Carrier-phase adjustment using absolute phase detector

Abstract

Disclosed is a modulation-demodulation system and method for transmitting a plurality of sequentially received information bit sequences, the system including a transmitter having a state machine for expanding by a coding process each information bit sequence into an expanded bit sequence with a coded bit group portion and, in some cases, an uncoded bit group portion. The transmitter further includes a modulator for modulating a carrier signal by one of a plurality of multilevel symbols in a two-dimensional complex plane in response to each sequentially applied expanded bit sequence, with the coded bit group portion being used to specify a subset of the multilevel symbols which when rotated in the complex plane maps upon another subset for each adverse angular rotation and the uncoded bit group portion being used to specify for a selected multiple symbol subset the transmitted multilevel symbol of the carrier signal. The system further includes a receiver having a demodulator and slicer for demodulating and detecting the modulated carrier signal to obtain the expanded bit sequences; a phase rotation detector, coupled to the slicer, for uniquely identifying each adverse angular rotation by analyzing a plurality of sequentially applied coded bit group portions; and a phase corrector, coupled to the phase rotation detector, for compensating for the adverse angular rotation.