Re: Interesting Concept... or complete idiocy?

["K. C. Li" <li@xxxxxxx>]

On Wed, 20 Feb 2002, Ian Lowe wrote:

> I figure if I used a large resistor to limit the current, and used
some
> circuit arrangement to "crop" the powerline
"signal" so that I was only
> looking at the segment from -10 to +10 I would be able to do some
simple DSP
> on the line to watch for firstly, the zero cross, then a pulse of
"something
> kinda like 120khz" in the right place.

Apart from the ADC part, that is how Leviton and X-10 Pro implemented
their receivers to try and improve on the sensitivity and noise rejection.
I quote from the Leviton documentation regarding their
"Intellisense"
feature:

"Leviton DHC devices use Intellisense, a special gated-type of AGC, to
help eliminate noise problems. This circuit feature is ideal for powerline
carrier systems because it only operates during the signal window when
receivers listen for command signals. Noise levels in the signal window
are never as high as they are during other portions of the AC power curve.
Therefore, Leviton's Intellisense gated AGC will desensitize a receiver to
noise signals with only a minimal reduction in command signal sensitivity.
The result: Problems from noise interference are dramatically reduced
without affecting overall system performance."

Regards,

Kwong Li
li@xxxxxxx
Laser Business Systems Ltd.
http://www.laser.com