Differential Quadrature Phase Shift Keying is a modulation technique in which the carrier can expect one of four phases, each difference of phase, addressing 2 bits. Subsequently the data information can convey 2 bits at same time. The Combinations of bits is 00, 01, 11 and 10. Utilizing this procedure the phase transition across the beginning is kept away from. QPSK communicates twice the information rate in a given bandwidth contrasted to BPSK at the similar BER. The design penalty that is paid is that QPSK transmitters and receivers are more muddled than the ones for BPSK.