internet over power cables?

[David A. Bandel]

On Wed, 24 Jul 2002 13:38:53 +0800
begin  "m.w.chang" <mwchang at netvigator.com> spewed forth:

> 
> I saw news about china light and power (hk) to offer DSL internet 
> services over electricity acbles. how??? what's the name for that tech?


If you understand how DSL works, you'll realize this isn't far-fetched.

xDSL works by putting a high frequency signal on a line.  Works on a dry
pair (copper with no other current or signal), works on telephone, no
reason why it shouldn't work on power lines (though I'm not sure of the
filtering effect the step-down transformers have).

The only problem becomes isolating the power (filtering the power).  But
you have to use splitters (filters) for xDSL on phone lines.  Same
principal, different voltage/frequency.  With telephone, you're talking 40
volts and audio freqs.  With power you're talking different voltages
(14kv, 220v) at 60 Hz.  If these voltages leak over, they could fry the
modem.  Worse, they could fry the DSLAM (we're talking $20k-120k new).

xDSL's limitation is distance.  5.5km of wire and after that the signal
drops off rapidly.  This is the limitation the DSL manufacturers need to
overcome.

Ciao,

David A. Bandel
-- 
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		-- Nemesis Racing Team motto