A Decision-Directed Differentially Coherent BPSK Detector

Decision feedback is used to improve the quality of the phase references needed for detecting the differentially encoded BPSK messages. Unlike the standard differentially coherent detector, the two quadrature detection references are formed with K symbols just received. To generate the detection phase references, the bi-phase modulation on the received symbols first is removed with decision feedbacks. The modified in-phase and quadrature phase components of K such symbols are linearly combined and then serve as the phase references needed for symbol detections. Transition detection error probabilities are analyzed and used to examine the transient behavoir and the time required for reaching a steady-state.