RE: Interesting Concept... or complete idiocy?

["Stuart Whyte" <lists@xxxxxxx>]

Alan,

 

Have you looked into building one of these??  Any ideas of approx cost?

 

Cheers

 

Stuart

-----Original Message-----
From: Alan Shields [mailto:alan@xxxxxxx]
Sent: 20 February 2002 20:03
To: ukha_d@xxxxxxxSubject: Re: [ukha_d] Interesting Concept... or complete idiocy?

take a look
at
http://www.cix.co.uk/~pplunkett/x10.htm

Alan
Shields
alan@xxxxxxx
On Wednesday, February 20, 2002, at
06:34 pm, Ian Lowe wrote:

> I am fishing for the views of experts before
> comitting time to something
> that's obviouslly flawed.
>
> As I
> understand it, X-10 signalling is basically this:
>
> You place (and
> detect) a 1ms wide pulse of 120khz with an amplitude of as
> little as .1v
> 20ms or so after the zero crossing, such that after an agreed
> pre-amble,
> a
> burst means "1" and no burst means "0" this transmits house
> code, unit
> code, command a couple of times for redundancy.
>
> Now, I saw some
> articles about improving X-10 range and reliability, which
> all centred
> around improving how accurately the reciever circuit was tuned
> to
> 120khz,
> and this got me thinking..
>
> It started as "what if the 120khz
> oscillator
> was *very* precise?" I figured
> a PIC Chip with an XTAL clock could be
> that
> precise, and then I figured, why
> bother?
>
> Why not just use the ADC
> in
> the PIC chip to analyse the powerline as an
> analog signal, and watch for
> a
> burst of "noise" in the right place on the
> wave?
>
> 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
> for firstly, the zero cross, then a pulse of "something
> kinda like
> 120khz"
> in the right place.
>
> As i recall, if you want to recognise (and
> replicate) a signal, your sample
> rate needs to be at least double the
> signal rate. so, for a 120khz signal,
> you would want to be sampling at
> 240khz. Given that even the fairly basic
> PIC12C jobs have a 10Mz clock,
> I'm
> sure sampling at 240khz wouldn't be
> stressing things too
> much!
>
> Just
> wondering if you could implement a basic X-10 module with very little
> in
> the way of components?
>
> Does this seem deeply ridiculous? or just
> technically too bothersome? or
> might it even
> work?
>
> Ian.

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