1
GATE EE 2017 Set 1
+2
-0.6
Let the signal $$x\left(t\right)=\sum_{k=-\infty}^{+\infty}\left(-1\right)^k\delta\left(t-\frac k{2000}\right)$$$be passed through an LTI system with frequency response $$H\left(\omega\right)$$, as given in the figure below The Fourier series representation of the output is given as A 4000+4000cos(2000$$\mathrm\pi$$t)+4000cos(4000$$\mathrm\pi$$t) B 2000+2000cos(2000$$\mathrm\pi$$t)+2000cos(4000$$\mathrm\pi$$t) C 4000cos(2000$$\mathrm\pi$$t) D 2000cos(2000$$\mathrm\pi$$t) 2 GATE EE 2015 Set 1 MCQ (Single Correct Answer) +2 -0.6 The signum function is given by $$\mathrm{sgn}\left(\mathrm x\right)=\left\{\begin{array}{l}\frac{\mathrm x}{\left|\mathrm x\right|};\;\mathrm x\neq0\\0\;;\;\;\mathrm x=0\end{array}\right.$$$ The Fourier series expansion of sgn(cos(t)) has
A
only sine terms with all harmonics.
B
only cosine terms with all harmonics
C
only sine terms with even numbered harmonics.
D
only cosine terms with odd numbered harmonics.
3
GATE EE 2009
+2
-0.6
The Fourier Series coefficients, of a periodic signal $$x\left( t \right),$$ expressed as $$x\left( t \right) = \sum {_{k = - \infty }^\infty {a_k}{e^{j2\pi kt/T}}}$$ are given by
$${a_{ - 2}} = 2 - j1;\,\,{a_{ - 1}} = 0.5 + j0.2;\,\,{a_0} = j2;$$
$${a_1} = 0.5 - j0.2;\,\,{a_2} = 2 + j1;\,\,$$ and
$${a_k} = 0;$$ for $$|k|\,\, > 2.$$

Which of the following is true?

A
$$x(t)$$ has finite energy because only finitely many coefficients are non $$-$$ zero
B
$$x(t)$$ has zero average value because it is periodic
C
the imaginary part of $$x(t)$$ is constant
D
The real part of $$x(t)$$ is even
4
GATE EE 2008
+2
-0.6
Let x(t) be a periodic signal with time period T. Let y(t) = x(t - t0) + x(t + t0) for some t0. The Fourier Series coefficient of y(t) are denoted by bk. If bk=0 for all odd k, then t0 can be equal to
A
T/8
B
T/4
C
T/2
D
2T
EXAM MAP
Medical
NEET