VTU Electronics and Communication Engineering (Semester 5)
Digital Signal Processing
December 2014
Total marks: --
Total time: --
INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary


1(a) State and prove the relationship between z-transform and DFT.
6 M
1(b) Determine N point DFT of \[x(n)=cos\frac{2\pi K_{0}n}{N},0\leq K\leq N-1\]
6 M
1(c) Find the IDFT of x(k) = {255, 48.63 + j166.05,-51+j102, -78.63+j46.05, -85, -78.63-j46.05,-51-j102, 48.63-166j}.
8 M

2(a) State and prove the relationship between z-t and prove the following properties :
i) Symmetry property
ii) Parseval's theorem
8 M
2(b) Prove :i) Symmetry and ii) Periodicity property of a twiddle factor.
8 M
2(c) Find the output y(n) of a filter whose impulse response is h (n) -{1,2,3,4} and the input signal to the filter is x(n) - {1,2,1,-1,3,0,5,6,2,-2,-5,6,7,1,2,0,1} using overlap add method [Use 6 point circular convolution.]
8 M

3(a) Determine y(n)\[x_{1}\circledast x_{2}(n),-n+1,0\leq n\leq 5\ and \ x_{2}(n)=cos\pi0\ n\leqn\leq 5 \] Using stockhalm's method.
10 M
3(b) Develop DIT FFT algorithm and write signal flow graph for N=8.
8 M
3(c) Explain in-place computation of FET.
2 M

4(a) Explain bit reversal property used in FFT algorithm for N = 16
3 M
4(b) Develop DIT - FFT algorithm for N = 9.
7 M
4(c) Find IDFT of x(k) -{36,-4+j9.7,-4+j4,-4+j1.7,-4,-4-j1.7,-4-j4,-4-j9.7}. Using DIF FFT algorithm.Show clearly all the intermediate results.
10 M

5(a) Design a Chebyshev filter to meet the following specifications :
i) Pass band ripple \[\leq \] db
ii) Stop band attenuation \[\geq \] 20 db
iii) Pass band edge : 1 rad/sec
iv) stop band edge : 1;3 rad/sec
10 M
5(b) Distinguish between IIR and FIR filters.
4 M
5(c) Derive an expression for order of a a low pass Butterworth filter.
6 M

6(a) Realize FIR linear phase filter for N to be even.
8 M
6(b) Evaluate the impulse response for input x(n) \[^{-}\delta (n)\] of three stage lattice structure having coefficients \[K_{1}=0.65,K_{2}=-0.34\ and \ K_{3}- 0.8.\] Also draw its direct form - I structure.
12 M

7(a) Explain how an analog filter is mapped on to digital filter using impulse invariance method. What are the limitations of the method?
10 M
7(b) Obtain direct form - I and lattices structure for the system described by the difference equation[y(n)=x(n)+frac{2}{5} imes(n-2)+frac{1}{3}x(n-3).]
10 M

8(a) for the desired frequency response
\[H(\omega )=\left\{\begin{matrix} e^{j3\omega } -\frac{3\pi }{4}& < \omega < \frac{3\pi }{4}\\0,&\frac{3\pi }{4} < |\omega |< \pi \\ & \end{matrix}\right.\]
Find H(\omega\] for N = 7 using Hanning window.
10 M
8(b) Show that for \[\beta |]- 0,Kaiser window becomes a rectangular window.
5 M
8(c) Mention few advantages and disadvantages of windowing technique.
5 M



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