Cell Relay Archive

["Terry" <terr@sea.com>]

"nobody" <nobody@[127.0.0.1]> skrev i en meddelelse
v57vdn5cdjogf1@corp.supernews.com">news:v57vdn5cdjogf1@corp.supernews.com...
> quoth Terry:
> > I Quote the XDSL-faq:
> >
> > "The scrambler is very important.  It randomizes the signal so an
> > adaptive equalizer in the remote modem can build the inverse channel
> > response (including the transmit filter)."
> >
> > How is this? In what way do the the adaptive equalizer benefit from the
> > signal being scrambled?
>
> Roughly speaking, the adaptive equalizer attempts to cause the received
> power spectrum (after equalization) to be the same as the power sectrum
> that the modulator would produce (before the transmit filter) _if_ the
> data stream was perfectly random.  The actual power spectrum at the
> can be very different from this if the input data are correlated.
>
> If the actual user data were perfectly random, you wouldn't need a
> scrambler.  Since it often is not, a scrambler is needed in order for
> the equalizer to work.
>
> nobody


Ok, does this mean that the reciever assumes that the data sent from the
transmitter are perfectly random, and equalize the channel in regards to the
data being perfectly random. And if its not, then the equalisation would
produce a poor result?

Best Regards
Terry