<Li> P b c (\ displaystyle \ scriptstyle P_ (bc)) = Probability of bit - error per carrier </Li> <Li> P s (\ displaystyle \ scriptstyle P_ (s)) = Probability of symbol - error </Li> <Li> P s c (\ displaystyle \ scriptstyle P_ (sc)) = Probability of symbol - error per carrier </Li> <Li> Q (x) = 1 2 π ∫ x ∞ e − 1 2 t 2 d t, x ≥ 0 (\ displaystyle \ scriptstyle Q (x) \; = \; (\ frac (1) (\ sqrt (2 \ pi))) \ int _ (x) ^ (\ infty) e ^ (- (\ frac (1) (2)) t ^ (2)) dt, \ x \ geq 0) </Li>

5. in analogue transmission of digital data describe what is meant by 256- qam