Anna University Questions  CS9351 Digital Signal Processing April may 2014, Computer Science and Engineering (CSE), Sixth semester, regulation 2008
Exam

B.E/B.Tech. (Full
Time) DEGREE END SEMESTER EXAMINATIONS

Academic
Year

April May 2014

Subject
Code

CS9351 
Subject
Name

Digital Signal Processing 
Branch

Computer Science and Engineering

Semester

Sixth Semester

Regulation

2008

B.E
/ B.Tech. (Full Time) DEGREE END SEMESTER EXAMINATIONS, APRIL / MAY 2014
Computer Science
and Engineering
Sixth Semester
CS9351
DIGITAL SIGNAL PROCESSING
(Regulations 2008)
Time : 3 Hours Answer A L L Questions Max. Marks 100
PARTA
(10 x 2 = 20 Marks)
1. Check whether y(n) = e^{x(n)}
is LTIS or not.
2. Compute the circular convolution of
x(n) = {2,1,0,1} and y(n) = {1,2,1,2}.
3. Prove that the multiplication of
DFTs of two sequences is equivalent to the circular convolution of the two
sequences in the time domain.
4. Does FFT algorithm reduce the
number of multiplications required to compute a single point of the DFT?
Justify your answer.
5. Give the analog transformation for
band pass filter as well as band stop filter.
6. Explain the realization of linear
phase FIR system.
7. How to prevent errors due to
overflow of signals?
8. What is the impact of using each
bit in the A/D conversion in the signaltonoise power ratio?
9. What are the steps involved in
speech compression?
10. How does adaptive filter help in
channel equalization? Illustrate with neat diagram.
PartB
(5* 16 = 80 Marks)
11. i. Determine the response, y(n) of
the following system:
h (n) = u(n+4)  u(n3), x(n) = u(n+2)
 u(n2)  5(n3). (5)
ii. Determine the crosscorrelation
between x(n) and y(n) in (i). (5)
ii. Determine the Ztransform and ROC
for the following sequence (6)
x(n) = 3^{n}u(n+2) 4^{n}u(n2)
12. a. i.Compute the FFT using DIF
algorithm for the sequence given by
x(n) = 2^{n}, N=8. (10)
ii. An FIR filter has the unit impulse
response sequence h(n)={3,2,l}. Determine the output sequence in response to
x(n)= {2,4,0,1,2,3,1,1,2,3,2} using overlap save method. (6)
(OR)
b. i. Compute the inverse FFT using
DIT algorithm for X(k) = {20, 5.828j2.414, 0, 0.172j0.414, 0,
0.172+j0.414, 0, 5.828+j2.414}. (10)
ii. An FIR filter has the unit impulse
response sequence h(n)={ 1,1,1}.
Determine the output sequence in
response to x(n)= {2,1,0,2,2,3,1,0,1,2,2} using overlap add method. (6)
13. a. Design a low pass Butterworth
filter for the following specification: (16)
Passband gain: 0.8
Passband edge: 
0.27π rad/ sec
Stop band
attenuation : 0.2
Stop band edge :
0.6π rad / sec
Use bilinear transformation technique
with T = 1 sec and realize the designed filter in parallel form.
(OR)
b. Design a low pass Chebyshev filter
for the following specification. (16)
Passband gain:
2.5dB
Passband edge: 200
rad/ sec
Stop band
attenuation:  25dB
Stop band edge :
300 rad / sec
Convert it into a HPF with pass band
edge frequency and realize in Direct form II.
14. a. i. Design a FIR low pass filter
for the following specification and realize it using cascade form.
H_{d}(ω) = e^{j4ω}  ω
 ≤ π/4
= 0 (π/4)
≤ ω ≤ π
Use Harming window for terminating the
desired frequency response. (12)
ii. Explain the quantisation effects
in Analog to Digital conversion. (4)
(OR)
b. i. Design a FIR low pass filter for
the following specification using Frequency sampling method and realize it
using Direct form structure. (12)
Pass band edge: 400
Hz
Stop band begins
at: 800 Hz
Sampling frequency:
4000 Hz
Filter Length: 10
ii. Explain Limit cycle oscillations
and product quantisation. (4)
15. a. Define Multirate signal
processing. Explain decimation and interpolation in detail with necessary
diagrams. (16)
(OR)
b. Explain various Image enhancement
techniques in spatial as well as frequency domain. (16)
3
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