Qpsk & Qam

[agers]

Pls help me understand and explain in lay mans term the QPSK and QAM.

 

[berck]

QPSK means quadrature phase shift key where you have four states. You can also have BPSK (bi phase, two states), 8PSK (8 states), etc. All the phase locations are found on a unit circle.

QAM means quadrature amplitude modulation and the term is generic because the number of states aren't defined. You can have 16QAM, 32QAM, 64QAM, etc. These states are generally made up in a box shape or square. The more states, the more dots are contained in the box.

In general, QAM can handle higher data rates than QPSK. Particularly if the number of states is higher. The disadvantage is that these higher rates also use up more bandwidth, more power and they are more susceptible to noise.

More in-depth information can be found on Wikipedia for PSK and QAM