Property 7: Causal LTI System
Definition in my own words: if a LTI system is causal(no matter it's CT or DT), then the system will always gives a zero output if the time n or t is less than zero.
Example that satisfies this property:
h(t)=u(t-2)*e^(-4t)
if t<0, h(t)=0*e^(-4t)=0; so this system is causal.
Example that doesn't satisfy this property:
h(t)=u(3-t)*e^(-6t)
if t<0, h(t)=1*e^(-6t)=e^(-6t) and it's not equal to zero; so this system is not causal.
