Information Theory And Coding MCQ Questions & Answers

41

A source generates four messages with probability $$\frac{1}{8},\,\frac{1}{8},\,\frac{1}{4}$$ and $$\frac{1}{2}.$$ What is the entropy of the source (bits/message)?

A) 1 B) 1.75 C) 2 D) 4

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Answer & Solution

Answer: Option B

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42

A source has two symbols x₁ and x₂ with probabilities P₁ and P₂ respectively. If a new source, with four symbols is generated from the above source, then the new symbol probabilities will be (ε is a number such that 0 < ε < 1)

A) P₁, P₂, P₁, P₂ B) P₁, P₁, P₂, P₂ C) (1 - ε)P₁, (1 - ε)P₂, εP₁, εP₂ D) $$\frac{{{{\text{P}}_1}}}{4},\,\frac{{{{\text{P}}_2}}}{4},\,\frac{{{{\text{P}}_1}}}{4},\,\frac{{{{\text{P}}_2}}}{4}$$

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Answer & Solution

Answer: Option C

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43

A digital communication system transmits a block of N bits. The probability of error in decoding a bit is α. The error event of each bit is independent of the error events of the other bits. The received block is declared erroneous if at least one of the its bits is decoded wrongly. The probability that the received block is erroneous is

A) N(1 - α) B) 1 - (1 - α)^N C) 1 - α^N D) α^N

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Answer & Solution

Answer: Option B

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44

An Ideal power limited communication channel with additive white Gaussian noise with 1 MHz band width and Signal to Noise ratio of 15 is transmitting the information at theoretical maximum rate. If the Signal to Noise ratio is reduced to 7, how much bandwidth is required to maintain same rate:

A) $$\frac{{15}}{7}$$ MHz B) $$\frac{4}{3}$$ MHz C) 2 MHz D) None of these

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Answer & Solution

Answer: Option B

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45

The input to a channel is a band-pass signal. It is obtained by linearly modulating a sinusoidal carrier with a single-tone signal. The output of the channel due to this input is given by Y(t) = $$\left( {\frac{1}{{100}}} \right)$$ cos(100t - 10^-6)cos(10⁶t - 1.56)
The group delay (t_g) and the phase delay (t_p) in seconds, of the channel are

A) t_g = 1.56, t_p = 10^-6 B) t_g = 1.56 (10⁸), t_p = 10^-6 C) t_g = 10^-8, t_p = 1.56(10^-6) D) t_g = 10^-6, t_p = 1.56

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Answer & Solution

Answer: Option C

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46

Consider a discrete memory-less source with source alphabet, S = {S₀, S₁, S₂, S₃, S₄} with respective probabilities of P = {0.4, 0.2, 0.2, 0.1, 0.1}. Find the average code word length

A) 2.2 B) 2.4 C) 2 D) 2.1

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Answer & Solution

Answer: Option A

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47

Bits 1 and 0 are transmitted with equal probability. At the receiver, the pdf of the respective received signals for both bits are as shown below:
If the detection threshold is 1, the BER will be
Information Theory and Coding mcq question image

Information Theory and Coding mcq question image

A) $$\frac{1}{2}$$ B) $$\frac{1}{4}$$ C) $$\frac{1}{8}$$ D) $$\frac{1}{{16}}$$

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Answer & Solution

Answer: Option C

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48

The channel capacity is measured in terms of:

A) bits per channel B) number of input channels connected C) calls per channel D) number of output channels connected

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Answer & Solution

Answer: Option A

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49

As per Shannon's channel capacity theorem, if samples are transmitted in 'T' seconds over a noisy channel which is bandlimited to 'B' Hz. The number of samples 'n' is given by (Symbols/notations carry their usual meaning)

A) B/T B) T/B C) 2BT D) BT/2

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Answer & Solution

Answer: Option C

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50

In communication system a trade-off can be made between transmission bandwidth and

A) output SNR B) input SNR C) channel capacity D) none of these

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Answer & Solution

Answer: Option A

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Information Theory And Coding MCQ Questions & Answers | ECE