Re: X10 AGC and Insteon

[nobody@xxxxxxxxxxxx (Dave Houston)]

I would sample outside the X-10 and Insteon windows. Any noise that's likely
to be troublesome is likely to be present outside these windows. Basing your
threshold on the general background noise level makes more sense to me than
the "gated AGC" that others use.

However, it might be a problem should someone encounter another system using
the powerlines outside of the X-10 & Insteon windows.

If you haven't already done so, you might explore how X-10 does it with the
CM15A.


"Jeff Volp" <JeffVolp@xxxxxxx> wrote:

>I'm working on adding AGC to the XTB-II TW523 emulation mode.  The XTB-II
>fully error checks all incoming messages, and sufficient noise can cause
>messages to be rejected.  Since the XTB-II can recognize X10 signals down to
>the sub 10 mV region, continuous background noise can be a problem.
>
>All X10 data is transmitted with its compliment.  Only half the sample
>windows should contain a X10 signal burst (neglecting the 1110 start
>pattern).  So a simple means of detecting noise is to look for pulses in
>every sample window.  More than a couple of counts (caused by random
>glitches) in every window would mean the presence of background noise, and
>the sample threshold should be increased.
>
>This appears to work well in an X10 environment.  However, Insteon
>transmissions will cause a problem.  They appear as noise to X10 because
>they appear in every X10 sample window.  Once the Insteon signal goes away,
>the threshold will recover.  However, a low-level X10 command closely
>following an Insteon command could be missed.
>
>There are a couple of ways to deal with this, and I'd like your opinions.
>One is to speed up the recovery rate so the threshold decreases more
>rapidly.  Another is to sample for noise at a position other than where the
>Insteon signal can appear.  Unfortunately, that means noise appearing in the
>X10 sample window would be ignored.  Or, maybe this won't be a problem at
>all, and can be ignored.  Comments?
>
>Jeff
>


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