# 5.4 Phase Shift Keying (PSK)

## Principle of PSK

| With Phase Shift Keying (PSK), the information is contained in the instantaneous phase of the modulated carrier. Usually this phase is imposed and measured with respect to a fixed carrier of known phase – coherent PSK. For binary PSK, phase states of 0o and 180o are used.

#### It is also possible to transmit data encoded as the phase change (phase difference) between consecutive symbols. This method is classified as Differentially Coherent PSK (DSPK).
There is no non-coherent detection equivalent for PSK.

####