Multiple symbol differential detection

DETAILED DESCRIPTION The need in the art is addressed by the present invention which provides a differential detection technique for MPSK signals which uses a multiple symbol observation interval on the basis of which a joint decision is made regarding the phase of the received symbols.
In accordance with the invention, a first difference phase is created between first and second received symbols.
Next the first difference phase is correlated with the possible values thereof to provide a first plurality of intermediate output signals.
A second difference phase is next created between second and third received symbols.
The second difference phase is correlated with plural possible values thereof to provide a second plurality of intermediate output signals.
Next, a third difference phase is created between the first and third symbols.
The third difference phase is correlated with plural possible values thereof to provide a third plurality of intermediate output signals.
Each of the first plurality of intermediate outputs are combined with each of the second plurality of intermediate outputs and each of the third plurality of intermediate outputs to provide a plurality of possible output values for the phase of the second and third symbols.
Finally, a joint decision is made with respect to the output values for the phase of the second and third symbols by choosing from the plurality of possible output values the value which represents the best combined correlation of the first, second and third difference values with the possible values thereof.