PMG,
if you take a plain pair of copper, you can transmit ADSL over it. Since DT owns the copper, they can do it.
The lower end of the total spectrum of ADSL is reserved for POTS (plain old telephone service). That means, on the network side you mix the data (e.g. Internet traffic) and POTS on the copper line, and at the customer premises you use a POTS splitter to seperate them again (e.g. one line to your computer, one to your phone).
The spectrum of ISDN is somewhat higher than ADSL, and it overlaps with the data range. Therefore, there are some solutions out there, which squeeze the data range in the upper area of the spectrum to make space for ISDN. Then you can transport ISDN over ADSL (I gues this way around is more correct than ADSL over ISDN), but the smaller space for the data spectrum results in shorter distance or speed.
I know Orckit has a solution for ISDN over ADSL. Other people on this thread will know better about Amati, they're probably working on it. I don't know either if or when the ISDN transport will be included in the standard.
Look at adsl.com for more info.
I don't know your formula, but my practical experience says that 6km at 2M are extremely unlikely to achieve in the first round of modems.
Hope that helps.
Arndt |
