## QAM generation |
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. |