QAM(Quadrature Amplitude Modulation):
• QAM is a combination of ASK and PSK
Two different signals sent simultaneously on the same carrier frequency ie, M=4, 16, 32, 64, 128, 256.
As an example of QAM, 12 different phases are combined with two different amplitudes. Since only 4 phase angles have 2 different amplitudes, there are a total of 16 combinations. With 16 signal combinations, each baud equals 4 bits of information (2 ^ 4 = 16). Combine ASK and PSK such that each signal corresponds to multiple bits. More phases than amplitudes. Minimum bandwidth requirement of QAM is same as ASK or PSK.