A system is Time Invariant if:
Examples
Time-Invariant System
y = 2x(t) x1(t) -> x1(t-t0) -System-> 2x1(t-t0) x2(t) -System-> 2x2(t) -> 2x2(t-t0) Therefore, this system is Time Invariant
Time-Variant System
y = x(2t) x1(t) -> x1(t-t0) -System-> x1(2t-t0) x2(t) -System-> x2(2t) -> x2(2(t-t0)) Therefore, this system is Time Variant because the outputs do not match.