bill c. -- QPSK & QAM-16
>>"IEEE has chosen QPSK and QAM-16 as the upstream modulation formats,
and MCNS (of which Cable Labs is a part) will likely choose QPSK, when
they announce the upstream spec at the Western Cable Show. Almost all,
if not all, cable modems in trial now use some form of QPSK for the
upstream."<<<<
It was a long bloody battle, QAM-16 proponets, fought stong for a mandantory single modulation format. I have the complete text from this old March release if anyone wants to see part of the battle: a few quotes were:
"
Matt Brandt made the following motion:
"Move that QAM 16 be mandatory base constellation scheme for the upstream channel" The motion was seconded by V. Hou
In discussing the motion Ivan Reed suggested changing the word mandatory to optional. Frank Koperda suggested that the text should include both QPSK and QAM.
Matt did not agree to the proposed changes.
John Bingham commented that such a motion is immature since there is an ongoing study working on advance PHY.
Matt replies that we will deal with multicarrier issues later, the issue at hand is SC.
H. Samueli commented that one gets QAM for free and will be included in the transmitter chip. To that C. Sierens noted that QAM does not come free because one needs to add equalizers and also add design
complexity. "
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
This goes on & on & on..
bill c - Robs info, is the first I've read on the final results, thanx.
It's still us against QAM, the best technology will prove itself in the end.
For Twisted-Pair VDSL, I sure would like to see the latest precedings,
Hello is there any body out there?
I realize of course that a VDSL standard could drag on till next Christmas. Although I'm happy to see ADSL will be deploying all over the world, by the time they finish work on 56Kbps standard.
Lot's of team work :))
JW@KSC |
