####

## Performance of M-ary PSK

#### Increasing the number of symbol states for M-ary PSK beyond four allows further improvements in bandwidth efficiency, but the additional symbol states are no longer orthogonal (they do not lie on the sine or cosine axis of the constellation diagram). The result is that the performance in noise for M > 4 degrades rapidly as M increases. |

#### The bandwidth efficiency for M-ary PSK is: #### Maximum bandwidth efficiency (M-ary PSK) = log2 M bits/second/Hz