Amplitude Modulation : DSB-SC : u (t) = m(t) cos 2π t Power P = Conventioanal AM : u (t) = [1 + m(t)] Cos 2π t . as long as |m(t)| ≤ 1 demodulation is simple . Practically m(t) = a m (t) . Modulation index a = ( ) ( ) , m (t) = ( ) | ( )| Power = + SSB-AM : → Square law Detector SNR = ( ) Square law modulator ↓ = 2a / a → amplitude Sensitivity Envelope Detector R C (i/p) < < 1 / R C (o/P) >> 1/ R C << 1/ω