Abstract: The present invention relates to an imaging method including the following steps—successively transmitting first and second waves in response to the successive application of first and second electrical excitation signals in separate first and second frequency bands contained in a range of excitation frequencies of the transmitter/receiver, receiving and converting respective first and second acoustic or electromagnetic echoes into respective first and second electrical reception signals, —digitising (100) the first and second electrical reception signals, —mixing (200) the first and second digital signals at different demodulation frequencies, —filtering (300) the first and second demodulated signals, —decimating (400) the first and second filtered signals.