Networking DSL/Cabling Issues

[Duane Attaway]

On Wed, 9 Jul 2003, Jonathan Hutchins wrote:

> Quoting Garrett Goebel <garrett at scriptpro.com>: 
>  
> > DSL modem is a misnomer.  
>  
> Yeah, but 99% of the providers and hardware sellers call them that. 

I thought DSL was simply ISDN, but one step further using the analog
component.  When I had ISDN, I noticed the logic transition were indeed
digital at four possible states (compared to two in binary) and were
clocked at 86KHz.  I noticed this high frequency from the telephone
company into my house retained its square shape with almost no distortion.  
That's when I thought it would be too easy for them to modulate magnitudes
of more information using the same frequency, using FM, PSK, or anything
to get more from the lines.  I thought ADSL was the modem version of the
digital switching ISDN.

> It used to be said that a "Modem" was a "MODE EMulator", emulating a digital 
> serial mode connection over an analog line.  As such, a DSL Mode Emulator that 
> Emulates an Ethernet or PPP connection over DSL makes sense.   

ADSL isn't modulated?

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