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AC Questions Paper

This document contains a question paper for a Digital Signal Processing exam with 10 questions divided into 2 parts - Part A and Part B. Part A contains 10 short answer questions covering topics like LTI systems, frequency response, discrete Fourier series, circular convolution, bilinear transformation, stability of IIR filters, disadvantages of Fourier series, characteristics of windows, need for anti-imaging filters, and effects of deadbands. Part B contains 5 multi-part questions involving topics like analysis of systems, z-transforms, filter design using bilinear transformation, impulse invariance, DFT, FFT, Hilbert transforms, sampling rate conversion, and finite word length effects. Students are required to answer 1 full question from each of the 5 units

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123 views2 pages

AC Questions Paper

This document contains a question paper for a Digital Signal Processing exam with 10 questions divided into 2 parts - Part A and Part B. Part A contains 10 short answer questions covering topics like LTI systems, frequency response, discrete Fourier series, circular convolution, bilinear transformation, stability of IIR filters, disadvantages of Fourier series, characteristics of windows, need for anti-imaging filters, and effects of deadbands. Part B contains 5 multi-part questions involving topics like analysis of systems, z-transforms, filter design using bilinear transformation, impulse invariance, DFT, FFT, Hilbert transforms, sampling rate conversion, and finite word length effects. Students are required to answer 1 full question from each of the 5 units

Uploaded by

nareddy vinay kumar reddy
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© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as PDF, TXT or read online on Scribd
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Code No: 126EK

R13
JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD
B. Tech III Year II Semester Examinations, May - 2017
DIGITAL SIGNAL PROCESSING
(Common to ECE, EIE)
Time: 3 hours Max. Marks: 75

Note: This question paper contains two parts A and B.


Part A is compulsory which carries 25 marks. Answer all questions in Part A. Part B
consists of 5 Units. Answer any one full question from each unit. Each question carries
10 marks and may have a, b, c as sub questions.

PART - A
(25 Marks)

1.a) What is an LTI system? [2]


b) Define the frequency response of a discrete-time system. [3]
c) Define discrete Fourier series. [2]
d) Obtain the circular convolution of the sequence x(n)={1,2,1}; h(n)={1,-2,2}. [3]
e) What is meant by bilinear transformation? [2]
f) Prove that physically realizable and stable IIR filters cannot have linear phase. [3]
g) What are the disadvantages of Fourier Series Method? [2]
h) What is the desirable characteristics of the Window? [3]
i) What is the need for anti-imaging filter after up sampling a signal? [2]
j) What are the effects of Dead band? [3]

PART - B
(50 Marks)

2.a) Determine whether each of the following systems defined below is (i) Causal (ii) Linear
(iii) Dynamic (iv) Time invariant (v) Stable.
n
(I) y (n)  e
k  n 3
x(k )
(II) y(n)  x(n  2)

b) For each impulse response listed below, determine whether the corresponding system is
(i) causal (ii) stable. [5+5]
(I) h(n)  2 u(n)
n
(II) h(n)  e u(n  1)
2n

OR
3.a) If x(n) is a causal sequence, find the z- transform of the following sequences.
(i) x(n)  nu(n) (b) x(n)  nu(n  1)
b) Find the response of y(n)  y(n  1)  2 y(n  2)  u(n  1)  2u(n  2) due to
y(1)  0.5; y(2)  0.25 . [5+5]

4.a) Compute the DFT of the square-wave sequence


 N
 1 0  n  2 1
x ( n)   Where N is even.
N
 1  n  N 1
 2 www.ManaResults.co.in n
1
b) Find 4-point DFT of the following sequence x(n)    . [5+5]
4
OR
5.a) An 8-point sequence is given by x(n)  2,2,2,2,1,1,1,1 .Compute 8-point DFT of x(n)
by radix-2 DIT-FFT.
n
b) Compute the DFT of the sequence x(n)  cos , where N=4 using DIF FFT
2
algorithm. [5+5]

6. Design a chebyshev filter for the following specifications using (a) bilinear
transformation. (b) Impulse Invariance method. [10]
 
0.8  H e  1 0  w  0.2
jw

H e   0.2
jw
0.6  w  
OR
7.a) Design a lowpass filter that will operate on the sampled analog data such that the cutoff
frequency is 200Hz and at 400Hz, the attenuation is atleast 20dB with a monotonic
1
shape past 200Hz. Take T = secs and use normalized lowpass filter.
2000
b) A third-order Butterworth low pass filter has the transfer function:
1
H ( s)  . Design H(z) using Impulse Invariance method. [5+5]
( s  1)( s 2  s  1)

8.a) Design an ideal Hilbert transformer having frequency response


 j for    w  0
 
H e jw   ; using rectangular window.
 j for 0  w  
b) For the desired frequency response given by
  j 3w 3
e , w 
H d ( w)   4
3
 0,  w 
 4
Find H(ω) for N=7 using Hamming window for truncating hd(n). [5+5]
OR
9.a) Design an FIR digital filter H(z) that when used in the prefilter A/D -H(z) – D/A
structure will satisfy the following equivalent analog specifications.
i) Low pass filter with -1dB cutoff at 100π rad/sec.
ii) Stop band attenuation of 35dB or greater at 1000π rad/sec.
iii) Sampling rate of 2000 samples/sec.
iv) The phase must be linear.
b) Draw the magnitude response, W ( ) versus ω, for nine-term windows of the following
i) Rectangular window ii) Hanning window. [6+4]

10.a) Explain the application of sampling rate conversion in subband coding.


b) Discuss in detail the down sampling with a neat diagram. [5+5]
OR
11.a) Explain the multistage implementation of sampling rate conversion.
www.ManaResults.co.in
b) Explain the finite word length effects in digital filter. [5+5]

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