Question

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)

This question was posed to me in homework.

Query is from Operations on Signals in portion Digital Signal Processing of MATLAB

Answer 1

Correct answer is (b) u(t)-u(t-1000)

To explain I would say: The unit step signal extends from 0 to infinity. When we plot it in MATLAB, we bound it to a certain point in time. In this case, we have bounded it to 1000 units in time. Hence, option u(t)-u(t-1000) is correct. Option a, c and d mean the same thing but it’s not possible to represent the unit step function graphically.