
  • c. Public Automated Branch Exchange
  • d. Public Access Branch Exchange

ANS: B

26. SLIC stands for:

  • a. Single-Line Interface Circuit
  • b. Standard Line Interface Card
  • c. Subscriber Line Interface Card
  • d. Standard Local Interface Circuit

ANS: C

27. In DS-1, bits are "robbed" in order to:

  • a. provide synchronization
  • b. carry signaling
  • c. cancel echoes
  • d. check for errors

ANS: B

28. "Bit-stuffing" is more formally called:

  • a. compensation
  • b. rectification
  • c. justification
  • d. frame alignment

ANS: C

29. ISDN stands for:

  • a. Integrated Services Digital Network
  • b. Information Services Digital Network
  • c. Integrated Services Data Network
  • d. Information Systems Digital Network

ANS: A

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

ANS: D

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

ANS: B

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

ANS: A

COMPLETION

1. A ____________________ is a local calling area.

ANS: LATA

2. Central offices are connected together by ____________________ lines.

ANS: trunk

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

ANS: tandem

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

ANS: ten

5. Call ____________________ is when it becomes impossible for a subscriber to place a call due to an overload of lines being used.

ANS: blocking

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

ANS: digital

7. Most local loops still use ____________________ copper wire.

ANS: twisted-pair

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

ANS: flat

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

ANS: Loading

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

ANS: ring

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

ANS: tip

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

ANS: green

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

ANS: seized

14. The ____________________ functions are provided by a SLIC.

ANS: BORSCHT

15. A ____________________ coil prevents loss of signal energy within a telephone while allowing full-duplex operation over a single pair of wires.

ANS: hybrid

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

ANS: lines

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

ANS: large

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

ANS: DTMF

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

ANS: conditioned

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

ANS: repeaters

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

ANS: suppressor

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

ANS: C-message

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

ANS:

SSB

SSBSC

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

ANS: guard

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

ANS: 56

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

ANS: superframe

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

ANS: stuff

28. Busy and dial tone are referred to as ____________________ signals because they use the same pair of wires as the voice signal.

ANS: in-channel

29. SS7 is the current version of _________________________ signaling.

ANS: common-channel

30. SS7 is a ____________________-switched data network.

ANS: packet

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

ANS: D

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

ANS: B

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

ANS: TE1

34. The A in ADSL stands for ____________________.

ANS: asymmetrical

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

ANS:

greater

faster

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?

ANS:

1000 ohms

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?

ANS:

200 ohms

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

ANS:

697 Hz and 1209 Hz

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

ANS:

1 dB

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

ANS:

90 dBrn

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?

ANS:

65 dBrnc TLP

Complete List of MCQs in Electronic Communication Systems by Blake



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