MU Electronics Engineering (Semester 6)
Discrete Time Signal & System
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


Answer any four:
1 (a) LTI system is stable if its impulse response is absolutely summable. Justify your answer.
5 M
1 (b) List the advantages/disadvantages of DSP processor w.r.t. general microprocessors.
5 M
1 (c) Write the analysis and synthesis equation for DTFT, DFT & Z- Transform.
5 M
1 (d) How many complex addition and complex multiplication required to be performed to find DFT of 256 point signal using FFT algorithm? Hence Justify advantages/disadvantages of FET algorithm.
5 M
1 (e) \[ x[n] = \{2, -1, {\underset{\uparrow}{2}}, -3\} \] Express x[n] in terms of its even and odd components.
5 M

2 (a) Write one equation for each finite and infinite duration.
i) Causal signal
ii) Anti-causal signal
iii) Two sided signal
in discrete time domain and plot the same.
10 M
2 (b) \[ H[n] = \left \{1, - \dfrac {1}{2} \right \}, \] Determine the frequency response. If H(n) is impulse response of an filter then identify the type of filter based on its passed band.
10 M

3 (a) Explain correlation property of Z-Transform. Determine the cross correlation sequence of Z-Transform. Determine the cross correlation sequence ?x1x2(1) of x1[n]={1,2,3,4} x2[n]={4, 3, 2, 1}
10 M
3 (b) A LTI system function is given as: \[ H(z) = \dfrac {3-4z^{-1}}{1-3.5 z^{-1}+1.5z^{-2}} \] Determine h(n) if
i) The system is stable
ii) The system is causal
iii) The system is anti-causal
Specify the ROC of H(z) in all cases.
10 M

4 (a) A system has unit sample response h[n] given as \[ h[n]= \dfrac {-1}{4}\delta [n+1]+ \dfrac {1}{2}\delta [n] - \dfrac {1}{4} \delta [n-1] \]
i) Is the system BIBO stable?
ii) Is the system causal?
iii) Find magnitude, plot the same (magnitude response only)
10 M
4 (b) Explain overlap add and overlap save method for filtering of long data sequences.
10 M

5 (a) Develop DIFFET algorithms for decomposing the DFT for N=6.
10 M
5 (b) x[n]={1,0,1,0,0,0,1,1} find X(k) using DIT-FFT algorithm.
10 M

6 (a) x1[n]={1,2,3,4}
x2[n]={5,6,7,8}
x3[n]={1+j, 2+6j, 3+7j, 4+8j}
Find DFT of X1(k), X2(k) & X3(k) but computing DFT only once.
10 M
6 (b) List the two properties of twidde factor. Justify these properties using appropriate example with N=8 (min data length).
10 M

Attempt any four:
7 (a) Compare IIR and FIR system.
5 M
7 (b) Application of DSP processors.
5 M
7 (c) Geortzel Algorithm
5 M
7 (d) Mapping between s-plane and z-plane for stable systems.
5 M
7 (e) System classification.
5 M



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