Re: satisfied customer

[Dory Ethan Leifer <leifer@terminator.rs.itd.umich.edu>]

  > W. Curtiss Priest wrote:
  > > 
  > > Matthew Sparby said, regarding ISDN:
  > > >It doesn't do any modulation at all
  > > 
  > > My communication theory is rusty, but I thought that certain phase shift
  > > encoding schemes were inherently more noise immune and better reached
  > > toward the theoretical limits of the bandwidth available than simply
  > > sending a "digital signal" (a simple rise and fall in voltage on a
  > > wire).
  
  I think there may be a bit of confusion over "analog". In many cases,
  for the reasons mentioned above, digital signals are modulated to make
  them analog. If a user sends analog information over this type of digital
  carrier, you get analog --> digital ---> encoded analog. Higher speed
  links for ADSL, for example, do use complex analog encoding techniques
  to carry digital information. Clearly ISDN U-loops are not running near
  theoretical limits as can ADSL.  Dory