The invention concerns a method for demodulating a digital signal received via a transmission channel, comprising a step which consists in associating with each value received of said received signal a point of the corresponding modulation constellation, on the basis of the decision boundaries taking into account the potential effect of a phase shift on at least one of said points of the modulation constellation and of the potential effect of an Gaussian additive noise applied on said point, said Gaussian additive noise being represented by a generating surface associated with said point, and said phase shift by a rotation on an angular range based so that said swept surface belongs essentially to the region of decision associated with the corresponding point of the modulation constellation, plotted on the basis of at least one phase and/or amplitude characteristic of said modulation, so as to associate with each of said points of the constellation a portion of a reception space, called corresponding region of decision.