Re: Cause of some major X10 problems found

[nobody@xxxxxxxxxxxx (Dave Houston)]

"Robert Green" <ROBERT_GREEN1963@xxxxxxxxx> wrote:

>Are we certain that Bruce's setup actually uses the TW523?  I thought he was
>using the XTB-II in the TW523 emulation mode.  I don't think it's relevant,
>though because I don't believe it's the culprit in any way.  What does the
>TW523 report to the log when it only sees a single frame of the two in each
>X-10 command?  That could have some bearing on whether a noise-created
>command is ever logged.  Distance to the source of the signal could also
>effect that.  Jeff can probably explain how the XTB-II reacts to orphaned
>single frame commands.

Yes, Bruce is using a TW523. The TW523 doesn't log anything but merely
outputs the codes on a delayed basis and with gaps when there are contiguous
codes. The controller has to do the logging. The controller can only work
with what the TW523 gives it.

>I would hesitate to say "no way" because that's what we're talking about
>here: Very unlikely, but still non-zero probabilities.   Since Jeff has
>actually observed such beasts in the wild, I'd say we're closer now to "way"
>then we were to "no way" before he made his observations.  It's only until
>he gets his hands on Bruce's Bad Boy PS that I would feel comfortable in
>concluding there's "no way" such a supply could not generate a noise that an
>X-10 switch would react to as good code.  I'm even more certain that such a
>flakey PS could seriously corrupt any valid X-10 codes transmitted while
>it's putting noise on the line.

Jeff said he observed one such beast. He did not indicate the nature of the
beast (i.e. what code).

>When doing PC tech support work for several hundred very technically
>inclined users I would often find myself saying "There's no way for what you
>are describing to happen" when responding to the trouble call only to go to
>their offices and find out that their PC was indeed displaying an upside
>image or whatever other bizarre condition they were reporting.  That's why I
>am reluctant to discount the numerous reports we've seen over the years of
>phantom activations.

>Actually, I believe that the laws of probability are being very accurately
>represented by what we're seeing.  The odds of creating lots of simply
>random noise are quite high.  The odds of creating noise that the Monterey
>reports as BSC's - the right start pattern followed by garbage - are much
>lower.  The odds of creating a valid code out of random bits are very, very
>much lower.  But I don't believe they equal zero and that's based on the
>reports we see of lone activations in the middle of the night.  Based on the
>X-10 propagation speed, and the length of a day, the occurrence rate might
>be one in 10,000 or even 100,000.  I feel that sort of "once a day"
>probablity lines up better with the random code generation theory than the
>Bloom theory, which should have lights turning on faster than one could turn
>them off.

If you mean once every 100,000 years, I agree.

>Maybe the light switches that are misbehaving don't know the theory of one's
>complements.  (-:  It will be interesting to see what happens when Bruce
>sends his PS out to you guys for analysis.

The fact that grounding the pin fixed the problem rules out that the switch
was reacting to some aberrant PLC pattern that would not be reported by an
X-10 interface. Nor is there any reason to believe that X-10 would have
designed switches and modules that responded to patterns that would not be
reported by interfaces designed by the same people.

Analyze away but count me out - I haven't been on a snipe hunt in over 60
years.