STUPIDSID
1 (a)
Find the Fourier transform of i) u(t) , ii) δ(2πf)
6 M
1 (b)
Draw block diagram of superheterodyne receiver and explain function of each
Block.
6 M
1 (c)
Why we need modulation?
2 M
2 (a)
An AM signal is represented by the expression
V(t)=5[1+0.6cos(6280t)]sin(2π×104t) volts.
Find the
V(t)=5[1+0.6cos(6280t)]sin(2π×104t) volts.
Find the
7 M
2 (b)
Calculate the percentage power saving when the carrier and one of the sidebands
are suppressed in an AM wave modulated to a depth of
(a) 100 percent, and
(b) 50 percent.
(a) 100 percent, and
(b) 50 percent.
7 M
2 (c)
An angle-modulation signal with carrier frequency ωc=2π×105 is described by the equation ∅EM=10cos (ωct+ 5sin 3000t+10 sin 2000 πt)
(a) Find the Power of the modulated signal.
(b) Find the frequency deviation Δf.
(c) Find the Deviation ratio β
(d) Estimate the bandwidth of ∅EM(t).
(a) Find the Power of the modulated signal.
(b) Find the frequency deviation Δf.
(c) Find the Deviation ratio β
(d) Estimate the bandwidth of ∅EM(t).
7 M
3 (a)
For series tuned circuit derive expression for resonance frequency, series Q-
factor and the -3dB bandwidth. Give the uses of this circuit in communication.
7 M
3 (b)
Define Shot Noise and Partition Noise.
A Mixer stage has a noise figure of 20 dB and it is preceded by an amplifier with
a noise figure of 9dB. Calculate the overall noise figure referred to the input.
7 M
3 (c)
Define the Noise, Noise factor, Equivalent noise temperature and importance of
S/N ratio in communication.
7 M
3 (d)
Discus the Phasing Method for SSB Generation.
7 M
4 (a)
Explain the working of diode envelope detector and give the remedies for
Diagonal Peak Clipping.
7 M
4 (b)
What is Pre-emphasis? Why it is used? Sketch a typical pre-emphasis circuit and
explain why de-emphasis must be used also.
7 M
4 (c)
Write a short note on "Automatic Gain Control" in superheterodyne receiver.
7 M
4 (d)
List the various angle modulation detectors methods. Discuss any one in detail.
7 M
5 (a)
State and prove the following Fourier Transform properties
i) Time-scaling Property,
ii) Frequency-shifting Property.
i) Time-scaling Property,
ii) Frequency-shifting Property.
7 M
5 (b)
Explain phase locked loop and vestigial sideband transmission.
7 M
5 (c)
Estimate the essential bandwidth W (in rad/s) of the signal e-at u(t) if the essential
band is required to contain 95% of the signal energy.
7 M
5 (d)
Find the Friiss formula (equivalent noise factor) for amplifiers connected in
Cascade.
7 M
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