Show that the power spectral density of a CAP signal with a

Show that the power spectral density of a CAP signal with a total of L amplitude levels is defined by S(f) = s2A/T |P(f)|2 where |P(f)| is the magnitude spectrum of the pass band in phase pulse p(t); the s2A is the variance of the complex symbols Ai = ai + jbi, which is defined by