Slowly but surely, my X-10 RF reception is being knocked out by endless
streams of these commands broadcast on different days at different times.
M2 OFFs
C2 OFFs
Gxx DIMs
At first, when only C2 OFFs appeared, I searched in vain for a stuck
transmitter button or some other internal cause. I could find none. The
problem occurred with TM751's, the WGL all-house code unit and with RR501's,
too. Setting the WGL to ignore those three housecodes was all but useless -
the constant strong signal overwhelmed any X-10 transmitter not within a
foot or less of the transceiver. This interference started out slowly over
time, and now forces me to shutdown the RF section of my X-10 system almost
daily.
I'm in the Washington, DC area. Has anyone else seen anything similar? Any
ideas where to look for the transmission source. Could the RF signal "ride"
the powerlines that an X-10 transmitter could receive? Even putting the
receiver in a metal coffee can doesn't seem to point to a potential source
of the signal. It seems to be very uniformly distributed throughout the
house. If I can't get it to stop, I'll have to hardwire a lot of things I'd
rather not. )-:
TIA for any help.
--
Bobby G.
Hi,
Maybe you are getting RFI from other RF source nearby?
If you could capture the raw RF signal using the techniques shown on
my website it might help identify the source.
http://davehouston.org/learn.htm
Who supplies your electricity? Have they recently installed new meters
that can be read remotely? I've seen a few reports of problems from
some metering systems although nothing similar to what you are
experiencing.
Is there any pattern as to when it occurs?
Back in the late 1980's I was working and living in the country of
Californiastan when the community I was in at the time started having
problems with their electric garage doors opening and closing as if
possessed by some evil door opener. It turned out that the US Navy
was testing the big search radars on some ships in the bay. Those big
powerful radars were producing an RF harmonic signal that was just right
to screw with the RF remote controls for a lot of openers. :-)
TDD
http://davehouston.org/learn.htm
I will look into that. I assume I'll need one of these:
<<Radiotronix RCR-315-RP (Mouser P/N 509-RCR-315-RP) which can be tuned to
cover approximately 300-330MHz>>
and that I am looking for signal in the 315MHz range. One odd thing I have
noticed. When these waves of commands hit, Jeff Volp's XTBM meter shows the
frequency of the signal as lower that 100Khz which I thought odd since it
only happens when an RF transceiver is on line. Why would RF noise show up
as a lower than normal frequency signal being output to the powerline?
<Who supplies your electricity? Have they recently installed new meters
that can be read remotely?>
No, but now that you mention it, they have instituted a program where you
can save $160 by letting them install a box on your CAC that allows them to
shut it off in a brownout. I had never thought of that correlation before
because the timing seemed so random but it could be that the signals appear
whenever they want to turn off people's AC. FWIW, it's in the 70's today
and there's no interference. Geez, I hope you're wrong but I think you're
right. If they wanted to make sure those AC's stayed off, they would just
transmit an OFF signal while the brownout lasted although you'd think one
command would suffice.
It came on before the hurricane and stayed on throughout the event (at least
for the time I had power). I will have to scan through my Homevision logs
and extract the durations and occurrences of these events. They did show up
shortly after I got my first "sign up" postcard.
If that's the source of the signal, could it be RF carried over the
powerline at 315MHz? My understanding of the X-10 whole house filter is
that I might be able to stop powerline infiltration of such a control
signal, but RF's going to require *their* cooperations.
<<I've seen a few reports of problems from some metering systems although
nothing similar to what you are experiencing.>>
I've been searching Google for quite some time and no one seems to be having
these particular problems. But I *know* there are a lot of X-10 users in
the DC area. If it's system-wide, someone else has to be seeing this. Five
different RF transceivers all show the same symptoms. Endless streams of
the same commands.
<<Is there any pattern as to when it occurs?>>
I will have to examine my Homevision log files to give you an answer. I've
now got the RF powerline coupler plugged into an appliance module that I
shut down whenever I detect a runaway stream of RF. But it's mighty
inconvenient and doesn't tell me exactly how long the storm lasts. But it
does tell me when it begins. I may be tempted to set up a line voltage
monitor to see if I can correlate the runaway commands with any potential
brownout conditions.
What do you think my chances of getting to someone at Pepco who has any idea
what I am talking about are?
Thanks for the input, Dave. Hope all as well as can be hoped for.
I guess I'll start logfile processing. X-10, the electronics detective's
hobby.
BTW, is there a suitable RF unit I can scavenge from a X10 transceiver? I
think I have at least a dozen assorted TM751's and quite a few RR501s and a
coupla CM15As that are not in use or likely to be.
I assume it will take an oscilloscope to see if the signal is actually
coming through the powerline or is being broadcast from local transmitters.
I have a slight fear that if I ask the power company anything about it,
they'll think I want to jam or defeat the signal and turn me in to Homeland
Security. Hey, stranger things have happened! (-:
FWIW, here are the binary representation of the three unwanted commands:
C2 OFF 01000000 00110000
M2 OFF 00000000 00110000
G DIM 005 10100000 10011000
C2 and M2 off differ by one bit. G Dim XX by slightly more.
--
Bobby G.
<stuff snipped>
>
> Back in the late 1980's I was working and living in the country of
> Californiastan when the community I was in at the time started having
> problems with their electric garage doors opening and closing as if
> possessed by some evil door opener. It turned out that the US Navy
> was testing the big search radars on some ships in the bay. Those big
> powerful radars were producing an RF harmonic signal that was just right
> to screw with the RF remote controls for a lot of openers. :-)
Yes, I was aware of them. Lutron's Radio RA system had to add a second RF
channel in NYC because of interference from a source that wasn't going away.
Read: government.
We just had a round of that a few years ago near DC at Andrews AFB and
others in Denver had the same problem. I know that two military research
labs nearby (I live between the two on almost a perfect straight line are
tasked with IED jammer development so I wouldn't be surprised if the signal
correlated with elevated threat levels. The DC area is as the Pentagon says
"target rich environment."
But in reality I think Dave is probably onto the real source: The local
power company has just instituted a program where they hook a receiver/relay
between your AC and the powerline. In brownouts, they can shut your AC off
remotely. I was going to apply for it because we don't use our CAC anymore
and have switched to window ACs, but that seemed to be cheating so I decided
not to.
The "blips" started appearing a month or two ago, when summer began. They
are not there today, with the temps in the cool, dry 70's (the benefit of a
hurricane - wonderful, cool, clean air for a day or afterwards). Now I have
to download some temperature data and try to correlate that with the times
the bogies appear in my Homevision log file (records all externally
generated commands to log file). The days of endless bogies generate huge
log files, 100 to 1000 times the normal size.
--
Bobby G.
It's unlikely but possible that it's coming in via the powerlines.
Your reading with Jeff Volp's device is _probably_ reporting the
translated PLC command although I cannot think of a reason for the
lower frequency. The transceivers tend to have very wide RF bandwidth
and PLC receivers do as well, usually reacting to signals in the
75-200kHz range. There was something a few years back, which I dubbed
the "Endless Dim Syndrome" where the valid 120kHz was being radiated
by the in-wall wiring and inductively coupling to TM751s (mostly) via
their antenna. It was fairly easy to induce by aligning the antenna
with the wiring. However, only Dims & Brights were reported by the
victims. The TM751 was apparently cheating, assuming that any further
RF meant the remote was still sending and the poor design of the RF
receiver allowed it to respond to the lower frequency. Recent TM751s
use the same high-quality RF receiver used by the CM15A but I have no
idea when that change occured.
You can steal the RF receiver daughterboard from a TM751 but I'm not
sure I recall the connections. The RF receiver daughterboard in the
CM15A is much better but I'd hate to see you cannibalize a CM15A. The
315MHz receiver is the one, should you go that way - turn the tuning
slug 1/8T CCW and you'll be close enough.
You should be able to find a freeware/shareware oscilloscope program
that uses the soundcard. It's easier than the methods in my article
which was written long ago.
The decoded bits don't tell me what I want to know. It may be that the
codes are actually longer and the X-10 receivers are just grabbing the
first 32 bits - I never thought to test whether that was possible.
But, if the codes are longer, we can possibly rule out an X-10 source
(some X-10 security codes are longer). Of course, X-10's limited range
probably rules out a nearby source. X-10 uses NEC's IR code which
dates back 40+ years and has been copied with slight modifications by
many others. I haven't encountered any others using it for RF but I've
been occupied elsewhere (several surgeries and other hospitalizations)
over the past 18 months or so. We might learn something from the raw
codes. And, if it is a high-power source, it may just be overwhelming
the receivers as those military tests a few years back did to the
garage doors which normally only respond to rolling codes (different
with each transmission).
Pepco is unlikely to be helpful unless you reach the right person.
Duke's regional engineer came to investigate an issue I had a couple
of years ago and he was quite sharp but the ones I talked to before he
came by were clueless.
IIRC, some folks on the West Coast were having some X-10 issues with a
specific smart electric meter. I don't recall details. I think there
was a discussion (with Jeff Volp's participation) on the X-10
Community Forums. Duke Energy installed Excellon meters here a couple
of years back. I've seen no X-10 issues but have had two (different
brand) inexpensive 700W microwaves lose their minds - beeping randomly
and flashing or clearing the displays. I've suspected the new smart
meters might have been outputting something that got by any filters
the microwaves might have had. I now have a 1000W Haier Grill/
Convection/Microwave combo that seems immune (so far).
I'm an old broadcast engineer/two way radio tech and I had to track down
RF interference all the time. My friend who worked for the local
power company as an electrical engineer in charge of their
communications told me that back in the 1970's they were tracking down
a lot of RF interference caused by doorbell transformers. I have an
idea that today's proliferation of "Wall Warts" could be responsible
for a lot of RF and power line borne interference. It's something to
consider.
TDD
You need a specialst in Electromagnetic Compatibility (EMC) There is
an IEEE EMC chapter in DC/Northern Virginia that has experts in
tracking down your problem. Try contacting Mike Violette and see if
he knows of someone who lives close to wherever you live. Please tell
him that aI referred you to him. If Mike can't help you, you might
try to find an amatuer radio operator who lives nearby, they are also
good at tracking down stray radio signals.
WASHINGTON / NORTHERN VIRGINIA IEEE EMC Society Chapter Chairman
Term: 1-1-2008, 12-31-2011
Mike Violette
Washington Labs Ltd
7560 Lindbergh Dr.
Gaithersburg MD 20879-5414
Phone: +1 301-417-0220
Fax: +1 301-417-9069
mi...@wll.com
traced to my new remote control motion detector lamp. it was junk
quality i tossed it in the trash
put a offending XM on a UPS, see if its still spazing, then unplug
from line, and check again.
if it spazes on a unplugged UPS you know its radio interference.
a local ham club radio amatuers may be happy to help you find the cause
I don't know xm10 all that well. Seems like it never really took
off. There isn't a unit id in the command stream? How does each unit
know it's the target?
Doorbell transformers sound really bizarre as a source of RF. Somebody
at a.h.r tracked down a source that says it is from contacts that
disconnect the transformer when the current is too high for a class 2
(limited energy) transformer. (Or something like that.) Contacts would
repeatedly open (with arcing) and close.
My guess is that class 2 AC-out wall warts are "impedance protected",
which most doorbell transformers probably are now. At too high a current
the voltage just droops.
My guess is that DC wall warts are the same, or the DC side has a
current limit circuit. Are they switch-mode these days? Wouldn't think
switch-mode would be worse than other switch-mode power supplies found
all over the place.
The transistion from transformer to switched has mostly happened but
there are a lot of existing transformer ones floating around still in
use. I like the switched ones because most work on anything from 100
to 240vac. Sure makes travel easier.
They will "heal" themselves and then start again later.
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"Robert Green" wrote in message news:j3g6ej$kko$2...@dont-email.me...
I've had immemse interference from certain CFL bulbs.