Electronics and Communication Engineering  Signals and Systems
Exercise :: Signals and Systems  Section 7
1. 

Answer: Option A
Explanation:

2. 
If 
A. 
j sgn (f) x X(f)  B. 
j2pf x e^{jptf} X(f)  C. 
 D. 

Answer: Option A
Explanation:

3. 
Which of the following is/are not a property/properties power spectral density function Sx(ω)? 
A. 
Sx(ω) is real function of ω  B. 
Sx(ω) is a even function of ω  C. 
Sx(ω) is nonpositive function of ωSx(ω) ≤ 0 for all ω  D. 
All of the above 
Answer: Option C
Explanation:

4. 
A casual LTI system is described by the difference equation 2y[n] = ay[n  2]  2x[n] + βx[n 1] The system is stable only if 
A. 
a = 2 β < 2  B. 
a > 2 β > 2  C. 
a < 2 any value of β  D. 
β < 2, any value of a 
Answer: Option C
Explanation:

5. 
Which of the following can be impulse response of a casual system? 
Answer: Option B
Explanation:
