VTU Electrical and Electronic Engineering (Semester 5)
Signals and Systems
December 2016
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


1(a) Explain about power and energy signal with example. Determine whether signal given in Fig. Q1(a) is power of energy signal, find correseponding value.
6 M
1(b) Findout the even and odd component of the following signals i) x(t) = cost+sint+sint cost
ii) x(t) = 1+t+3t2+6t3+9t4
iii) x(t) = 1+t cost + t2 sint+ t3 sint cost.
6 M
1(c) For the given signal x(t) shown in FigQ1(c) sketch and label i) x(0.5t)
ii) x(t+3)
iii) x(3t+2)
iv) x(-3(t-1))
!mage
8 M

2(a) Impulse response of a system is given by \( x\left [ n \right ] =\left\{\begin{matrix} 1& &n=0 \\ \frac{1}{2}& &n=1 \\ 0& & \text{otherwise} \end{matrix}\right. \)/
Input for the given system is \( x\left [ n \right ] = \left\{\begin{matrix} 2& &n=0 \\ 4& &n=1 \\ {-2}& &n=2 \\ 0& &\text{otherwise} \end{matrix}\right. \)/ Findout the y[n] of the system.
6 M
2(b) Given inpulse response of the system\( h[n]=\left [ \frac{1}{2} \right ]^n u\left [ n-2 \right ]. \)/ Find out step response of the system.
8 M
2(c) Draw direct from - I and direct from - II implementation for the following difference equation. \(y\left [ n \right ]+\frac{1}{4}y\left [ n-1 \right ]-\frac{1}{8}y\left [ n-2 \right ]=2x\left [ n \right ]+3x\left [ n-1 \right ] \)/
6 M

3(a) Obtain the convolution integral for a system with input x(t) and inpulse response h(t), as shown in Fig Q3(a).
!mage
8 M
3(b) For the given impulse response determine whether system is memory less, stable and cause justify your answer. h[n] = [2]nu[-n].
4 M
3(c) Find out the complete solution for the system described by the following differential equations.\( \frac{d^2y(t)}{dt^2}+5\frac{d}{dt}y(t)+6y(t)=x(t) \)/, Where x(t) = e4u(t) With initial conditions \( y(0)= -\frac{1}{2},\frac{d}{dt}y(t)\bigg|_{t=0}=\frac{1}{2} \)/
8 M

4(a) Determine the Fourier series representation of the square wave shown in FigQ4(a)
!mage
8 M
4(b) Determine the discrete Fourier series representation for the following signal.\( x\left [ n \right ]=\cos \frac{\pi }{3}n+\sin \frac{\pi }{4}n \)/
8 M
4(c) State and prove the time shift and frequency shift property of Fourier series.
6 M

5(a) Using the properties of Fourier Transform find out Fourier transform of the following signals.
i) x(t) = sin(πt)e-2tu(t)
ii) x(t) = e-3(t-2)
12 M
5(b) Obtain the Fourier Transform of the following signals. i) x(t) =u(t)
ii) x(t)=e-utu(t)
iii) \( \begin{matrix} x(t)=1 & -0.5\leq t\leq 0.5\\ \ \ =0 & \text{elsewhere}. \end{matrix} \)/
8 M

6(a) Find DTFT of the following signal \[i)x\left [ n \right ]=\left [ \frac{1}{2} \right ]^{n+2} u\left [ n \right ] \ \ ii) x\left [ n \right ] =n\left [ \frac{1}{2} \right ]^{2n} u\left [ n \right ]\ \ iii) x\left [ n \right ]= -\left [ \frac{1}{2} \right ]^n u\left (- n-1 \right )\]
12 M
6(b) An LTI causal system is having a frequency response as \( H\left ( e^{j\Omega } \right )=\frac{e^{j\Omega }}{1+\cos \Omega } \)/. Obtain linear constant difference equation of the system.
8 M

7(a) Obtain z transform and the ROC and location of poles and zero's of x(z) for the following x[n]. \[i)x[n]=\left [ \frac{1}{2} \right ]^n u[n]+\left ( -\frac{1}{3} \right )^n u[n] \ \ ii)x[n]=-\left ( \frac{3}{4} \right )^n u(-n-1)+\left ( -\frac{1}{3} \right )^n u[n]\]
10 M
7(b) Obtain inverse 'z' transform of the given(z) using partial fraction expansion \(x(z)=\frac{1-z^{-1}+z^{-2}}{\left ( 1-\frac{1}{2^{z-1}} \right )\left ( 1-2z^{-1} \right )\left ( 1-z^{-1} \right )} \)/ i) with ROC 1<|z|<2
ii) with ROC |z|<&fraction;1and2
10 M

8(a) Use convolution property of 'z' transform to obtain x(z) for the given x(n) \[x(n)= u(n-2)*\left ( \frac{2}{3} \right )^n u(n)\]
6 M
8(b) Obtain inverse 'z' transform of \( x(z)=\frac{2+z^{-1}}{1-\frac{1}{2}^{z-1}} \)/ with ROC |z|>\[\frac{1}{2}\]
6 M
8(c) Solve the following linear constant coefficient difference equation using z transform method \( y[n]-\frac{1}{2}y[n-1]=x[n] \)/ with given input \( x[n]=\left ( \frac{1}{3} \right )^n\)/ and initial condition y[-1]=1
8 M



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