2 ms·

I'm almost certain that modern ADSL variants employ up to at least 32768-QAM.

• dfox 3y ago
  Modern ADSL and VDSL version typically use DMT, which is more or less the same thing as OFDM. Interesting part of that in context of xDSL is that each of the subcarriers (typically QAM-64 modulated) can have different amount of actual payload data assigned to them depending on the loop quality and interference (many xDSL CPEs have spectrogram somewhere in their web interface which directly shows how the payload is distributed over the subcarriers).