A system including at least one processor, said processor configured to perform for a power spectral density where k indexes subchannels of a multitone system, for each subchannel k: adjusting transmit power by changing a power spectral density for each subchannel k to the minimum of a power spectral density and a maximum of a reference power spectral density REFPSD(k)=min(NOMPSD(k), NOMPSD???PCB)