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Digital Communications Quiz

Total questions: 20

Worksheet time: 10mins

Name
Class
Date
1.

Probability of error for QPSK technique is

a)

erfc (EbNo)

b)

12erfc (EbNo)

c)

12erfc (Eb2No)

d)

None of the above

2.

Matched filter

a)

Is a non-linear filter

b)

Produces maximum output SNR

c)

All of the mentioned

d)

None of the mentioned

3.

Base band signal receiver is also called as Integrate and Dump filter receiver.

a)

True

b)

False

4.

Which has same probability of error?

a)

ASK and FSK

b)

ASK and PSK

c)

PSK and FSK

d)

None of the mentioned

5.

Which of the following relation is correct for average of Mutual Information I(X, Y)

a)

H(X) + H(Y) - H (X, Y)

b)

H(X) + H(Y) + H (X, Y)

c)

H(X) - H(Y) - H (X, Y)

d)

H(X) - H(Y) + H (X, Y)

6.

Information rate is defined as

a)

Information per unit time

b)

Average number of bits of information per second

c)

r.H, r- sampling rate and H- entropy

d)

All of the above

7.

Information content of an event is directly proportional to its probability of occurrence.

a)

True

b)

False

8.

Channel capacity is _________________ proportional to Bandwidth.

a)

Inversely

b)

Directly

9.

Efficiency of Source coding for Partitioning / Reduction value M=2 is

a)

H(X)/2L

b)

H(X)/L

c)

2.H(X)/L

d)

H(X)/4L

10.

Entropy of N random variables is the _____ of the entropy of individual random variable.

a)

Sum

b)

Product

c)

Sum of squares

d)

Average

11.

The channel capacity is measured in terms of:

a)

Bits per channel

b)

Number of input channel connected

c)

Calls per channel

d)

Number of output channel connected

12.

The code length does not depend on the frequency of occurrence of characters.

a)

True

b)

False

13.

The received code contains an error if the syndrome vector is

a)

Infinity

b)

Zero

c)

non-Zero

d)

None of the mentioned

14.

Which of the following is not a way to represent convolution code?

a)

State diagram

b)

Trellis diagram

c)

Tree diagram

d)

Linear matrix

15.

The minimum distance of an (n,k)=(7,4) linear block code is

a)

1

b)

2

c)

3

d)

4

16.

For a (7, 4) block code, 7 is the total number of bits and 4 is the number of

a)

Message bits

b)

Redundant bits

c)

Total bits- information bits

d)

None of the above

17.

A linear code in which

a)

Sum of code words is also a code word

b)

All-zero code word is a code word

c)

Minimum hamming distance between two code words is equal to weight of any non-zero code word

d)

All of the above

18.

The capacity of an independent channel is

a)

0

b)

1

c)

∞

d)

None of the above

19.

The cyclic codes are designed using

a)

Shift registers with feedback

b)

Shift registers without feedback

c)

Flipflops

d)

None of the mentioned

20.

Example for convolution encoder state diagram is

a)

Tree diagram

b)

Trellis diagram

c)

Tree & Trellis diagram

d)

None of the mentioned