Multi-carrier transmission process and system in a difficult environment with optimisation of emission power

A data transmission process, from a first unit (1) to a second unit (2), the two units (1, 2) being in communication via a channel (11), the process comprising at least the following stages:

• digital analog conversion by means of a digital analog converter (8) of data to obtain an analog signal forming support of the data, amplification of said analog signal, prior to its emission via the channel (11) by means of an amplifier (9), characterised in that the process further comprises at least the following stages:
• completing at least two distinct scramblings (20, 21) of the data, such that there are at least two sets of scrambled data, determination of the inverse Fourier Transform of said at least two sets of scrambled data, determination of the dynamics in amplitude of each of said at least two sets of scrambled data after inverse Fourier Transform, selection (26) of one of the sets of scrambled data intended for emission among said inverse Fourier Transforms of the sets of scrambled data having a dynamic in amplitude compatible with the maximum permitted dynamics by the assembly formed by the digital analog converter (8) and the amplifier (9),
• wherein the inverse Fourier Transforms of said at least two sets of scrambled data are determined from real and imaginary parts of at least one complex inverse Fourier Transform (IFFTc, 25).