US Patent 7327765 Home phone line networking next generation enhancements

New version devices of a home phone line network may operate on a first carrier frequency (within the new version frequency band) while old version devices may operate at a second carrier frequency (within the old version frequency band). Preamble, header, and trailer portions of a new version signal include a plurality of spectral copies of a baseband modulated signal. One or more of these spectral copies of the baseband modulated signal is/are indistinguishable from corresponding components of an old version signal. The new version signal is transmit filtered to have a negatively sloping power spectral density in order to maintain a constant power level in relation to old version signals and to have slope that is opposite of binder crosstalk so as to form, with the average crosstalk, a constant level white noise floor.