mystery signal
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Posted by Dave Houston on November 11, 2005, 11:02 am
Please log in for more thread options 'phase' is clear. There are what resemble triac noise bursts approximately 1.6ms after each zero crossing and the 120kHz seems to be in sync with them. I say nearly continuous because the signal is absent on what appear to be random half cycles (again in sync with the triac-like bursts, 1.6ms past ZC). I say 'phase' because while the two circuits seem to have no communication, they are in phase when observed on a scope. My apartment was originally two apartments and there are two meters which might be a factor. The signal is not coming from anything in my place but there are 4 apartments in the building and 4 more in another building across the street which shares the transformer. A random snapshot of 24 half cycles is 101101101110111110110110 with 1 indicating 120kHz presence and 0 its absence. I've been unable to discern any clear pattern other than the OFFs never last beyond a single half cycle. The triac noise pulses have been here for a few years but yesterday was the first time I saw the nearly continuous signal. It blocks X-10. It shows up as noise on my ESM1. Any ideas? | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Posted by Robert Green on November 11, 2005, 1:18 pm
Please log in for more thread options > I'm seeing a nearly continuous 2Vpp 120kHz signal on one 'phase'. The
other
> 'phase' is clear. There are what resemble triac noise bursts approximately
them.
> 1.6ms after each zero crossing and the 120kHz seems to be in sync with >
communication,
> I say nearly continuous because the signal is absent on what appear to be > random half cycles (again in sync with the triac-like bursts, 1.6ms past > ZC). > > I say 'phase' because while the two circuits seem to have no > they are in phase when observed on a scope. My apartment was originally
two
> apartments and there are two meters which might be a factor.
street
> > The signal is not coming from anything in my place but there are 4 > apartments in the building and 4 more in another building across the > which shares the transformer.
cycle.
> > A random snapshot of 24 half cycles is 101101101110111110110110 with 1 > indicating 120kHz presence and 0 its absence. I've been unable to discern > any clear pattern other than the OFFs never last beyond a single half >
the
> The triac noise pulses have been here for a few years but yesterday was > first time I saw the nearly continuous signal. It blocks X-10. It shows up
> as noise on my ESM1. > > Any ideas? Can you determine whether the signal gets stronger as you get closer to the breaker panel? It's probably an external signal, but it would be nice to know for sure. Don't baby monitors and intercoms that work via powerlines put out similar interference? I would assume that an apartment is much more likely to have "neighbor issues" then single family homes just because units are closer together. Are there any hallway outlets that you could check to get a signal level? You might be able to triangulate in on the source that way. Will your neighbors let you poke around their places with an ESM1? This brings up an interesting question. How can an apartment dweller block such signals (assuming they are external) easily without inducing the landlord to modify the breaker panel? Have you checked to see if any of your experimental setups are still on line? Is it possible that some piece of X-10 gear has gone wild and is just sending out random pulses? -- Bobby G. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Posted by Dave Houston on November 11, 2005, 2:23 pm
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[snip] >Can you determine whether the signal gets stronger as you get closer to the
>breaker panel? It's probably an external signal, but it would be nice to >know for sure. > >Don't baby monitors and intercoms that work via powerlines put out similar >interference? I would assume that an apartment is much more likely to have >"neighbor issues" then single family homes just because units are closer >together. Are there any hallway outlets that you could check to get a >signal level? You might be able to triangulate in on the source that way. >Will your neighbors let you poke around their places with an ESM1? > >This brings up an interesting question. How can an apartment dweller block >such signals (assuming they are external) easily without inducing the >landlord to modify the breaker panel? > >Have you checked to see if any of your experimental setups are still on >line? Is it possible that some piece of X-10 gear has gone wild and is just >sending out random pulses? My walker doesn't handle stairs or any but the slightest of grades so... Even if I could get close to the (basement) breaker panel, signal attenuators can cause misleading measurements. I can't navigate to the neighboring apartments. They are upstairs/downstairs from mine. I don't think intercoms or baby monitors output a (somewhat) sporadic signal like this one. Most of those use FM so they output a continuous wave with no interruptions. It seems to be related to the triac-like bursts which have been here for a few years. They (and I) predate all other tenants. There are some automated external lights but I think they are just on a timer. I don't think there is anyway to block external signals except at the breaker panel. I think (but am not certain) its presence on only one 'phase' indicates it's probably not from a source external to the building. The first thing I did was make sure there are no transmitters of any kind plugged into the problem 'phase'. I wish this had shown up while I had the Insteon kit here. It would have been interesting to see how well (or not) it handled it. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Posted by Robert Green on November 11, 2005, 7:58 pm
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<stuff snipped>
> My walker doesn't handle stairs or any but the slightest of grades so...
Troubleshooting X-10 clearly is for the nimble. You've got a troublesome situation. > Even if I could get close to the (basement) breaker panel, signal
> attenuators can cause misleading measurements. In the absence of any leads, it would be the one I would try to follow. It makes me wonder again if I shouldn't try to set up some ESM1's at different points in the house to continuously monitor the signal. It would make it easier to track down such anomalies because you'd at least have some baseline readings from different areas in the house. I recall you once saying that you were never able to reliably detect noise on your ESM1. I assume that wish has been granted in a round-about way. (-: > I can't navigate to the neighboring apartments. They are
upstairs/downstairs
> from mine.
I thought it would be a problem. Yet it's plausible someone plugged in something in one of the other apartments that's generating the interference. > I don't think intercoms or baby monitors output a (somewhat) sporadic
signal
> like this one. Most of those use FM so they output a continuous wave with
no
> interruptions.
I wasn't sure how they functioned. Why would a triac-based device output so randomly? If they're chopping the wave at regular intervals, shouldn't their output be regular as well? > It seems to be related to the triac-like bursts which have been here for a
automated
> few years. They (and I) predate all other tenants. There are some > external lights but I think they are just on a timer.
Have you noticed anything new? CF bulbs in the hallways? > I don't think there is anyway to block external signals except at the
'phase'
> breaker panel. I think (but am not certain) its presence on only one > indicates it's probably not from a source external to the building.
That seems to be a good call. If it was outside, it would pass through the main breakers equally and show up on both phases. I suppose that leaves you with trying to determine whether the interference is 24/7 or whether there's a day/night pattern to it as you might expect to see if lightning was involved. > The first thing I did was make sure there are no transmitters of any kind
> plugged into the problem 'phase'. I was pretty sure you did, but it never hurts to touch on even the obvious. > I wish this had shown up while I had the Insteon kit here. It would have
> been interesting to see how well (or not) it handled it. The Electronic Demons don't work like that. (-: It would be too easy! Have you unplugged stuff on the phase that is exhibiting the problem. The only other thing I can think of is that two transceivers stuck on at the same time causing collisions, but that's so unlikely an event it's hardly even worth considering. Unless someone's paid one of your neighbors to do it -- you do have one or two folks around who would love to see something like this (or worse) happen to you. I've heard of far stranger things done by unhappy newsgroupers! IIRC, you were reporting pretty strong signal voltage of the interference. What kind of levels of X-10 signal do you normally see in your apartment? If it's in the 3-4 volt range it seems like another indicator that it's something in the next apartment because that seems to be about the right level of attenuation. I guess absent any other options, I would execute the "X-10 Unplugging Dance" to make sure that it was nothing in your own apartment that went rogue. I had a X-10 Maxi controller that began spewing loads of garbage onto the line when it failed. That was before I got the Monterey so I can't say for sure what it was outputting but they weren't valid X-10 codes that could be captured by Activehome. All X-10 commands in the immediate vicinity of the failed Maxi wouldn't work - just things at the farthest point from the failed controller. I think I still have it in the junk box. It would be interesting if the Monterey showed a similar output to your noise. My only suggestion at this point is to pretend to be the owner and hire a sparky to filter your apartment at the main breaker. It won't be cheap, though, because of the unusual configuration you have with two feeds from different phases. -- Bobby G. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Posted by Dave Houston on November 12, 2005, 6:52 am
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>Troubleshooting X-10 clearly is for the nimble. You've got a troublesome
>situation. I'm confident I could run this down quickly if my mobility were not so severely restricted. >I wasn't sure how they functioned. Why would a triac-based device output so
>randomly? If they're chopping the wave at regular intervals, shouldn't >their output be regular as well? Powerline intercoms predate X-10. I used them in the early '60s. I'm not sure this signal is from a triac-based device. It appears to be in sync with the triac like switching transients that have been on the line for several years (but which are not coming from any of my devices). The switching transients come ~1.6ms after each ZC. The endpoints of the periods when this signal is absent coincide with the switching transients but the transients are always there even when there is no change in this signal presence/absence. >IIRC, you were reporting pretty strong signal voltage of the interference.
>What kind of levels of X-10 signal do you normally see in your apartment? >If it's in the 3-4 volt range it seems like another indicator that it's >something in the next apartment because that seems to be about the right >level of attenuation. That's not a reliable indicator since some X-10 transmitters output 10Vpp and others 5Vpp. >My only suggestion at this point is to pretend to be the owner and hire a
>sparky to filter your apartment at the main breaker. It won't be cheap, >though, because of the unusual configuration you have with two feeds from >different phases. It's not worth that. I only have one X-10 device that's affected and it's in a walk-in pantry and is not critical. There are outlets for each apartment in the basement for washers/dryers. I suspect the tenant in the basement apartment may have plugged something into one of those. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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