Indian Institute of Technology Kharagpur (IIT-K) 2006 M.E Electronics and Telecommunications Gate ece - Question Paper
Wednesday, 23 January 2013 01:55Web
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(B) statistically independent
(C) uncorrelated
(D) orthogonal
50. A source generates 3 symbols with probabilities 0.25, 0.25, 0.50 at a rate of
3000 symbols per second. Assuming independent generation of symbols, the most efficient
source encoder would have avg. bit rate as
(A) 6000 bits/sec
(B) 4500 bits/sec
(C) 3000 bits/sec
(D) 1500 bits/sec
51. The diagonal clipping in Amplitude Demodulation (using envelope detector) can be avoided
if RC time-constant of the envelope detector satisfies the subsequent condition, (here W is
message bandwidth and a is carrier frequency both in rad/sec)
(A) RC<--w
(B) RC>--w
(C) RC<—--o)c
(D) RC>—-o)c
52. A message signal with bandwidth 10 kHz is Lower-Side Band SSB modulated with carrier
frequency t = 1O Hz: The resulting signal is then passed through a
Narrow-Band Frequency Modulator with carrier frequency two = iO Hz.
The bandwidth of the output would be:
(A) 4x104 Hz
(B) 2x106 Hz
(C) 2x109 Hz
(D) 2x101° Hz
53. A medium of relative permittivity two = two forms an interface with free-space. A point source
of electromagnetic energy is located in the medium at a depth of one meter from the interface.
Due to the total internal reflection, the transmitted beam has a circular cross-section over the
interface. The area of the beam cross- part at the interface is provided by
(A) 2,rm2
(B) r2m2
(C) -m2
(D) rm2
54. A medium is divided into regions I and II about x = 0 plane, as shown in the figure beneath.
An electromagnetic wave with electric field E1 = 4a + 3a + 5a is incident normally on the
interface form region-I. The electric field E2 in region-Il at the interface is:
Region I Region II
= °P1 = = °P2 =
E1 E
x
(A) E2=E1
(B) 4a +0.75a —1.25a
(C) 3a+3a+5a
(D) —3a + 3a + 5a
54. A rectangular waveguide having TE10 mode as dominant mode is having a cutoff
frequency of 18-GHz for the TE30 mode. The inner broad-wall dimension of the rectangular
waveguide is:
(A) 5— cms
(B) five cms
(C) eight cms
(D) 10 cms
55. A mast antenna consisting of a 50 meter long vertical conductor operates over a perfectly
conducting ground plane. It is base-fed at a frequency of 600 kHz. The radiation resistance of
the antenna in Ohms is:
(A)
(B)
(C)
(D) 20,r2
Common Data Questions:
Common Data for ques. 71, 72, 73:
In the transistor amplifier circuit shown in the subsequent parameters:
I3DC = 60, “BE = 0. 7V, hie — 00, hfe °° The capacitance Ccan be presumed to be infinite.
5.3K
figure below, the transistor has the
1 2V
In the figure above, the ground has been shown by the symbol V
71. Under the DC conditions, the collector-to-emitter voltage drop is:
(A) 4.8 Volts
(B) 5.3 Volts
(C) 6.0 Volts
(D) 6.6 Volts
72. If I3DC is increased by 10°h, the collector-to-emitter voltage drop
(A) increases by less than or equal to 10%
(B) reduces by less than or equal to 10%
(C) increases by more than 10%
(D) reduces by more than 10°h
73. The small-signal gain of the amplifier v/v is:
(A) -10
(B) -5.3
(C) 5.3
(D) 10
Common Data for ques. 74, 75:
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
74. The impulse response of filter matched to the signal s (t) = g (t) — —2) * g (t) is
provided as:
(A) s(1—t)
(B) —s (1 — t) T EForum
(C) —s(t)
(D) s(t)
75. An Amplitude Modulated signal is provided as
XAM (t) = 100(p(t)+0.5g(t))cosat
in the interval 0 < t < 1. 1 set of possible values of the modulating signal and modulation
index would be
(A) t,O.5
(B) t,1.O
(C) t,2.O
(D) t2,0.5
Linked ans Questions: Q.76 to Q.85 Carry 2 Marks every.
Statement for Linked ans ques. 76 & 77:
A regulated power supply, shown in figure below, has an unregulated input (UR) of 15 Volts
and generates a regulated output Use the component values shown in the
figure.
In the figure above, the ground has been shown by the symbol V
76. The power dissipation across the transistor Qi shown in the figure is:
(A) 4.8 Watts
(B) 5.0 Watts
(C) 5.4 Watts
(D) 6.0 Watts
77. If the unregulated voltage increases by 20%, the power dissipation across the
transistor Qi
(A) increases by 20°h
(B) increases by 50°h
(C) remains unchanged
(D) reduces by 20°h
Statement for Linked ans ques. 78 & 79:
The subsequent 2 ques. refer to wide sense stationary stochastic processes
78. It is desired to generate a stochastic process (as voltage process) with power spectral
density 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:
(A) 1st order lowpass R-L filter
(B)
(C)
(D)
Statement for Linked ans ques. 80 & 81:
Consider the subsequent Amplitude Modulated (AM) signal, where m
avg. side band power fo tie AM signal provided above is:
81. The AM signal gets added to a noise with Power Spectral Density S (f)given in the figure
below. The ratio of avg. sideband power to mean noise power would be:
(A) 25
(B) 12.5
(C) 6.25
(D) 3.125
Statement for Linked ans ques. 82 & 83:
Consider a unity-gain feedback control system whose open-loop transfer function is:
first order highpass R-c filter tuned L-C filter
series R-L-C filter
82. The value of “a” so that the system has a phase margin equal to -is
approximately equal to
(A) 2.40
(B) 1.40
(C) 0.84
(D) 0.74
83. With the value of “a” set for a phase-margin of the value of unit-impulse
response of the open-loop system at t = one 2nd is equal to
(A) 3.40
(B) 2.40
(C) 1.84
(D) 1.74
Statement for Linked ans ques. 84 & 85:
A 30-Volts battery with zero source resistance is connected to a coaxial line of characteristic
impedance of 50 Ohms at t = 0 2nd terminated in an unknown resistive load. The line
length is that it takes 400 ps for an electromagnetic wave to travel from source end to load
end and vice-versa. At t = 400ps, the voltage at the load end is obtained to be 40 Volts.
84. The load resistance is
(A) 25 Ohms
(B) 50 Ohms
(C) 75 Ohms
(D) 100 Ohms
85. The steady-state current through the load resistance is:
(A) 1.2 Amps
(B) 0.3 Amps
(C) 0.6 Amps
(D) 0.4 Amps
| Earning: Approval pending. |
