What is the phase shift of QPSK when a symbol changes?

[bhanesh]

What is phase shift of qpsk when symbol change occurs ?

Can anybody explain please ?

 

[the_emi_guy]

QPSK is a form of "coherent" modulation. In coherent modulation the receiver contains a reference clock that is frequency locked to the received signal. Data is encoded by changing the received signal's phase and amplitude relative to the reference clock. Phase shifts are illustrated in the attached picture.

 

[sophiecentaur]

What is phase shift of qpsk when symbol change occurs ?

Can anybody explain please ?

Did you look at Wikipedia? Have you any questions about their treatment of QPSK?