DIGITAL SIGNAL PROCESSING – Nov 2011 Anna University Previous year Model Question Paper

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B.E./B.Tech. DEGREE EXAMINATION, NOVEMBER/DECEMBER 2011.
Seventh Semester www.2webworld.com
Computer Science and Engineering
CS 2403 — DIGITAL SIGNAL PROCESSING
(Common to Fifth Semester Information Technology)
(Regulation 2008)
Time : Three hours Maximum : 100 marks
Answer ALL questions. www.2webworld.com
PART A — (10 × 2 = 20 marks)
1. Define and express the transfer function of Nth order LTI system.
2. Compare linear convolution and circular convolution.
3. What is the relation between DFT and Z-Transform?
4. What is phase factor or twiddle factor?
5. Sketch the various tolerance limits to approximate an ideal lowpass and
highpass filter. www.2webworld.com
6. What is the importance of poles in filter design?
7. What is frequency warping?
8. What is Butterworth approximation?
9. List various voice compression and coding techniques.
10. What are the various enhancement techniques in image processing?
PART B — (5 × 16 = 80 marks)
11. (a) (i) Find the inverse Z-Transform of
using www.2webworld.com
(1) Residue method and
(2) Convolution method. (8)
(ii) State and prove circular convolution. (8)
Or www.2webworld.com
(b) LTI system is described by the difference equation
y(n ) = a y(n ?1) + b x (n ). Find the impulse response, magnitude
function and phase function. Solve b, if H (w) = 1 . Sketch the
magnitude and phase response for a = 0.6. (16)
12. (a) (i) Evaluate the 8-point for the following sequences using DIT-FFT
algorithm (8)
( ) www.2webworld.com
(ii) Calculate the percentage of saving in calculations in a 1024-
point radix -2 FFT, when compared to direct DFT. (8)
Or www.2webworld.com
(b) Determine the response of LTI system when the input sequence
x (n ) = {?1, 1, 2, 1, ?1 } by radix 2 DIT FFT. The impulse response of the
system is h(n ) = {?1, 1, ?1, 1}. (16)
13. (a) The specification of the desired lowpass filter is
( )
Design a Butterworth digital filter using bilinear transformation. (16)
Or www.2webworld.com
(b) The specification of the desired low pass filter is
( ) www.2webworld.com
Design a Chebyshev digital filter using impulse invariant
transformation. (16)
14. (a) (i) Design a single tier notch filter to reject frequencies in the range
1 to 2 rad/sec using rectangular window with N = 7 . (8)
(ii) Compare Hamming window and Kaiser window. (8)
Or www.2webworld.com
(b) (i) Explain the characteristics of a limit cycle oscillation with
respect to the system described by the equation
y(n ) = 0.95 y(n ?1) + x (n ). Determine the dead band of the filter. (8)
(ii) Explain Gibb’s phenomenon (or Gibb’s oscillation). (8)
15. (a) Explain the methods of speech analysis and synthesis in detail. (16)
Or www.2webworld.com
(b) Explain how image enhancement restoration and coding can be done
using signal processing. (16)