Patent attributes
A DMT modem (40) is disclosed, in which a combined time domain equalizer and per-tone equalizer is applied to a received DMT signal. The combined equalizer includes a first FFT function (44) that is applied to a set of samples in a time-domain signal after the application of a time domain equalizer (42). The first FFT function (44) produces an initial FFT result, that is accumulated with a sliding FFT (46) performed upon difference values in the time domain samples. The sliding FFT results are applied to a per-ton equalizer (48) which applies a set of complex coefficients determined in training of the modem. A simple 1-tap FEQ (50) then can recover the signal. The combined equalizer enables per-tone equalization, in a manner that is compatible with conventional DSL training standards. According to a second embodiment, the per-tone equalization is performed only on selected tones of the multitone signal.
