Typical signals and their representation Unit Step u(t)(in our textbook u(t)) t>0 t<0 tu(t-to) 0 to u(t)is basic causal signal,multiply which with any non-causal signal to get causal signal.Typical signals and their representation Unit Step u(t) (in our textbook µ(t)) {1 0 0 0 ( ) > = < t t u t u(t) 1 0 t u(t- t0) 1 0 t t 0 u(t) is basic causal signal, multiply which with any non-causal signal to get causal signal