C
HAPTER
2
1.
The value of the integral
( )cos
tt
d
t
δ
∞
−∞
∫
is equal to
(a)
zero
(b)
one
(c)
infinity
(d)
undefined
2.
The solution of the integral
2
3
1
(3
)
(
2
)
d
t
−
++
∫
is
(a)
–5
(b)
–2
(c)
zero
(d)
11
3.
An impulse function consists of
(a)
the entire frequency range with the same relative phase
(b)
finite bandwidth with linear phase variations
(c)
pure d.c.
(d)
large d.c. along with weak harmonics
4.
Sinusoidal function is used as the basic function in electrical communication because,
(a)
convenience
(b)
the response of a linear system to a sine
wave is still a sine wave
(c)
both a and b
(d)
none
5.
A sine wave generator starts at
t
= 0. It consists of
(a)
a pure sine wave
(b)
a pure cosine wave
(c)
both
(d)
sine wave plus other frequencies
6.
Which one is not a reason of distortion in communication system?
(a)
insufficient channel bandwidth
(b)
random variation in channel
(c)
external interference
(d)
none
7.
The Fourier transform of a voltage signal
x
(
t
) is
X
(
f
). The unit of 
X
(
f
) is
(a)
volt
(b)
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 Fall '08
 PingLi
 Frequency, Energy density, Sine wave

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