The pulse train of a signal is modulated by a DPIM modulation involving a discrete random time parameter. A first processing is performed on the signal to deliver a sampled signal. A second processing is performed on the sampled signal, comprising a correlation processing including at least one elementary correlation processing with a correlation mask corresponding to the shape of at least part of a sampled pulse, and delivering second information items. A third processing is performed for detecting the pulses following a first pulse by taking account of the position of the first pulse, on packets of second information items, which are separated by a duration related to the discrete random parameter.