[TriLUG] OT: PAM / QAM (was: Home Depot CAT-5)

[Jim Ray]

> Just be sure to not get that "PAM" on your hands as you climb down a
> ladder or your feet walking around your attic.  :-)

[JR>] agreed.  Failure to heed call can produce disasterous results.

> PAM (Pulse Amplitude Modulation) is pretty crude signalling that has
> been used for years, at least as far back as ISDN and certainly before
> then.  If you've ever seen what is involved in ADSL or VDSL (QAM),
> you're really impressed at the level of DSP horsepower required,
> especially on the frequency overlapping technologies.  Ironically, some
> of these complicated algorithms are done with Turbo codes and huge
> constellations for things like v.90.  Cable modem ASIC guys have a far
> easier job (complexity).
> 
[JR>] I still say real mean use real time technologies like vacuum tubes and
copper.  I do confess to appreciate the ability of DSP to implement FFT for
desired and actual signals and to produce auto equalization of audio
signals.  Of course, all I care about generally happens below 20 kHz :-)