Differential Detection with Intersymbol Interference and Frequency Uncertainty

In this paper we study differential detection of binary differential phase shift keyed (DPSK) signals with several impairments typical in satellite communication systems. In particular, the bit error rate is determined for bit timing error and frequency offset error at the receiver. The effect of a hard-limiting, band-limited repeater is also considered. The differential detector performance is determined for both conventional DPSK signals (with 0 and π phase shifts) and symmetrical DPSK signals (with - \pi/2 and + \pi/2 phase shifts). With symmetrical DPSK, adjacent bit signals are orthogonal rather than either in or out of phase. Therefore, with intersymbol interference, the error rates for all bits are equal and the average bit error rate is less with symmetrical DPSK, as shown in this paper.