Re: ESM1 X-10 Broadcast storm detector cradle

["Robert Green" <ROBERT_GREEN1963@xxxxxxxxx>]

"Neil Cherry" <njc@xxxxxxxxxxx> wrote in message

> On Sun, 26 Aug 2007 10:42:11 -0400, Robert Green wrote:
> > Jeff Volp and I have been discussing, in another thread, the
construction of
> > a docking cradle for the Elk ESM1 model X-10 power line meter that would
> > detect "broadcast storms" of X-10 signals.  These storms are typically
> > created by stuck transmitter buttons and stand-alone controllers like
the
> > CM11A running wild.  When a broadcast storm occurs, the household lights
and
> > X-10 devices are typically frozen in their current state and cannot be
> > changed remotely.  These storms, at least in my house, have a very low
SAF,
> > especially if they occur during a critical time, like when someone's
late
> > for work.
>
> I've trimmed the idea of using a 555 circuit (that would work). Have
> you considered using a small microcontroller chip? One that requires
> no external components? Perhaps a PIC 12F chip? They're small, 8 pin
> (Vcc, Gnd, 5 in, 1 out) and the external relay or maybe an opto chip
> to separate the ESM1/CPU and external relay setup? The hardware is simpler
> but now you've added software.

I selected the 555 for two reasons.  First, I've built primitive darkroom
timing equipment before so I'm familiar with it. The second you covered with
your last 4 words!  It doesn't get much simpler than the 555.  If I didn't
have the X-10 sensing smarts built-into the ESM1 then a microcontroller
would absolutely be the way to go.  My rig is merely a reporting device,
giving me the ability to act on the information produced by the ESM1.
However, if you're willing to show me how a PIC could do it better, I'd more
than willing to listen and learn!

> Not sure why you're not using the HA system to determine that you've
> got a storm.

For a couple of reasons, but primarily because the controller might well BE
the source of the storm, especially if it's an Ocelot and I've written the
code! (-;  But there are other reasons and one involves locating the runaway
transmitter.  Tracking down the offender *should* become very easy once the
cradle's operational and alert sounds as soon as storm starts.  Most of the
storms here lately have been of the "heavy object placed on a face up
Palmpad" variety, which an immediate alert tone should quickly cure.  There
are always pesky exceptions, though, and in reviewing past storms, there are
situations like a runaway CM11A where an alert might not help much.

The typical hunt for a stuck button or whacked out CM11A goes like this:  I
go from room to room with the Monterey, a TM751 and a PalmPad in tow, taking
readings and examining and unplugging transmitters and various electronics.
It's not very efficient so I decided there had to be a better way. What I
needed was a way to get readings of the X-10 signal strength on the various
branch circuits from a single location.

The ESM1 runs from a wall wart and doesn't plug in directly to the wall like
the Monterey analyzer. The X-10 signal enters the meter head in a low
voltage format.   That enables me to place similar wall warts on the major
branch circuits throughout the house and feed those signals through a rotary
switch to the ESM1 head.  I might have to account for some signal
attenuation on the longer runs, but I should be able to quickly locate the
source of the storm by examining the signal on each branch circuit.  That
should be pretty simple to accomplish either using a rotary switch or a
stepper relay.

I'll probably mount the meter head near the circuit breaker panel so as a
last resort I can switch circuits off from the panel to see which circuit is
powering the runaway transmitter.  I hate having to work the breakers like
that since the great "Third Watch Series Finale Disaster" where I blitted
out the VCR programming for the very last episode by jacking circuits on and
off at the panel (that VCR's since been replaced with one that doesn't lose
its mind when power "blinked").  I'd been planning to do this for quite some
time and the addition of a "storm detection" function has given me the
"kick" needed to actually build the sucker.  There are two reasons to build
the device, now, not just one.

> You already have the controller and software. The same
> signal in x seconds usually means storm.

I could, and probably will, use that option as a confirmation that the ESM1
cradle is working properly.  More importantly, broadcast storms don't
necessarily consist of strings of valid X-10 commands.  Plugging in a device
like a new baby monitor would trigger the ESM1/cradle device while it would
probably just knock out any X-10 based controller.  I'm sure a PIC-slinger
or a C-Max wizard could detect a noise storm pretty easily, but for the
moment, I'm more comfortable relying on Elk's firmware gurus to give me
information about the type of signal causing the storm in convenient
binary/optical format.

I'm not sure how Jeff's XTB device will react to strong noise at 120KHz but
I know that the ESM1 will continuously light a bargraph segment if the noise
is strong enough.  With photodiodes placed up against the meter faceplate,
I can detect and react to that information.  And even if I don't string a
lot of wall warts to feed into the remote head, I can at least have one on
each phase and that will provide information about the state of the phase
coupling.

> Just a thought. :-)

And a good one.  Thanks!  I just realized I can do all this with my GVX MUX.
It has a programmable motion grid so all I have to do is feed it the image
of the ESM1 faceplate to the MUX so I can close alarm contacts if motion is
detected for more that X seconds in the grid square that covers the LED
areas.  I'm assuming that an area going from light to dark is going to
trigger the CCTV's motion sensing circuitry, but I suppose I should check to
make sure.  No . . . wait . . . I'm getting too far from the basic premise.
I need a runaway design detector! (-:

I'll stick with the 555 based design; too much complexity in the MUX unit
itself but it sure shows there's more than one way to scan a 'cast.  (-:

It would probably be more useful to people who don't own ESM1's to be able
to build a broadcast storm detector out of an unused lamp or chime module,
but people who rely on X-10 really *should* own at least an ESM1 or similar
meter.  The cradle makes the ESM1 useful 24 by 7 instead of on an ad-hoc
basis.

--
Bobby G.