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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) Define signal and system with example. And briefly explain operations performed on independent variable of the signal.
6 M
1 (b) Determine whether the following signal is energy signal or power signal and calculate its energy of power x(t)=rect(tto)cosωot.
4 M
1 (c) Find the whether the following system is stable, memory less, linear and time invariant? y(t)=sin[x(t+2)]
4 M
1 (d) Two signals x(t) and g(t) as shown in Fig Q1(d). Express the signals x(t) in terms of g(t).

Fig.1 d (i)
 

Fig. 1 d (ii)

6 M

2 (a) Given the signal x(t) as shown in Fig Q2(a). Sketch the following: i) x(2t+3)ii) x(122)

4 M
2 (b) For a DT LTI system to be stable show that SΔ=k=+k=|h(K)|<
5 M
2 (c) Two discrete time LTI systems are connected in cascade as shown in Fig Q2(c). Determine the unit sample response of this cascade connection.

6 M
2 (d) Find convolution of 2 finite duration sequences,
h(n)=anu(n) for all n and
x(n)=bnu(n) for all n
i) when a?b
ii) when a=b
5 M

3 (a) Determine the LTI system characterized by impulse response. i) h(n)=n(12)nu(n)ii)h(t)=etu(t+100) Stable and causal.
6 M
3 (b) Find the forced response of the following system; y(n)14y(n1)18y(n2)=x(n)+x(n1) for x(n)=(18)nu(n)
8 M
3 (c) Draw direct form II implementation for the system described by the following equation and indicate number of delay elements, adders, multipliers.
y(n)-0.25y(n-1)-0.125y(n-2)-x(n)-x(n-2)=0
6 M

4 (a) Prove the following properties of DTFS:
i) Convolution in time ii) Modulation theorem
6 M
4 (b) Determine the complex exponential Fourier series for periodic rectangular pulse train shown in Fig Q4(b). Plot its magnitude and phase spectrum.

8 M
4 (c) Determine the DTFS representation for the signal x(n)=\cos \left ( \dfrac {n\pi}{3} Plot the spectrum of x(n).
6 M

5 (a) State and prove the following properties of DTFT:
(i) Parseval's theorem ii) Linearity
6 M
5 (b) Find the DTFT on the signals shown, i) x(n)=(14)nu(n+4)ii)x(n)=u(n)
8 M
5 (c) Find the inverse Fourier transform of the rectangular shown below

6 M

6 (a) Consider the continuous time LTI system described by, ddty(t)+2y(t)=x(t) Using FT, find the output y(t) to each of the following input signals.
i) x(t)=e-tu(t)
ii) x(t)=u(t)
8 M
6 (b) Find the Nyquist rate and Nyquist interval for each of the following signals:
i) x(t)=sin c2 (200t)
ii) x(t)=2 sin c(50t) sin(5000?t)
6 M
6 (c) An LTI system is described by H(f)=42+j2πf find its response y(t) if the input is x(t)=u(t).
6 M

7 (a) Define ROC and list its properties.
4 M
7 (b) State and prove time reversal property of z-transform.
4 M
7 (c) Determine the inverse z-transform of x(z)=1(1+z1)(1z1)2;ROC;|z|>1
6 M
7 (d) Determine z-transform and ROC of x(n)=(13)nsin(π4n)u(n)
6 M

8 (a) A causal, stable discrete time system is defined by \[ y(n)= \dfrac {5}{6} y(n-1)-\dfrac {1}{6}y(n-2)+x(n)-2x(n-1) Determine :
i) System function H(z) and magnitude response at zero frequency
ii) Impulse response of the system.
iii) Output y(n) for x(n)=?(n)- 1/3 ?(n-1)
12 M
8 (b) Solve the following difference equation for the given initial conditions and input, y(n)19y(n2)=x(n1)with y(1)=0,y(2)=1 and x(n)=3u(n)
8 M



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