# Forouzan: MCQ in Digital Transmission

(Last Updated On: December 28, 2017)

This is the MCQ in Digital Transmission from book the Data Communications and Networking 4th Edition by Behrouz A. Forouzan. If you are looking for a reviewer in datacom, a topic in Electronics Systems and Technologies (Communications Engineering) this will definitely help you before taking the Board Exam.

Let’s see how well you understand how the information transformed to digital signal so that it can be transmitted from one point to another. You can always visit the summary of the lessons. Digital Transmission.

#### Begin and Good luck!

Choose the letter of the best answer in each questions.

1. Which of the following encoding methods does not provide for synchronization?

• A)   RZ
• B)   NRZ-L
• C)   NRZ-I
• D)   Manchester

Solution:

2. If the frequency spectrum of a signal has a bandwidth of 500 Hz with the highest frequency at 600 Hz, what should be the sampling rate, according to the Nyquist theorem?

• A)   200 samples/s
• B)   500 samples/s
• C)   1000 samples/s
• D)   1200 samples/s

Solution:

3. In asynchronous transmission, the gap time between bytes is _______.

• A)   variable
• B)   fixed
• C)   zero
• D)   a function of the data rate

Solution:

4. ______ substitutes eight consecutive zeros with 000VB0VB.

• A)   B4B8
• B)   B8ZS
• C)   HDB3
• D)   none of the above

Solution:

5. The most common technique to change an analog signal to digital data is called __________.

• A)   sampling
• B)   PAL
• C)   PCM
• D)   none of the above

Solution:

6. The minimum bandwidth of Manchester and differential Manchester is ____ that of NRZ.

• A)   the same as
• B)   twice
• C)   thrice
• D)   none of the above

Solution:

7. The signal rate is sometimes called the ____ rate.

• A)   bit
• B)   baud
• C)   signal
• D)   none of the above

Solution:

8. Unipolar, bipolar, and polar encoding are types of _______ encoding.

• A)   line
• B)   block
• C)   NRZ
• D)   Manchester

Solution:

9. ________ is normally referred to as mB/nB coding; it replaces each m-bit group with an n-bit group.

• A)   Line coding
• B)   Block coding
• C)   Scrambling
• D)   None of the above

Solution:

10. In ______ schemes, the voltages are on the both sides of the time axis. For example, the voltage level for 0 can be positive and the voltage level for 1 can be negative.

• A)   unipolar
• B)   bipolar
• C)   polar
• D)   all of the above

Solution:

11. The ________ rate defines the number of data elements sent in 1s; the ______ rate is the number of signal elements sent in 1s.

• A)   signal; data
• B)   data; signal
• C)   baud; bit
• D)   none of the above

Solution:

12. The idea of RZ and the idea of NRZ-L are combined into the ________ scheme.

• A)   Manchester
• B)   differential Manchester
• C)   both (a) and (b)
• D)   neither (a) nor (b)

Solution:

13. ________ provides synchronization without increasing the number of bits.

• A)   Line coding
• B)   Block coding
• C)   Scrambling
• D)   None of the above

Solution:

14. The Nyquist theorem specifies the minimum sampling rate to be_______.

• A)   equal to the lowest frequency of a signal
• B)   equal to the highest frequency of a signal
• C)   twice the bandwidth of a signal
• D)   twice the highest frequency of a signal

Solution:

15. PCM is an example of _______ conversion.

• A)   analog-to-analog
• B)   analog-to-digital
• C)   digital-to-digital
• D)   digital-to-analog

Solution:

16. There are three sampling methods: __________.

• A)   ideal, natural, and flat-top
• B)   ideal, sampled, and flat-top
• C)   quantized, sampled, and ideal
• D)   none of the above

Solution:

17. In _______encoding, we use three levels: positive, zero, and negative.

• A)   unipolar
• B)   polar
• C)   bipolar
• D)   none of the above

Solution:

18. Block coding can help in _______ at the receiver.

• A)   Synchronization
• B)   Error detection
• C)   Attenuation
• D)   (a) and (b)

Solution:

19. In Manchester and differential Manchester encoding, the transition at the middle of the bit is used for __________.

• A)   bit transfer
• B)   synchronization
• C)   baud transfer
• D)   none of the above

Solution:

20. _______ encoding has a transition at the beginning of each 0 bit.

• A)   Differential Manchester
• B)   Manchester
• C)   RZ
• D)   All the above

Solution:

21. In ______, the change or lack of change in the level of the voltage determines the value of the bit.

• A)   NRZ-L
• B)   NRZ-I
• C)   both (a) and (b)
• D)   neither (a) nor (b)

Solution:

22. In ___________ there is always a transition at the middle of the bit, but the bit values are determined at the beginning of the bit. If the next bit is 0, there is a transition; if the next bit is 1, there is none.

• A)   Manchester
• B)   differential Manchester
• C)   both (a) and (b)
• D)   neither (a) nor (b)

Solution:

23. In _______ encoding, the duration of the bit is divided into two halves. The voltage remains at one level during the first half and moves to the other level in the second half. The transition at the middle of the bit provides synchronization.

• A)   Manchester
• B)   differential Manchester
• C)   both (a) and (b)
• D)   neither (a) nor (b)

Solution:

24. The ________ mode provides synchronization for the entire stream of bits must. In other words, it guarantees that the data arrive at a fixed rate.

• A)   isochronous
• B)   synchronous
• C)   asynchronous
• D)   none of the above

Solution:

25. The idea of RZ and the idea of NRZ-I are combined into the ________ scheme.

• A)   Manchester
• B)   differential Manchester
• C)   both (a) and (b)
• D)   neither (a) nor (b)

Solution:

Forouzan: MCQ in Digital Transmission
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