Part D: Time Invariance

A time-invariant system is one whose output is not dependant only on time. That is to say that if

x(t) --> |System| --> y(t)

then

x(t-to) --> |System| --> y(t-to).

Example 1: Time invariant y(t) = 42*x(t)

x(t) --> |Time Delay| --> y(t-to)= x(t-to) --> |System| --> z(t) = y(t-to) = 42*x(t-to)

and

x(t) --> |System| --> y(t)= 42*x(t) --> |Time Delay| --> z(t-to) = y(t-to) = 42*x(t-to)


Example 2: Time variant y(t) = t^2*x(t)


x(t) --> |Time Delay| --> y(t-to)= x(t-to) --> |System| --> z(t) = y(t-to) = t^2*x(t-to)

but

x(t) --> |System| --> y(t)= t^2*x(t) --> |Time Delay| --> z(t-to) = y(t-to) = (t-to)^2*x(t-to)

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