Signals and Systems - Section 1 (4)

Directions to Solve

Signals and Systems - Section 1

25.

A function having frequency f is to be sampled. The sampling time T should be

A.
B.
C.
D.

Answer: Option C

Explanation:

Sampling frequency must be more than 2f. Therefore 31-213

26.

In Laplace transform, multiplication by e^-at in time domain becomes

A.	translation by a in s domain
B.	translation by (-a) in s domain
C.	multiplication by e-as in s domain
D.	none of the above

Answer: Option A

Explanation:

£e^-at f(t) = F(s + a).

27.

The ROC of sequence in the Z.T. of sequence x[n] = aⁿ ∪ [n] is

A.	z > a
B.	z < a
C.	\|z\| > a
D.	\|z\| < a

Answer: Option C

Explanation:

The simplest method to find the ROC. Put denominator to greater than zero.

28.

The analog signal m(t) is given below m(t) = 4 cos 100 pt + 8 sin 200 pt + cos 300 pt, the Nyquist sampling rate will be

A.	1/100
B.	1/200
C.	1/300
D.	1/600

Answer: Option C

Explanation:

m (t) = 4 cos 100 pt + 8 sin 200 pt + cos 300 pt

Nyquist sampling freq f_s ≤ 2f_m where f_m is highest frequency component in given signal and highest f_m in 3^rd part

2pf_mt = 300 pt

f_m = 150 Hz

f_s = 2 x 150 p 300 Hz

32-287

29.

For the discrete time system of the given figure

09-118

A.	yk - 0.5 yk - 1 - 0.25 yk - 2 = uk
B.	yk + 0.5 yk - 1 - 0.25 yk - 2 = uk
C.	yk - 0.5 yk - 1 + 0.25 yk - 2 = uk
D.	yk + 0.5 yk - 1 + 0.25 yk - 2 = uk

Answer: Option C

Explanation:

u_k + 0.5 y_{k - 1} - 0.25 y_{k - 2} = y_k.

30.

If 19-333 then for this to be true x(t) is

A.	exp (j2p f/t)
B.	exp (-j2p f/t)
C.	exp (j2p ft)
D.	exp (-j2p f/t)

Answer: Option C

Explanation:

If 33-333-1

33-333-3

33-333-4

33-333-5

31.

If I (s) 05-31 , initial value of i(t) is

A.	5A
B.	12.5 A
C.	0.05 A
D.	1250 A

Answer: Option A

Explanation:

29-30

32.

The continuous time system with impulse response h(t) = 24-409 is stable, for n is even, when

A.	a = 0
B.	a > 0
C.	a < 0
D.	a ≤ 0

Answer: Option C

Explanation:

35-409-1

35-409-2

35-409-3

35-409-4

For stable system exponential must be -ve so that a < 0.

Signals and Systems - Section 1 (4)

Signals and Systems - Section 1

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