Quadrature phase demodulation using a training sequence and a local signal offset from the received carrier frequency.

摘要

A phase modulated signal is quadrature demodulated (37) using a locally generated (36) signal which has a frequency different from that of the received carrier. The demodulation of a known symbol sequence and of a data symbol sequence respectively result in first and second signal vectors. The first signal vector has in-phase and quadrature components, which are converted to phase values (substantially at the symbol rate). An error signal is formed by comparing (44) the phase difference between adjacent symbols (42,43) with a reference (45). The error signal is averaged (46), and the average value (47) is used to correct (39) the second signal vector. The correction signal may be generated using the received carrier signal.