What is 8QAM (8 Quadrature Amplitude Modulation)?

QAM is Quadrature Amplitude Modulation is a method of combining two amplitude-modulated signals into a single channel. It also can double the effective bandwidth. It is used with pulse amplitude modulation (PAM) in digital systems, especially in wireless communications. High spectral efficiencies can be achieved by this technique. 8 QAM is able to modulate 3 bits per symbol.