On the Detection of Differentially Encoded Polyphase Signals

Any digital communication system that employs coherent detection requires coherent reference signals for proper operation. This paper is concerned with the transmission and detection of differentially encoded multiple phase-shift-keyed (MPSK) signals and the ambiguity resolution problem that results from suppression of the transmitted carrier. In particular, the paper presents the analysis and performance of differentially encoded coherent MPSK systems that reconstruct coherent reference signals by means of generalized Costas or th power loops. The performance of such systems is then compared with that of ideal reception of MPSK signals and differentially coherent detection of differentially encoded MPSK signals. Emphasis is placed upon the special cases of quadriphase and octaphase signaling.