Eight Phase Shift Keying (8PSK) is a method to transmit digital information on a carrier by changing the phase of the carrier. In 8PSK there are 8 different phase changes defined, each phase change represents the transmission of 3 bits. 8PSK is used in e.g. EDGE.
The phase changes are: 0, 45, 90, 135, 180, 225, 270 and 315 degrees.