The invention relates to a method for more precisely characterizing an electrical system by impedance spectrometry. The method consists of applying an input signal to the electrical system that comprises a sequence of sinusoidal perturbations, so as to scan a primary series (A) of frequencies; measuring an output signal of the electrical system in response to the input signal for each of the applied perturbations; and estimating a characteristic size of the impedance of the electrical system for each of the applied perturbations; wherein the perturbations of the sequence are applied so as to scan, turn by turn, a plurality of sub-series (A1, . . . , An) of frequencies resulting from the primary series (A), each sub-series of the plurality being interlaced with at least one other sub-series of the same plurality.