Pseudo coherent demodulation method

摘要

The method demodulates a noisy signal in which at least the phase is differentially modulated. The received symbols (R(i,k)) are present as complex symbols and are demodulated with respect to the previous received symbol of the same channel. The amplitude and/or phase of the received symbols can be delayed by a transmission factor of the radio channel. The demodulated complex symbol in a rotation symmetrical locus diagram of possible discrete values is allocated to transmission symbols (S(i,k)). The diagram is sub-divided into compartments (FG). The channel transmission factor (H(i,k)) is approximately calculated from the comparison of a first received symbol with the associated transmission symbol according to amplitude and phase. The approximately calculated phase offset is ambiguous by amounts which correspond to a whole number multiple of the phase difference angle between two phase positions of the diagram. The calculated transfer factor is used with the demodulation of the next received symbol to correct the noise component.