# Operations on Signals

This set of MATLAB Multiple Choice Questions & Answers (MCQs) focuses on “Operations on Signals”.

1. What is the following graph if u(t) denotes step function?

a) u(t+0)
b) u(t)-u(t-1000)
c) u(t-0)
d) u(t)

2. What is the following graph if u(t) denotes step function and r(t) denotes ramp function?

a) r(t)
b) r(t)-r(t-50)-u(t-50)
c) r(t)-r(t-50)
d) r(t)-u(t-50)

3. What does the following code generate?

```p=ones(1,90);
t=(0:1:89);
plot(t,p);```

a) A graph of a unit step function
b) A graph of a pulse function
c) A graph of a triangular pulse function
d) An impulse function

4. What is the following graph, if del(t) represents the impulse function?

a) del(t)
b) del(t-100)
c) del(t+100)
d) del(t-50)

5. The convolution of [1 2 1] and [1 2 1] will have the highest amplitude at t= _________
a) 3 units
b) 0 units
c) 1 unit
d) 2 units

6. What is the output of the following code?

```a=[1 2 3];
b=2;
a.\b;```

a) .5 1 1.5
b) 2 1 .67
c) Error
d) Cannot be determined

7. What is the output of the following code?

```a=[1 2 3];
b=2;
conv(a,b)```

a) 2 4 6
b) 1 2 3
c) 0 0 0
d) 2 3 1

8. What is the output of the following code?

```T=0:1:9;
stem(T);```

a) A ramp function
b) r[n]-r[n-9]-9u[n-9]
c) r[n]-r[n-9]
d) Error

9. What is the output of the following code?

```Y=rectpulse(1,9);
t=0:1:8;
plot(t,y);```

a) A rectangular pulse extending from 0 to 8 units in time
b) A rectangular pulse with increasing amplitude
c) Error
d) Cannot be determined

10. What is the output of the following code?

```Y=rectpulse(1,9);
p=y’;
t=0:1:9;
plot(t,p);```

a) u(t)-u(t-9)
b) u(t) till 9 units in time
c) Error
d) Cannot be determined

11. What is the output of the following code?

`plot([-5:1:5],tripuls([-4:1:4])`

a) Error
b) Generates a triangular pulse signal
c) Generates a sawtooth signal
d) Cannot be determined

12. What is the output of the following code?

```b={1 2 3};
c={ 1 2 3}
b+c```

a) Error
b) { 2 4 6 }
c) { 1 2 3 }
d) Cannot be determined

13. What is the output of the following code?

```t=[0:1:2];
plot(t,p);
hold;
plot(-t,p);```

a) A mirror image of ramp function from 0 to 2 units in time
b) A ramp function from 0 to 2 units in time and it’s a mirror image in the same window
c) A ramp function from 0 to 2 units in time
d) Error

14. Discrete time convolution is not possible in MATLAB.
a) True
b) False

15. plot([0:1:8],[rectpulse(1,9)]’) and plot([0:1:8],ones(1,9)) will generate the same graph.
a) True
b) False

16. If x(t-5)=0 for t<5 = A for t>=5, the signal is ___________
a) Causal
b) Symmetric
c) Linear, Time Invariant and Causal
d) Cannot be determined

17. What is the output of the following code?

```>>p=[zeros(1,5),ones(1,6)];
>> t=0:1:10;
>> plot(t,p);```

a) r(t-5)-r(t-6)-u(t-10)
b) r(t-5)-u(t-6)-u(t-10)
c) r(t-5)-u(t-6)-r(t-10)
d) r(t-5)-r(t-6)-r(t-10)

18. What is the output of the following code?

`[l,m]=deconv([4 6 8],[2 3 4])`

a) l=2,m=0
b) m=2,l=0
c) l=m=2
d) Error

19. What is the output of the following code?

`stem([0:1:19],[zeros(1,5) [rectpulse(1,5)] zeros(1,5) 2*[rectpulse(1,5)]])`

a) Error in the input of the y axis
b) A function whose step size increases to 1 at t=5 and to 2 at t=15
c) A function whose step size increases to 1 at t=4 and to 2 at t=14
d) Syntactical Error

20. What is the output of the following code?

```a=[zeros(1,4) [rectpulse(1,5)]’ zeros(1,6) 2*[rectpulse(1,9)]’];
stem([0:1:22],a];```

a) Error in the input of the y axis
b) A function whose step size increases to 1 at t=5 and to 2 at t=15
c) A function whose step size increases to 1 at t=4 and to 2 at t=14
d) Error in the input of the x axis