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Blake: MCQ in Digital Modulation and Modems

Blake: MCQ in Digital Modulation and Modems

This is the Multiple Choice Questions in Chapter 12: Digital Modulation and Modems from the book Electronic Communication Systems by Roy BlakeBlake: MCQ in Digital Modulation and Modems. 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. FSK stands for:

a. Full-Shift Keying

b. Frequency-Shift Keying

c. Full-Signal Keying

d. none of the above

View Answer:

Answer: Option B

Solution:

2. PSK stands for:

a. Pulse-Signal Keying

b. Pulse-Shift Keying

c. Phase-Signal Keying

d. Phase-Shift Keying

View Answer:

Answer: Option D

Solution:

3. QAM stands for:

a. Quadrature Amplitude Modulation

b. Quadrature Amplitude Masking

c. Quadrature Amplitude Marking

d. none of the above

View Answer:

Answer: Option A

Solution:

4. In the equation I = ktB, I is measured in:

a. amperes

b. amperes per second

c. bits

d. bits per second

View Answer:

Answer: Option C

Solution:

5. In the equation C = 2Blog2M, M is the:

a. margin of noise

b. modulation index

c. number of possible states per symbol

d. maximum number of symbols per second

View Answer:

Answer: Option C

Solution:

6. An “eye pattern” shows a good channel when:

a. the eye is maximally open

b. the eye is maximally closed

c. the eye is half open

d. the eye alternately opens and closes

View Answer:

Answer: Option A

Solution:

7. What you see in an eye pattern is the effect of:

a. too many bits high

b. too many bits low

c. intermodulation distortion

d. intersymbol interference

View Answer:

Answer: Option D

Solution:

8. High-frequency radioteletype systems commonly use:

a. FSK

b. AFSK

c. PSK

d. QAM

View Answer:

Answer: Option A

Solution:

9. Instead of a single bit, a QPSK symbol contains:

a. a byte

b. 4 bits

c. a dibit

d. a Q-bit

View Answer:

Answer: Option C

Solution:

10. To reduce the need for linearity, π/4 DQPSK uses:

a. angles of 0, 90, 180, and 270 degrees

b. angles of 45, 135, 225, and 315 degrees

c. angles of π/4, 2π/4, 3π/4, and 4π/4

d. double phase-shift angles

View Answer:

Answer: Option B

Solution:

11. For QAM, a “constellation diagram” shows:

a. location of symbols in “symbol space”

b. separation of symbols in “symbol space”

c. effects of noise on symbols

d. all of the above

View Answer:

Answer: Option D

Solution:

12. For QAM, the two dimensions of its symbol space are:

a. amplitude and frequency

b. amplitude and phase angle

c. frequency and phase angle

d. I-bits and Q-bits

View Answer:

Answer: Option B

Solution:

13. The specs of the old Bell type 103 modem were:

a. 300 bps, full-duplex, FSK

b. 600 bps, full-duplex, FSK

c. 1200 bps, full-duplex, FSK

d. 1200 bps, half-duplex, FSK

View Answer:

Answer: Option A

Solution:

14. ITU is an abbreviation for:

a. International Telephony Unit

b. International Telephony Union

c. International Telecommunications Union

d. International Telecommunications Units

View Answer:

Answer: Option C

Solution:

15. The ITU is under the auspices of:

a. CCITT

b. the U.N.

c. IEEE

d. ANSI

View Answer:

Answer: Option B

Solution:

16. High-speed modems equalize the line to compensate for:

a. noise and interference

b. uneven phase and frequency response

c. low SNR

d. inconsistent bit rates at either end of channel

View Answer:

Answer: Option B

Solution:

17. The bits sent to allow equalization are called:

a. Gaussian bits

b. random bits

c. a training sequence

d. a random sequence

View Answer:

Answer: Option C

Solution:

18. The V.90 standard is issued by:

a. the EIA

b. the TIA

c. the ITU

d. the ISO

View Answer:

Answer: Option C

Solution:

19. MNP2, MNP3, MNP4, and MNP10 are all:

a. data-compression schemes

b. error-correction protocols

c. both a and b

d. none of the above

View Answer:

Answer: Option B

Solution:

20. MNP5 and V.42 bis are both:

a. data-compression schemes

b. error-correction protocols

c. both a and b

d. none of the above

View Answer:

Answer: Option A

Solution:

21. In RS-232, flow control is done using:

a. RTS/CTS handshake

b. XON/XOFF characters

c. both a and b

d. none of the above

View Answer:

Answer: Option C

Solution:

22. The official name for RS-232C is:

a. RS-232C

b. EIA-232D

c. ISO-232C/D

d. ANSI-232C

View Answer:

Answer: Option B

Solution:

23. In RS-232, a modem would be:

a. a DTR

b. a DSR

c. a DCE

d. a DTE

View Answer:

Answer: Option C

Solution:

24. In RS-232, a personal computer would be:

a. a DTR

b. a DSR

c. a DCE

d. a DTE

View Answer:

Answer: Option D

Solution:

25. On a DB-9 RS-232 connector, signal ground is pin:

a. 1

b. 3

c. 5

d. 7

View Answer:

Answer: Option C

Solution:

26. On a DB-25 RS-232 connector, signal ground is pin:

a. 1

b. 3

c. 5

d. 7

View Answer:

Answer: Option D

Solution:

27. The minimum lines required for RS-232 are:

a. TD and RD

b. TD, RD, and signal ground

c. TD, RD, DSR, and signal ground

d. TD, RD, RTS, CTS, and signal ground

View Answer:

Answer: Option B

Solution:

28. Hardware flow control uses:

a. XON and XOFF

b. TD and RD

c. RTS and CTS

d. DSR and DCD

View Answer:

Answer: Option C

Solution:

29. Software flow control uses:

a. XON and XOFF

b. TD and RD

c. RTS and CTS

d. DSR and DCD

View Answer:

Answer: Option A

Solution:

30. Which voltage represents a binary zero on an RS-232 data pin:

a. +15 volts

b. +12 volts

c. +9 volts

d. all of the above

View Answer:

Answer: Option D

Solution:

31. DSL stands for:

a. Data Signal Line

b. Digital Signal Line

c. Digital Subscriber Line

d. Double-Speed Loop

View Answer:

Answer: Option C

Solution:

32. ADSL stands for:

a. Asynchronous DSL

b. Asymmetrical DSL

c. Analog DSL

d. All DSL

View Answer:

Answer: Option B

Solution:

33. In a CATV system, HFC stands for:

a. Head Frequency Control

b. Hybrid Frequency Control

c. Hybrid Fiber-Coax

d. Hybrid Fiber Control

View Answer:

Answer: Option C

Solution:

34. In a CATV system, CMTS stands for:

a. Cable Modem Terminal Server

b. Cable Modem Transmission System

c. Cable Modem Terminal System

d. Cable Modem Transmission Server

View Answer:

Answer: Option A

Solution:

35. A “splitter” at the subscriber end is not required for:

a. Any DSL scheme

b. ADSL

c. ADSL Lite

d. none of the above

View Answer:

Answer: Option C

Solution:

COMPLETION

1. RTS means Request To ____________________.

View Answer:

Answer: Send

Solution:

2. The response to RTS is ____________________.

View Answer:

Answer: CTS

Solution:

3. FSK stands for Frequency-Shift ____________________.

View Answer:

Answer: Keying

Solution:

4. DSR stands for ____________________ Set Ready.

View Answer:

Answer: Data

Solution:

5. QAM stands for ____________________ Amplitude Modulation.

View Answer:

Answer: Quadrature

Solution:

6. The number of symbols per second is called the ____________________ rate.

View Answer:

Answer: baud

Solution:

7. The 2 bits of information in a QPSK symbol is called a ____________________.

View Answer:

Answer: dibit

Solution:

8. QPSK uses ____________________ different phase angles.

View Answer:

Answer: four

Solution:

9. DPSK stands for ____________________ PSK.

View Answer:

Answer: Delta

Solution:

10. The QAM amplitude-phase combinations are shown with a ____________________ diagram.

View Answer:

Answer: constellation

Solution:

11. ITU stands for International _________________________ Union.

View Answer:

Answer: Telecommunications

Solution:

12. In QAM modems, ____________________ coding adds extra bits to improve performance on a noisy line.

View Answer:

Answer: Trellis

Solution:

13. ____________________ is used in a high-speed modem to compensate for uneven frequency and phase response on a line.

View Answer:

Answer: Equalization

Solution:

14. The maximum allowed speed for a modem on a dial-up line is about ____________________ bps.

View Answer:

Answer: 54k

Solution:

15. The nominal maximum speed on an RS-232 cable is ____________________ bps.

View Answer:

Answer: 20k

Solution:

16. In RS-232, the ____________________ line is asserted when the analog carrier from another modem is being received.

View Answer:

Answer:
CD

DCD

RLSD

Solution:

17. Between hardware flow control and software flow control, ____________________ flow control is preferred.

View Answer:

Answer: hardware

Solution:

18. A voltage higher than ____________________ volts should be considered a high on an RS-232 receiver.

View Answer:

Answer: 3

Solution:

19. A ____________________ modem cable is used to connect two DTEs via their serial ports.

View Answer:

Answer: null

Solution:

20. ADSL stands for ____________________ DSL.

View Answer:

Answer: Asymmetrical

Solution:

21. A typical CATV system is organized as a ____________________ network.

View Answer:

Answer: tree

Solution:

22. In a CATV system using cable modems, a ____________________ is used to put several channels of data onto a fiber-optic backbone.

View Answer:

Answer: CMTS

Solution:

23. ____________________ is the process of synchronizing transmitted data from cable modems to a CMTS.

View Answer:

Answer: Ranging

Solution:

24. ____________________ systems send high-speed data over a POTS line while sharing the line with dialup service.

View Answer:

Answer: ADSL

Solution:

25. The ____________________ version of ADSL does not require a splitter at the subscriber end.

View Answer:

Answer: lite

Solution:

26. ____________________ modulation divides the line bandwidth into many narrow bands called tones or bins for ADSL.

View Answer:

Answer: DMT

Solution:

27. A DSLAM is a DSL Access ____________________.

View Answer:

Answer: Multiplexer

Solution:

SHORT ANSWER

1. Calculate the bits per second capacity of a system sending 1000 symbols per second with 16 possible states per symbol.

View Answer:

Answer: 4000

Solution:

2. How many points will be on the constellation diagram of a QAM system using 8 phase angles and 2 amplitude levels?

View Answer:

Answer: 16

Solution:

3. A CATV system has 100 cable-modem customers sharing a single channel with a data rate of 36 Mbps. If half the modems are active at any given time, what bit rate can a customer expect?

View Answer:

Answer: 720 kbps

Solution:

4. A DMT system uses 4.3-kHz bins on a 1-MHz cable. Approximately how many bins are there?

View Answer:

Answer: 230

Solution:

5. Assuming a maximum symbol rate of 400 per second, how many possible states must a symbol have to achieve a data rate of 1200 bps?

View Answer:

Answer: 8

Solution:

Complete List of MCQ in Electronic Communication Systems by Blake

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