Abstract: Seismic impulses irregularly distributed in time (according to a random or a pseudorandom code for example) are transmitted into the soil, and the direct waves and those reflected by the subsoil discontinuities are picked-up by a reception system (G). The frequency spectrum of the emitted and the received signals is divided into several bands, and the components of the signals in each one of the bands are reduced to elementary signals indicating the change of sign thereof (sign bit) and are recorded. Cross-correlation of the elementary signals respectively associated with the emitted and the received signals and stacking of the cross-correlation products associated with each sensor are carried out thereafter for each sensor of the reception system, and seismic sections very comparable to what would be obtained by digitizing the signals received with full precision, as in conventional methods, are achieved with the obtained stacks.