STUPIDSID
1 (a)
Discuss channel capacity of a discrete memoriless channel with an arbitrary
number of inputs.
7 M
Answer the following questions:
1 (b) (i)
Justify "For finite signal and noise powers, the channel capacity always
remains finite"
3 M
1 (b) (ii)
A random experiment consists of drawing two cards from a deck in
succession (without replacing the first card drawn). Assign a value to the
probability of obtaining two red aces in two draws.
3 Show that if two random variables are independent then they are uncorrelated.
3 Show that if two random variables are independent then they are uncorrelated.
4 M
2 (a)
Illustrate the problems of delta modulation with necessary waveforms. Explain
how adaptive delta modulation corrects these problems.
7 M
2 (b)
The Rayleigh density is characterized by the PDF.
\[p,(r)=\left\{\begin{matrix} \dfrac{r}{\sigma ^{2}}e^{-r^{2}} &/2\sigma^{2} &r\ge &0 \\0 & & r<&0 \end{matrix}\right.\]
Show that Rayleigh random variable can be derived from two independent Gaussian random variables.
\[p,(r)=\left\{\begin{matrix} \dfrac{r}{\sigma ^{2}}e^{-r^{2}} &/2\sigma^{2} &r\ge &0 \\0 & & r<&0 \end{matrix}\right.\]
Show that Rayleigh random variable can be derived from two independent Gaussian random variables.
7 M
2 (c)
A source emits seven messages with probabilities 1/3, 1/3, 1/9, 1/9, 1/27, 1/27,
and 1/27, respectively.
1. Obtain the compact 3-ary code and find code efficiency of the code
2. Obtain the compact binary code.
1. Obtain the compact 3-ary code and find code efficiency of the code
2. Obtain the compact binary code.
7 M
3 (a)
Explain Probability Density Function (PDF) of random variable with its
properties. The PDF of amplitude x of a certain signal x(t) is given by
px=0.5|x|e-|x|
1. Find the probability that -1 < x ≤ 2.
2. Determine mean and the variance of the RV x.
px=0.5|x|e-|x|
1. Find the probability that -1 < x ≤ 2.
2. Determine mean and the variance of the RV x.
7 M
Answer the following questions:
3 (b) (i)
A signal m(t) of bandwidth B=4kHz is transmitted using a binary
companded PCM with μ=100. Compare the cases of L=16 & L=128 from the point of view of transmission bandwidth and the output SNR.
4 M
3 (b) (ii)
Describe quantization noise in a PCM.
3 M
3 (c)
For a (6,2) linear block code, the generator matrix G is
\[G=\begin{bmatrix} 1 &0 &1 &1 &1 &0 \\0 &1 &1 &0 &1 &1 \end{bmatrix}\]
1. Construct the code table for this code and determine the minimum distance between code-words.
2. Prepare a suitable decoding table.
\[G=\begin{bmatrix} 1 &0 &1 &1 &1 &0 \\0 &1 &1 &0 &1 &1 \end{bmatrix}\]
1. Construct the code table for this code and determine the minimum distance between code-words.
2. Prepare a suitable decoding table.
7 M
Answer the following questions:
3 (d) (i)
Using general expression for finding Power Spectral Density (PSD), find
PSD of an on-off signaling.
4 M
3 (d) (ii)
Draw the schematic of a regenerative repeater.
3 M
4 (a)
Explain the method proposed by Nyquist to resolve the difficulty of ISI using
duobinary pulse.
7 M
4 (b) (i)
Draw a code tree for the convolutional coder having:
Constraint length = 3, v1 = s1 +s2 +s3 & v2 = s1 +s3 .
Where si = ith stage of shift register and vi = ith modulo-2 adder output.
4 M
4 (b) (ii)
What is Noise figure?
3 M
4 (c)
Describe digital signal transmission using Quadrature Amplitude Modulation
(QAM) using necessary diagram.
7 M
4 (d) (i)
Explain an M-ary FSK digital modulation technique in brief.
4 M
4 (d) (ii)
Explain method of generating systematic cyclic codes.
4 M
5 (a)
What is advantage of Differential Phase-Shift Keying (DPSK) over BPSK?
Explain DPSK modulation technique in detail.
7 M
5 (b)
Derive the general expression of bit error rate for Optimum Binary Receiver.
7 M
5 (c)
What is the difference between coherent and non-coherent detection techniques?
Describe non-coherent detection of FSK signal.
7 M
5 (d)
Describe frequency hopping spread spectrum (FHSS) system in detail.
7 M
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