# Discrete Time Signals MCQ’s

This set of Signals & Systems Multiple Choice Questions & Answers (MCQs) focuses on “Discrete Time Signals”.

1. What is the time period of the function x[n] = exp(jwn)?
a) pi/2w
b) pi/w
c) 2pi/w
d) 4pi/w

2. What is the nature of the following function: y[n] = y[n-1] + x[n]?
a) Integrator
b) Differentiator
c) Subtractor
d) Accumulator

3. Is the function y[n] = sin(x[n]) periodic or not?
a) True
b) False

4. Is the above function defined, causal in nature?
a) True
b) False

5. Is the function y[n] = x[n-1] – x[n-56] causal?
a) The system is non causal
b) The system is causal
c) Both causal and non causal
d) None of the mentioned

6. If n tends to infinity, is the accumulator function a stable one?
a) The function is marginally stable
b) The function is stable
c) The function is unstable
d) None of the mentioned

7. Is the function y[n] = x[n-1] – x[n-4] memoryless?
a) True
b) False

8. Is the function y[n] = y[n-1] + x[n] stable in nature?
a) It is stable
b) It is unstable
c) Both stable and unstable
d) None of the mentioned

9. We define y[n] = nx[n] – (n-1)x[n]. Now, z[n] = z[n-1] + y[n], is z[n] stable?
a) Yes
b) No

10. Discrete-time signals are _________________
a) Continuous in amplitude and continuous in time
b) Continuous in amplitude and discrete in time
c) Discrete in amplitude and discrete in time
d) Discrete in amplitude and continuous in time

11. Determine the value of the summation: ∑n= -∞δ(n-1)sin2n.
a) 1
b) 0
c) sin2
d) sin4

12. We define y[n] = nx[n] – (n-1)x[n]. Now, z[n] = z[n-1] + y[n]. Is z[n] a causal system?
a) No
b) Yes

13. Determine the discrete-time signal: x(n)=1 for n≥0 and x(n)=0 for n<0
a) Unit ramp sequence
b) Unit impulse sequence
c) Exponential sequence
d) Unit step sequence

14. Determine the value of the summation: ∑n= -∞ δ(n+3)(n2+n).
a) 3
b) 6
c) 9
d) 12

15. Determine the product of two signals: x1 (n) = {2,1,1.5,3}; x2 (n) = { 1,1.5,0,2}.
a) {2,1.5,0,6}
b) {2,1.5,6,0}
c) {2,0,1.5,6}
d) {2,1.5,0,3} 5 Star
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