A system for radio frequency tagging a transmitter of a first useful signal S u, by a second tagging signal C tag comprising configurable time and frequency characteristics, said tagging signal being transmitted simultaneously accompanying the first useful signal S u, said transmitter operating in a communication system or network, in a system having multiple users authorized and adapted to recognize the second tagging signal, said system having at least the following elements: signal generation means (20, 21, 22) adapted to: - produce a first useful signal S u in a given frequency band B, at a frequency fsu and an amplitude Asu, and - know at least the values of the band parameter B Su of the first useful signal S u and of the amplitude A Su of the first useful signal S u, which are adapted to determine, from said values, the parameters of the second tagging signal C tag comprising: - a carrier of the second tagging signal C tag, - a band B Ctag of the second tagging signal, - an amplitude A Ctag of the second tagging signal with a signal level X dB lower than the useful signal X = A Ctag /A Su, - time characteristics of the second tagging signal C tag, including: - the modulation characteristics of the second tagging signal: a constellation, a rate R Ctag, a filtering in transmission, - a duration and a repetition period, T Ctag, - a description of its construction over the repetition period T Ctag, a transmission antenna adapted to simultaneously transmit said first useful signal S u and said second tagging signal, the level of which is X dB lower than the first useful signal S u, means for receiving and processing (30, 31, 32) the first useful signal and the second tagging signal, which are adapted to detect and to discriminate the second tagging signal from the first useful signal. signal generation means (20, 21, 22) adapted to: - produce a first useful signal S u in a given frequency band B, at a frequency fsu and an amplitude Asu, and - know at least the values of the band parameter B Su of the first useful signal S u and of the amplitude A Su of the first useful signal S u, which are adapted to determine, from said values, the parameters of the second tagging signal C tag comprising: - a carrier of the second tagging signal C tag, - a band B Ctag of the second tagging signal, - an amplitude A Ctag of the second tagging signal with a signal level X dB lower than the useful signal X = A Ctag /A Su, - time characteristics of the second tagging signal C tag, including: - the modulation characteristics of the second tagging signal: a constellation, a rate R Ctag, a filtering in transmission, - a duration and a repetition period, T Ctag, - a description of its construction over the repetition period T Ctag, - produce a first useful signal S u in a given frequency band B, at a frequency fsu and an amplitude Asu, and - know at least the values of the band parameter B Su of the first useful signal S u and of the amplitude A Su of the first useful signal S u, which are adapted to determine, from said values, the parameters of the second tagging signal C tag comprising: - a carrier of the second tagging signal C tag, - a band B Ctag of the second tagging signal, - an amplitude A Ctag of the second tagging signal with a signal level X dB lower than the useful signal X = A Ctag /A Su, - time characteristics of the second tagging signal C tag, including: - the modulation characteristics of the second tagging signal: a constellation, a rate R Ctag, a filtering in transmission, - a duration and a repetition period, T Ctag, - a description of its construction over the repetition period T Ctag, - the modulation characteristics of the second tagging signal: a constellation, a rate R Ctag, a filtering in transmission, - a duration and a repetition period, T Ctag, - a description of its construction over the repetition period T Ctag, a transmission antenna adapted to simultaneously transmit said first useful signal S u and said second tagging signal, the level of which is X dB lower than the first useful signal S u, means for receiving and processing (30, 31, 32) the first useful signal and the second tagging signal, which are adapted to detect and to discriminate the second tagging signal from the first useful signal.