Brian ... I don't think so ... you see, the telco codec can do the
conversion from 64k-bit data stream to audio with real good fidelity BUT
the conversion from analog to digital is a whole different animal (so to
speak). The problem lies not in the mu-law codec conversion (which is
pretty good by the way) but in the signal processing prior to the analog
input to the codec. The filters are passive in nature and are configured
to be low-pass (dropping the signal off at around 4000-Hz) and there is no
real noise (as in pops and snaps and all the other nasties) filtering.
Given the filtering senario at the telco it's a wonder sometimes that
people can get 33.6 connects. The X2 and 56K flex technologies work
(downlink only) by virtue of the Digital Signal Processors contained within
the modems. The software performs dynamic filtering and can provide a
"cleaner" signal to the conversion software than the filters at the telco
can provide to the mu-law codecs. If the filtering at the telco was as
good as at the modems then we would have 56K uplink and downlink speeds (
or at least close to it ).
gm...