# differential binary phase shift keying (DSSS) (DBPSK)

Differential phase shift keying( DPSK) is a type of phase shift keying in which information is transmitted by changing the phase of the carrier frequency.

With DPSK keying, as with quadrature phase shift keying( QPSK), ambiguities can occur if the phase changes during transmission. For this reason, in Differential Binary PhaseShift Keying (DBPSK), the phase position is changed with the signal and is not fixed.

For example, DBPSK transmits a digital "1" by rotating the phase position by 180°, and a binary "0" by adding one of 0° to the current phase position. So if two "ones" are transmitted in succession, the first can have the phase position 0°, the second is in any case rotated by 180°.