# signals and systems

Topics: Fourier transform, Fourier series, Laplace transform Pages: 34 (1916 words) Published: September 21, 2013
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Code No: 53021
Set No. 1
II B.Tech. I Sem., I Mid-Term Examinations, August – 2012
SIGNALS AND SYSTEMS
Objective Exam
Name: ______________________________ Hall Ticket No.
A

Answer All Questions. All Questions Carry Equal Marks.Time: 20 Min. Marks: 10.

I

Choose the correct alternative:

1.

The relation between a signum function and a unit step function is ( a ) 2u(t)-1
( b ) 2u(t)
( c ) u(t)-u(-t)
( d ) u(t)-1

2.

In a set of signals, if no signal can be represented as a linear combination of the remaining signals, then such signals are
[
]
( a ) linearly independent
( b ) linearly dependent
( c ) orthonormal
( d ) orthogonal

3.

In the trigonometric Fourier series representation of a signal a0 is the ( a ) RMS value
( b ) peak value
( c ) mean square value

4.

In the frequency spectrum of an aperiodic signal, the spacing among the components is ( a ) large
( b ) small
( c ) infinity
( d ) zero

5.

Fourier transform of a unit impulse function is
( a ) 1/jw
(b)w
(c)1

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[

[
( d ) average value

]

]

[

]

[

]

( d ) 1/w

6.

If the width τ of a pulse of height unity approaches infinity, then its Fourier transform is equal to [
]
(a)1
( b ) πδ(w)
( c ) 2πδ(w)
( d ) infinity

7.

The spectrum of a Gaussian signal is
( a ) Gaussian function ( b ) rectangular function

8.

Parseval’s identity states that

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(a)
9.

1

−∞

4

X ( w) dw

−∞

(b)

2

x (t ) =

1

−∞

[
2

X ( w) dw

( c )  ∫

−∞

X ( w) dw

(d)

−∞

( a )   ∑ −∞ Cn ∂ ( w − nw0 ) ( b )   2π ∑ −∞ Cn ∂ ( w − nw0 ) The Fourier transform of x(-t) is
( a ) X(w)
( b ) X(-w)

]

2

X ( w) dw

The Fourier transform of a periodic function x(t) with period T is ∞

10.

[
]
( c ) triangular function ( d ) sinc function

[

]

( c )   ∑ −∞ Cn ∂ ( w) ( d ) 2π ∑ −∞ Cn ∂ ( nw0 ) ∞

[
( c ) X(1/w)

]

( d ) –X(w)
Cont…..2

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Code No: 53021

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:2:

Set No. 1

II

Fill in the blanks:

11.

Double integration of a unit impulse function results in a unit--------- function.

12.

The representation of a function x(t) by a set of infinite mutually orthogonal functions is called -----representation of x(t)

13.

The Fourier spectrum exists only at --------- frequencies.

14.

The transfer function in s-domain is known, the transfer function in frequency domain can be found by replacing s by--------

15.

The Fourier transform of signals which do not satisfy the condition of absolute convergence contains ----------------------------------------

16.

Hilbert transform shifts the phase of all frequency components of a signal by -------

17.

For distortionless transmission, the bandwidth of the system must be --------

18.

For a continuous time LTI system to be BIBO stable, its--------- must be absolutely integrable.

19.

A system is stable if every bounded input produces a ------- output.

20.

A system whose magnitude function violates the Paley-Wiener criterion has a ----- impulse response.

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Code No: 53021
Set No. 2
II B.Tech. I Sem., I Mid-Term Examinations, August – 2012
SIGNALS AND SYSTEMS
Objective Exam
Name: ______________________________ Hall Ticket No.
A

Answer All Questions. All Questions Carry Equal Marks.Time: 20 Min. Marks: 10.

I

Choose the correct alternative:

1.

In the frequency spectrum of an aperiodic signal, the spacing among the components is ( a )...