solarwind wrote:
> I've been doing some reading and research on how the analog phone
> signal + the dc power + ADSL signals all work (on a electronics &
> signals level) on the same set of copper wires. I've come across this
> document: http://www.epanorama.net/documents/telecom/adsl_filter.html
> and have a few questions.
>
> * First question. How does this work? How do the signals NOT interfere
> with each other on the line?
>
>   
Because they use different frequency bands (with quite a big gap between 
them) and then filters are placed on the phone gear to keep the high 
frequency ADSL stuff away from it.
> * It appears that my phone line has only two wires. Is this a twisted
> pair? I'm guessing not because I don't see a third ground line.
>   
It is generally a twisted pair but typically not a particulally tightly 
twisted one. Some older phone wiring and a lot of cheap extentions are 
not twisted
> * If it's not twisted pair, how is ADSL able to operate at such high
> speeds (10 mbit/s) reliably?
>   
Multi-level encodings, a lot of carefully designed error correction 
codes, splitting into narrow frequency bands so if one band is bad it 
doesn't matter too much and the ability to adapt encoding details to the 
condition of the line .

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