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1.
Statement for Linked Answer Questions :
A 30-Volts battery with zero source resistance is connected to a coaxial line of characteristic impedance of 50 Ohms at t = 0 second terminated in an unknown resistive load. The line length is that it takes 400µs for an electromagnetic wave to travel from source end to load end and vice-versa. At t = 400μs, the voltage at the load end is found to be 40 Volts.[1] The load resistance is [2 marks]
(A) 25 Ohms
(B) 50 Ohms
(C) 75 Ohms
(D) 100 Ohms[2] The steady-state current through the load resistance is: [2 marks]
(A) 1.2 Amps
(B) 0.3 Amps
(C) 0.6 Amps
(D) 0.4 Ampsasked in Electronics and Communication Engineering, 2006
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2.
Statement for Linked Answer Questions :
Consider a unity-gain feedback control system whose open-loop transfer function is:
G(s) = (as+1)/s2
[1] The value of “a” so that the system has a phase margin equal to π/4 is approximately equal to [2 marks]
(A) 2.40
(B) 1.40
(C) 0.84
(D) 0.74[2] With the value of “a” set for a phase-margin of π/4, the value of unit-impulse response of the open-loop system at t = 1 second is equal to [2 marks]
(A) 3.40
(B) 2.40
(C) 1.84
(D) 1.74asked in Electronics and Communication Engineering, 2006
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3.
Statement for Linked Answer Questions ::
Consider the following Amplitude Modulated (AM) signal, where fm < B.
XAM(t) = 10 (1 + 0.5 sin2πfmt) cos2πfct[1] The average side band power for the AM signal given above is:
[2 marks]
(A) 25
(B) 12.5
(C) 6.25
(D) 3.125[2] The AM signal gets added to a noise with Power Spectral Density Sn(f) given in the figure below. The ratio of average sideband power to mean noise power would be: 
[2 marks]
(A) 25/8NoB
(B) 25/4NoB
(C) 25/2NoB
(D) 25/NoB
asked in Electronics and Communication Engineering, 2006
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4.
Statement for Linked Answer Questions::
The following two questions refer to wide sense stationary stochastic processes.[1] It is desired to generate a stochastic process (as voltage process) with power spectral density.
s(ω) = 16/(16+ω2)
By driving a Linear-Time-Invariant system by zero mean white noise (as voltage process) with power spectral density being constant equal to 1. The system which can perform the desired task could be: [2 marks]
(A) first order lowpass R-L filter
(B) first order highpass R-c filter
(C) tuned L-C filter
(D) series R-L-C filter
[2] The parameters of the system obtained in above question would be
[2 marks]
(A) first order R-L lowpass filter would have R = 4Ω, L = 4H
(B) first order R-C highpass filter would have R = 4Ω, C = 0.25F
(C) tuned L-C filter would have L = 4H, C = 4F
(D) series R-L-C lowpass filter would have R = 1Ω,, L = 4H, C = 4Fasked in Electronics and Communication Engineering, 2006
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5.
Statement for Linked Answer Questions:
A regulated power supply, shown in figure below, has an unregulated input (UR) of 15 Volts and generates a regulated output Vout. Use the component values shown in the figure.
In the figure above, the ground has been shown by the symbol ∇.[1] The power dissipation across the transistor Q1 shown in the figure is:
[2 marks]
(A) 4.8 Watts
(B) 5.0 Watts
(C) 5.4 Watts
(D) 6.0 Watts[2] If the unregulated voltage increases by 20%, the power dissipation across the transistor Q1 [2 marks]
(A) increases by 20%
(B) increases by 50%
(C) remains unchanged
(D) decreases by 20%asked in Electronics and Communication Engineering, 2006
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6.
Let g (t) = p (t) * p (t) ,where * denotes convolution and p (t) = u (t)−u(t−1) with u (t) being the unit step function.
[1] The impulse response of filter matched to the signal s (t) = g(t)−δ(t − 2)*g(t) is given as: [2 marks]
(A) s (1 − t )
(B) −s (1 − t )
(C) −s (t )
(D) s (t )[2] An Amplitude Modulated signal is given as
XAM(t) = 100 (p(t)+0.5g(t)) cosωct
in the interval 0 ≤ t ≤ 1. One set of possible values of the modulating signal and modulation index would be [2 marks]
(A) t,0.5
(B) t,1.0
(C) t,2.0
(D) t2 ,0.5
asked in Electronics and Communication Engineering, 2006
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