Free Printable EC8352-SIGNALS AND SYSTEMS-MODEL 2

1.

Damped sinusoids are _____

a)

sinusoid signals multiplied by growing exponentials

b)

sinusoid signals divided by growing exponentials

c)

sinusoid signals multiplied by decaying exponentials

d)

sinusoid signals divided by decaying exponentials

2.

Which mathematical notation specifies the condition of periodicity for a continuous time signal?

a)

x(t) = x(t +T0)

b)

x(n) = x(n+ N)

c)

x(t) = e-αt

d)

None of the above

3.

A system is said to be shift invariant only if______

a)

a shift in the input signal also results in the corresponding shift in the output

b)

a shift in the input signal does not exhibit the corresponding shift in the output

c)

a shifting level does not vary in an input as well as output

d)

a shifting at input does not affect the output

4.

Which among the following are the stable discrete time systems?

1. y (n) = x (4n)

2. y (n) = x (-n)

3. y (n) = ax (n) + 8

4. y (n) = cos x (n)

a)

1 & 3

b)

2 & 4

c)

1, 3 & 4

d)

1, 2, 3 & 4

5.

A system which is linear is said to obey the rules of

a)

homogeneity

b)

scaling

c)

additivity

d)

both scaling and additivity

6.

A signal g(t) = A then g(t) is a

a)

energy signal

b)

power signal

c)

neither energy nor power signal

d)

insufficient data

7.

The Fourier series of an odd periodic function contains

a)

odd harmonics only

b)

even harmonics only

c)

cosine harmonics only

d)

sine harmonics only

8.

What is the nature of Fourier representation of a discrete & aperiodic signal?

a)

Continuous & periodic

b)

Discrete & aperiodic

c)

Continuous & aperiodic

d)

Discrete & periodic

9.

Which property of periodic signal in DTFS gets completely clarified / identified by the equation x (n – n0)?

a)

Conjugation

b)

Time Shifting

c)

Frequency Shifting

d)

Time Reversal

10.

How does Fourier series make it easier to represent periodic signals?

a)

Harmonically related

b)

Periodically related

c)

Sinusoidally related

d)

Exponentially related

11.

If x(t) and y(t) are two periodic signals with coefficients Xn and Yn then the linearity is represented as?

a)

ax(t) + by(t) = aXn + bYn

b)

ax (t) + by(t) = Xn + bYn

c)

ax(t) + by(t) = aXn + Yn

d)

ax(t) + by(t) = Xn + Yn

12.

Generally, the convolution process associated with the Laplace Transform in time domain results into________

a)

Simple multiplication in complex frequency domain

b)

Simple division in complex frequency domain

c)

Simple multiplication in complex time domain

d)

Simple division in complex time domain

13.

According to the time-shifting property of Laplace Transform, shifting the signal in time domain corresponds to the ______

a)

Multiplication by e-st0 in the time domain

b)

Multiplication by e-st0 in the frequency domain

c)

Multiplication by est0 in the time domain

d)

Multiplication by est0 in the frequency domain

14.

What should be the value of laplace transform for the time-domain signal equation e-at cos ωt.u(t)?

a)

1 / s + a with ROC σ > – a

b)

ω / (s + a) 2 + ω2 with ROC σ > – a

c)

s + a / (s + a)2 + ω2 with ROC σ > – a

d)

Aω / s2 + ω2 with ROC σ > 0

15.

If the Laplace transform of a signal y(t) is $Y\left(s\right)=\frac{1}{s\left(s-1\right)}$ then its final value is

a)

-1

b)

0

c)

1

d)

Unbounded

16.

When do DTFT and ZT are equal?

a)

When σ = 0

b)

When r = 1

c)

When σ = 1

d)

When r = 0

17.

Find the Z-transform of δ(n+3).

a)

z

b)

$z^{2\ }$

c)

1

d)

$z^3$

18.

The z-transform of a signal X(n) whose definition is given by X(z)=

\sum_{n=0}^{\infty}x\left(n\right)z^{-n}

is known as

a)

Unilateral Z-transform

b)

Bilateral Z-transform

c)

Rational Z-transform

d)

None of the above

19.

For what kind of signals one sided Z-transfrom is unique

a)

All signals

b)

Anti-causal signal

c)

Causal signal

d)

None of the above

20.

$The\ value\ of\ the\ Radius\ of\ convergence\ of\ f\left(n\right)=2^n,n<0\ is$

a)

0< $\left|z\right|$ <1

b)

-2< $\left|z\right|$

c)

$\left|z\right|$ <2

d)

z-plane

21.

$The\ ROC\ of\ u\left(n\right)=4^n,for\ n<0;2^n,for\ n\ge0\ is$

a)

0<z<1

b)

z<4

c)

2<z

d)

2<z<4

22.

$The\ value\ of\ inverse\ z-transform\ of\ \log\left(\frac{z}{z+1}\right)is$

a)

$\frac{\left(-1\right)^n}{n}for\ n=0;\ \ 0\ otherwise$

b)

$\frac{\left(-1\right)^n}{n}$

c)

$0,\ for\ n=0;\ \ \frac{\left(-1\right)^n}{n},otherwise$

d)

$0$

23.

According to Time shifting property of z-transform, if X(z) is the z-transform of x(n) then what is the z-transform of x(n-k)?

a)

z^kX(z)

b)

z^-kX(z)

c)

X(z-k)

d)

X(z+k)

24.

The Dirichlet condition for (DTFT) is……

a)

DT Signal should be absolutely differentiable

b)

DT Signal should be absolutely multipliable

c)

DT Signal should be absolutely integrable

d)

DT Signal should be absolutely summable

25.

The DTFT is used to

a)

convert frequency spectrum domain to discrete time domain

b)

convert discrete time domain to continuous frequency

spectrum domain

c)

convert analog signal to digital signal

d)

convert digital signal to analog signal

26.

$\int_{-\infty}^{\infty}\ \left(t-2\right)^2\delta\left(t-2\right)dt$

a)

$4$

b)

$2$

c)

$\left(t-2\right)$

d)

$0$

27.

$The\ signal\ x\left(t\right)=A\ \sin\left(\omega_{o\ }t+\phi\right)\ is$

a)

a power signal

b)

an energy signal

c)

periodic signal

d)

both periodic and power signal

28.

$x\left(t\right)=r\left(t\right)\ -r\left(t-2\right)\ is\ a\$

a)

power signal

b)

energy signal

c)

nor power nor energy

d)

both energy and power

29.

What is the period of the following signal, x(t) = sin(18*pi*t + 78 deg)?

a)

¹⁄₉

b)

²⁄₉

c)

¹⁄₃

d)

⁴⁄₉

30.

For the signal, x(t) = log(cos(a*pi*t+d)) for a = 50 Hz, what is the time period of the signal, if periodic?

a)

0.16s

b)

0.08s

c)

0.12s

d)

0.04s

31.

Fundamental frequency of

x\left[n\right]

is given by ___________

a)

$\omega=\frac{\pi}{N}m$

b)

$\omega=\frac{2\pi}{N}m$

c)

$\omega=\frac{2\pi N}{m}$

d)

$\omega=\frac{4\pi}{N}m$

32.

If the Fourier series coefficients of x(t) are $c_n$ , the the Fourier series coefficients of $x\left(-t\right)$ is given by

a)

$c_n$

b)

$c_{-n}$

c)

$-c_n$

d)

$-c_{-n}$

33.

For the signal shown in above figure, which of the following is $x\left(3t\right)$

a)

b)

c)

d)

34.

Find the Fourier series representation of the signal is

x\left(t\right)=\frac{\cos2\pi t}{3}

and determine the Fourier series coefficients.

a)

$c_0=1,\ c_1=\frac{1}{6},\ c_{-1}=\frac{1}{6}$

b)

$c_1=\frac{1}{6}$

c)

$c_{-1}=\frac{1}{6}$

d)

$c_1=\frac{1}{6},\ c_{-1}=\frac{1}{6}$

35.

Determine the odd component of the signal: x(t)=cost+sint.

a)

sint

b)

2sint

c)

cost

d)

2cost

36.

Find the fourier transform of an exponential signal f(t) = e-at u(t), a>0

a)

1/

a+jω

b)

1/

a-jω

c)

1/

-a-jω

d)

1/

-a+jω

37.

Find the fourier transform of the unit step function

a)

πδ(ω) + 1/ω

b)

πδ(ω) + 1/jω

c)

πδ(ω) – 1/jω

d)

δ(ω) + 1/jω

38.

Laplase of 1 is

a)

1/s-a

b)

1/s

c)

1/s+a

d)

0

39.

Find the Fourier Transform of an Exponential signal

f\left(t\right)=e^{-at}u\left(t\right),a>0

a)

$\frac{1}{a+jw}$

b)

$\frac{1}{a-jw}$

c)

$\frac{1}{-a+jw}$

d)

$\frac{1}{-a-jw}$

40.

If x(n) is a DT signal then the equation x (n – n₀ ) indicates the basic ………..property.

a)

Linearity

b)

Time Reversal

c)

Frequency Shifting

d)

Time Shifting

41.

Determine the Nyquist rate and Nyquist interval for Cos(4πt).

a)

4 Hz, 0.25 sec

b)

0.5 Hz, 0.5 sec

c)

0.5 Hz, 2 sec

d)

2 Hz, 0.5 sec

42.

The Nyquist theorem for sampling (choose from arguments given below)

1) Converts time domain to frequency domain

2) Helps in quantization

3) Limits the bandwidth requirement

4) Provide the spectrum of the signal

a)

only 3 is correct

b)

1 and 2 are correct

c)

1 and 3 are correct

d)

All the four are correct

43.

What is the DTFT of the four point sequence x(n)={1,0,1,0}?

a)

{-2, 0,-2,0}

b)

{2,-2-2j,2,-2+2j}

c)

{2,-2+2j,-2,-2-2j}

d)

{2,0,2,0}

44.

The transforming relations performed by DTFT are

1)Linearity

2) Modulation

3) Shifting

4) Convolution

a)

1, 2 and 3 are correct

b)

1, and 2 are correct

c)

1 and 3 are correct

d)

All the four are correct

45.

The z – transform of a system is 𝐻(𝑧) = 𝑧 /𝑧 − 0.2 If the ROC is |𝑧| < 0.2, then the impulse response of the system is

a)

(a) (0.2)^ 𝑛 𝑢[𝑛]

b)

(b) (0.2)^2 𝑢[−𝑛 − 1]

c)

(c) −(0.2) ^2 𝑢[𝑛]

d)

(d)−(0.2)^ 𝑛 𝑢[−𝑛 − 1]

EC8352-SIGNALS AND SYSTEMS-MODEL 2

Total questions: 45

Worksheet time: 3600secs

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