Theory_Questions:
1. The Hilbert transform of a signal
g(t) is 1/πt, then what is the name
of the signal g(t)?
a. Unit Step signal
b. Impulse signal
c. Ramp signal
d. parabolic signal
Answer: [B] Impulse signal
2. Identify the Hilbert transform of
(sin t/t)?
a.(1+cos(t))/t
b. (1-cos(t))/t
c. (1+sin(t))/t
d. (1-sin(t))/t
Answer: [B] (1-cos(t))/t
3. Hilbert transform of (t/ (1+t2))
a. 1/(1+t2)
b. 1/(1-t2)
c. -1/(1+t2)
d. -1/(1+t2)
Answer: [C] -1/(1+t2)
4. Consider a signal X(t) and the
Hilbert transform of the signal X(t) is Y(t).the energy of the
signal Y(t) is “E”,then what is the energy of the signal X(t)?
a. -E
b. E/2
c. E
d. -E/2
Answer: [C] E
5. The Hilbert transform of the product
of non overlapping low-pass and high-pass signals is?
a. Multiplication of low-pass signal by
the Hilbert transform of the high-pass signal
b. Multiplication of high-pass signal
by the Hilbert transform of the low-pass signal
c. convolution of low-pass signal by
the Hilbert transform of the high-pass signal
d. Convolution of high-pass signal by
the Hilbert transform of the low-pass signal.
Answer: [A] Multiplication of low-pass
signal by the Hilbert transform of the high-pass signal
6. The Spectral density of the signal
x(t)=1/πt is
a. Equal to spectral density of ‘1/t’
b. Equal to spectral density of ‘t’
c. Equal to spectral density of u(t)
d. None
Answer: [D] None
7. value of impulse function at t=0 is
a) infinity.
b) one.
c) undefined.
d) zero.
Answer: [C] undefined.
8) for real signals
W) Amplitude Spectrum is even.
X) Amplitude Spectrum is odd.
Y) Phase Spectrum is even.
Z) Phase Spectrum is odd.
a) only W.
b) W and Y.
c) X and Y.
d) none.
Answer: [D] none.
9) δ(at) is equal to
a) δ(t/a) / |ܽ|
b) δ(t) / |ܽ|
c) δ(at) / |ܽ|
d) none.
Answer: [B] δ(t) / |ܽ|
10) Which of the following is used for
frequency domain representation of periodic signals
a) Fourier Series
b) Fourier transform
c) both
d) none
Answer: [C] both
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