ESAT Forouzan - Chapter 4: Digital Transmission

Question 1

Unipolar, bipolar and polar encoding are types of _______ encoding
a. Line
b. Block
c. NRZ
d. Manchester

Answer 1

a. Line

Question 2

If a symbol is composed of 3 bits, there are __________ data levels.
a. 2
b. 4
c. 8
d. 16

Answer 2

c. 8

Question 3

Pulse rate is always ______ the bit rate
a. Greater than
b. Less than
c. Greater than or equal to
d. Less than or equal to

Answer 3

d. Less than or equal to

Question 4

________ encoding has a transition at the middle of each bit.
a. RZ
b. Manchester
c. Differential Manchester
d. All the above

Answer 4

d. All the above

Question 5

________ encoding has a transition at the beginning of each 0 bit.
a. RZ
b. Manchester
c. Differential Manchester
d. All the above

Answer 5

c. Differential Manchester

Question 6

PCM is an example of ______ conversion.
a. Digital-to-digital
b. Digital-to-analog
c. Analog-to-analog
d. Analog-to-Digital

Answer 6

d. Analog-to-Digital

Question 7

7. If the frequency spectrum of a signal has 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

Answer 7

d. 1200 samples/s

Question 8

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

Answer 8

d. Twice the highest frequency of a signal

Question 9

One factor in the accuracy of a reconstructed PCM signal is the __________.
a. Signal bandwidth
b. Carrier frequency
c. Number of bits used for quantization
d. Baud rate

Answer 9

c. Number of bits used for quantization

Question 10

Which encoding type always has nonzero average amplitude
a. Unipolar
b. Polar
c. Bipolar
d. All the above

Answer 10

a. Unipolar

Question 11

Which of the following encoding methods does not provide for synchronization?
a. NRZ-L
b. RZ
c. NRZ-I
d. Manchester

Answer 11

a. NRZ-L

Question 12

Which encoding method uses alternating positive and negative values for 1s?
a. NRZ-I
b. RZ
c. Manchester
d. AMI

Answer 12

d. AMI

Question 13

In PCM, an analog-to-____________ conversion occurs.
a. Analog
b. Digital
c. QAM
d. Differential

Answer 13

b. Digital

Question 14

If the maximum value of a PCM signal is 31 and the minimum value is -31, how many bits were used for conding?
a. 4
b. 5
c. 6
d. 7

Answer 14

c. 6

Question 15

RZ encoding involves _________ signal levels.
a. Two
b. Three
c. Four
d. Five

Answer 15

b. Three

Question 16

Which quantization level results in a more faithful reproduction of the signal
a. 2
b. 8
c. 16
d. 32

Answer 16

d. 32

Question 17

Which encoding technique attempts to solve the loss of synchronization due to long strings of 0s.
a. BnZS
b. NRZ
c. AMI
d. (a) and (b)

Answer 17

a. BnZS

Question 18

Block coding can help in __________ at the receiver.
a. Synchronizations
b. Error detection
c. Attenuation
d. (a) and (b)

Answer 18

d. (a) and (b)

Question 19

In ____________ transmission, bits are transmitted simultaneously, each across its own wire.
a. Asynchronous serial
b. Synchronous serial
c. Parallel
d. (a) and (b)

Answer 19

c. Parallel

Question 20

In ________ transmission, bits are transmitted over a single wire, one at a time.
a. Asynchronous serial
b. Synchronous serial
c. Parallel
d. (a) and (b)

Answer 20

d. (a) and (b)

Question 21

In __________ transmission, a start bit and stop bit frame a character byte.
a. Asynchronous serial
b. Synchronous serial
c. Parallel
d. (a) and (b)

Answer 21

a. Asynchronous serial

Question 22

In asynchronous transmission, the gap time between bytes is ________.
a. Fixed
b. Variable
c. A function of the data rate
d. Zero

Answer 22

b. Variable

Question 23

Synchronous transmission does not have __________.
a. A start bit
b. A stop bit
c. Gaps between bytes
d. All the above

Answer 23

d. All the above