# 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

JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD

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

D

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O

W

U

[

[

( 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

T

N

J

(a)

9.

1

2π

∫

∞

−∞

4

X ( w) dw

∫

∞

−∞

(b)

2

x (t ) =

1

2π

∫

∞

−∞

[

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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-o0o-

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Code No: 53021

Set No. 2

JAWAHARLAL NEHRU TECHNOLOGICAL UNIVERSITY HYDERABAD

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 )...

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