Carrier recovery system for digital signal transmissions

摘要

The system includes a converter for a received, coded signal in a baseband with two quadrature components. The signal is digitised and a decision device estimates the state of a constellation which is closest to the digitised baseband signal. A synchronisation device estimates the phase difference between the estimated state and the baseband signal for phase correction (34) by generating a correction signal. The two components define a point representing a received signal in the in-phase or quadrature planes. First zones contain individually a constellation state and a correction signal which is proportional to the phase difference measured. The synchronisation device is in second zones, exterior to the first zones. The correction signal varies according to the phase difference with a weighted coefficient dependent on a decision signal. The weighted coefficient decreases progressively when the decision point passes the border of the first zone nearest to the point as far as a limit positioned at an equal distance for adjacent states.