Device for emitting-receiving signals in two symmetrical frequency bands in relation to a first frequency FCA and such that each one of the bands comprises symmetrical channels in relation to second frequencies FCLA, FCUA, comprising: a first circuitry generating a signal of frequency FA, a signal of frequency FB=FA/N1, a signal of frequency F1=|FCA−FCLA| and a periodic signal of frequency F2 equal to the difference between a central frequency of one of the channels and the associated second frequency, and wherein FA=N1·(FCLA+F1)/(N1+1); a second circuitry able to carry out non-linear operations between the signals of frequencies FA and F1 and those of frequencies FB and F2, generating multitone signals comprising the frequencies FA−F1, FA+F1, FB−F2 and FB+F2.