1. A communication system for the dissemination of digital data constituted by a succession of 0 and 1 bits coming from a data source, said communication system comprising: grouping means fed from said data source for grouping said bits in the form of vectors of N binary components, orthogonal Walsh Hadamard transformation means receiving the vectors having said binary components and converting them into orthogonal vectors each having N analogue components, analogue means arranged for disseminating said orthogonal vectors, a compensating circuit adapted for detecting the amplitude fluctuations experienced by said orthogonal vectors in said analogue means, said compensating circuit comprising a storage circuit, having an output, for temporarily storing characteristic values of said amplitude fluctuations, reverse transformation means receiving the disseminated orthogonal vectors, available at the output of said analogue means and means for reconstituting said succession of bits from the reconstructed vectors of N binary components furnished by said reverse transformation means, said means for reconstituting said succession of bits comprising a reshaping means operating at an adjustable decision level, said reshaping means having an adjusting input coupled to the output of said storage circuit, said decision level being adjusted according to said characteristic values.