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The impulse response of a system consists of two delta function as shown in the given figure.
The input to the system is a unit amplitude square pulse of one unit time duration. Which one of the following depicts the correct output?
Correct Option: B
Given that impulse response i.e.
h(t) = 1.δ(t) – | δ(t – 1) | |
2 |
or H(s) = 1 – | e–s | |
2 |

Also, given x(t) = unit amplitude pulse of one unit time duration i.e.
or x(t) = u(t) – u(t – 1)
or X(s) = | - | e–s | ||
s | s |

Now, Y(s) = H(s).X(s)
or Y(s) = | ![]() | 1 - | e–s | ![]() | ![]() | - | e–s | ![]() | |||
s | s | s |
or Y(s) = | - | . | e–s | + | e–s | |||||
s | 2 | s | 2 | s |
or Y(s) = | - | - e–s | - | e–s | + | e–2s | ||||||
s | s | 2 | s | 2 | s |
Taking inverse Laplace transform

or y(t) = u(t) – u(t – 1) – 1/2 · u(t – 1) + 1/2 u(t – 2)
or y(t) = u(t) – 3/2 u(t – 1) + 1/2 u(t – 2)
Hence, alternative (B) is the correct choice.