# Electronics and Communication Engineering - Signals and Systems

### Exercise :: Signals and Systems - Section 3

1.

Transfer function of a linear system is 200 e-j10ω The system is a

 A. distortionless Attenuator B. amplifier with Phase distortion C. distortionless Amplifier D. attenuator with Phase distortion

Explanation:

Because H(ω) = 200 e-j10ω

And |H(ω)| = 200 with zero phase.

So it cannot be attenuator.

2.

which one is discrete time periodic signal?

 A. sin 3pn B. cos 2pn C. sin 3pn D. all

Explanation:

In Discrete time signal irrational function cannot be periodic, frequency must be rational.

Hence only (c) is periodic.

sin 3pn = sin 3p(n + N) ⇒ for Periodic 3pN = 2Kp   .

3.

Frequency domain of a periodic triangular function is a

 A. discrete sinc function B. continuous sampling function C. discrete sampling function D. continuous sampling square function

Explanation:

Because F.T. of a Triangular function is square sampling function.

4.

The z-transform of sequence n x x[n] is

 A. B. C. D. Explanation:

It is differentiation property.

5.

The inverse Laplace transform of A. eat B. -eat C. 1 - eat D. -1 + eat .