QAM generation

Examples
Example 6.1

The simplest form of QAM is in fact the QPSK symbol set, which can be viewed as two quadrature amplitude modulated carriers, with amplitude levels of +A and -A. Increasing the number of amplitude levels on each carrier to 4, for example, +/-A, +/-3A, gives 16 possible combinations of symbols at the transmitter output, each equally spaced on the constellation diagram, and each represented by a unique amplitude and phase.

Pulse shaping is performed by filtering the multi-level baseband input symbol streams in exactly the same manner as would be used for a binary ASK waveform.

The modulator is again making use of orthogonality of the sine and cosine carriers to allow independent detection of the two M-ary ASK data streams at the receiver.