There was an article in October Internet World "Enter ADSL" that
addresses the issue, an extract,...
<< In May, three RBOCs requested that ANSI change the ADSL standards
to include CAP parameters. Regardless of whether ANSI changes the
standard, telcos can choose whichever technology they prefer.
The characteristics of CAP are the same as the QAM standard for
regular modems. The CAP system works on two channels. If they are
asymmetrical, there is one large channel to download information and a
smaller one for uploading.
The DMT spectrum is divided into 256 4-KHz carriers. A variable
number of bits is loaded onto each carrier independently. Thus, there
are many channels and the technology appears to be more flexible as a
result.
DMT prototype transceivers have shown high transmission speeds,
simplicity, reliability, and good line noise characteristics. DMT
appears to be faster than CAP at distances both close to, and farther
from, the central switch. DMT also seems to be more robust, capable of
handling shortcomings in the phone network.>>
I would recommend reading the whole article. The complete URL is:
pubs.iworld.com
PS. I recommend using Control C and Control V rather than retyping it
(grin) or you can go to: http:www.iw.com and search on "Enter ADSL"
and get a long list of articles
Regards,
Jim |
