Hunting down rogue high powered 433Mhz transmitter?

[djos]

It is very unlikely those responsible are even aware of it. They are not pricks. Lose that attitude unless you insist on doing things the hard way.

Yeah, I'm just grumpy after putting up with this for over 6 months and spending $200 on a new garage door control board and another $110 on a Wemo maker as a backup solution to when the door isn't working. So my wife and I can get in and out of the garage.

[djos]

Do you have a smart power meter on your house?

I think some types use a mesh network, probably 433mhz.
It could be the time of the day when they all do their data dump. It would explain why your 433 mhz devices are so completely jammed if every smart meter in the street is taking on a mesh network for 15min a day.

Yes we do, I think the Victorian ones either use 3G or WiMax tho?

[djos]

Why don't you pick up a $15 RTLSDR on ebay and try that first? It will likely show you the problem or make it easier to find. An RTLSDR makes a fine 433 MHz receiver. You could also use it to listen to FM radio, and hundreds of other things.

No need to spend a lot of money on one with all the extras. Go to YouTube and plug in "rtl2832 + R820t"  There are instructions at http://osmocom.org/projects/sdr/wiki/Rtl-sdr

Cheers, I'll definitely do this.

[Muttley Snickers]

No problem here and I hope you can locate the issue, I was serious about having to head over to a plant in Canterbury Road over the next few days though and good start with these intermittent occurrences is to start a log file or list by recording the time, date and duration if possible if you intend to ferret it out yourself, these can be intriguing at times so you might need to put your Miss Marple hat on and Communications Systems Interference or CSI Kilsyth as we like to call it could be quite a story to tell in the future.

 

[djos]

No problem here and I hope you can locate the issue, I was serious about having to head over to a plant in Canterbury Road over the next few days though and good start with these intermittent occurrences is to start a log file or list by recording the time, date and duration if possible if you intend to ferret it out yourself, these can be intriguing at times so you might need to put your Miss Marple hat on and Communications Systems Interference or CSI Kilsyth as we like to call it could be quite a story to tell in the future.

 

Cheers, I enjoy problem solving but needed some help on the hardware side, thanks to all for the help, it's much appreciated.

[David_AVD]

Is there a particular model of RTLSDR that's better, but still on the cheaper side?  There are quite a few on eBay to choose from.

I was thinking of getting one, but not fond of the old "PAL" antenna connector.  SMA would suit the 433MHz leads and antennas I already have.

[cdev]

The rtl_power command line program that comes with the drivers from osmocom can be scripted to scan any arbitrary frequency band and write its output to a csv file which you can then visualize in the time dimension.  This can be very useful for clues as to when the transmissions are occurring (because you could never monitor the whole frequency spectrum by hand, yourself.)

Also, if you look around, the US government (and I am sure some others do too) has a number of publications written for scientists and the military on finding the sources of RFI. Also, Youtube user SM5BSZ has several videos on the self-construction and use of small electrical and magnetic field probes to locate EMI. He's very knowledgeable and these videos contain a wealth of information. He is the author of a SDR program which can be used with the dongles. Another, newer program which many people use is CubicSDR.

[daveshah]

Is there a particular model of RTLSDR that's better, but still on the cheaper side?  There are quite a few on eBay to choose from.

I was thinking of getting one, but not fond of the old "PAL" antenna connector.  SMA would suit the 433MHz leads and antennas I already have.

I don't think there are massive performance differences between any of the cheap ones with a R820T. None that I know of have SMA connectors but there are some cheap MCX (which is common on them) to SMA adapters on eBay.

[cdev]

I have no personal experience with it but there is a blog the "RTLSDR blog" that sells a significantly upgraded dongle for around $25 (from memory so may be wrong) which has an SMA and a 1ppm TCXO as well as a metal case. Also, I think it may have a jumper or some way to provide low voltage DC on the antenna wire which is very useful if you want to use an antenna-mounted LNA. (a built in ghetto style bias-tee)   

Thats probably the one to get if you want to spend a bit more.

[cdev]

Its a real PITA to replace a Beiling Lee/PAL connector with an SMA with just a soldering iron but easy with a hot air gun/pencil if you have one.

[vk6zgo]

You might need to know who your RF neighbors are...

http://www.wia.org.au/members/bandplans/data/documents/Australian%20Band%20Plan%2070cm%20150729.pdf

Your in a shared band, with two services having a higher priority then you,

One is mil RADAR...

Steve

As Steve points out,you are in a shared band.
To make matters worse,you are "at the bottom of the food chain",& can have no expectation of immunity  from interference.

Amateur Radio Operators,although the "Secondary Service" on this band,are quite within their rights to use 400w PEP,& various modes.
The Primary Services of Radiolocation,& Point to Point Services,although rarely seen,may use considerably more power.

Low Interference Potential Devices (LIPDS),such as your gadgets are allowed on 433MHz because they supposedly are unlikely to cause interference to the Primary & Secondary Services.(Google for LIPDs)
Unfortunately,due to their proliferation,they do cause interference,both to other services & between themselves.

The receivers used in LIPDs aren't very good,either,so they may receive strong signals from adjacent bands.(military,etc,just below 430MHz)
We had a proper allocation for remotes,etc at 315MHz,but the few remaining EEs in ACMA got "rolled" by the "suits",so importers could bring in cheap 433MHz crap.

[djos]

Has someone got a robot lawnmower? I have read they can cause interference as a result of the loop of wire used to set the boundary. They might be random. People using stuff wouldn't be random generally because people have habits.
How can you be sure it isn't something in your home maybe sending RFI over the power wires? Maybe unplug every non essential thing and then everything left when it next happens.

Did you buy something new about 6 months ago?

I doubt it, I'd notice that!

Nothing using 433 Mhz, no.

[Jay1011]

Also consider LED bulbs, those in your own house as well as perhaps ones your neighbors may have installed in nearby locations.

The cheap LED bulbs -- as well as some not-so-cheap ones -- are well-known for spewing all over the spectrum and interfering with garage door remotes and the like.  I had that experience myself, actually.  LED bulb from a company called HyperIkon (US brand name) rendered my garage door opener completely nonfunctional when the bulb was on.  When the bulb was off, all worked fine.  I switched to a Philips brand bulb and no more problems bulb on or off.

[djos]

Also consider LED bulbs, those in your own house as well as perhaps ones your neighbors may have installed in nearby locations.

The cheap LED bulbs -- as well as some not-so-cheap ones -- are well-known for spewing all over the spectrum and interfering with garage door remotes and the like.  I had that experience myself, actually.  LED bulb from a company called HyperIkon (US brand name) rendered my garage door opener completely nonfunctional when the bulb was on.  When the bulb was off, all worked fine.  I switched to a Philips brand bulb and no more problems bulb on or off.

I've come home to a powered down house many times to find my Garage door wont respond so Im fairly confident my LED's aren't the cause. Like you Im running Philips LED's in the entire house without issues.

[Muttley Snickers]

For the garage door reliability you can always connect a completely different remote control and receiver card operating on another frequency altogether should the current issue not be identified, you simply wire the momentary dry contacts from the new receiver to the terminal input on the door motor controller where a fixed button would normally be wired in. Ideally this should be powered from a separate backed up supply but your door wont open anyway if the power is out so it's optional really. This won't help with the energy monitoring system though as you well know but at least it's a start.

[djos]

For the garage door reliability you can always connect a completely different remote control and receiver card operating on another frequency altogether should the current issue not be identified, you simply wire the momentary dry contacts from the new receiver to the terminal input on the door motor controller where a fixed button would normally be wired in. Ideally this should be powered from a separate backed up supply but your door wont open anyway if the power is out so it's optional really. This won't help with the energy monitoring system though as you well know but at least it's a start.

We've had a new board operating on a slightly different frequency Installed that required new remotes. It improved but we still get periods where you can stand under the unit and press the remote and it might as well be powered off ... nothing happens.

As mentioned in an earlier post, I grabbed a Wemo Maker from Bunnings and wired it up to the "wired door button" terminals in momentary mode. Plus I added a normally open magnetic security sensor so we can use our phones to see if the door is closed/open and open/close it if the remotes are blocked. To make it even easier for the Wife, I created an IFTTT recipe and added the Do widget her her lock screen (and mine) so she can easily and quickly operate the door if the remotes are blocked.

The energy monitoring system is not affected nearly as much or as badly as it operates on a slightly different frequency to the Garage - Im not bothered if I lose 10mins here or there every few days, it's a minor nuisance compared to the garage door not allowing ingress or egress.

[djos]

If only you'd known of those before shelling out for a new control board.

I've been having a private chat to Muttley (thanks mate) and he's suggested there could be an intermittent fault with the new control board based on the fact that when it stops working it's as if it is dead, even standing under it with the remote when it's playing up doesnt produce a result. Both previous boards still worked when standing under them, just not from2 metres away.

As a result I'll get Steel-line back out to replace the board in the new year. TBH they've been pretty darn good to deal with so far and their tech is a top bloke to chat to.

Does the loss of data show the times and duration of the interference? This is  nice little mystery. For someone not aggravated by the inconvenience.

Yes I log all the failures to capture data over 15 minutes in duration to email which I can then cross reference with the missing data in PVOutput. see attached:

[djos]

Your screenshot doesn't appear to include Dec 20th and I noticed 8 data points missing from that day. Including 3:10PM 3:15 3:25 and 3:40

No obvious pattern in the three days I looked at. It seems data is missing from times throughout the day and night. I was looking to see if it was heat related but the weather hasn't been particularly hot lately.

Is the power supply separate from the control boards being replaced? Not sure how that might explain the energy monitor going awol but one might relate to the other if interference is in the mains wire. Grasping at straws I know.

You know what I would do? I would disconnect the garage door opener for a time just to see if the energy monitor stops playing up. At least it will provide a log to assist verification. Even one day may prove something.

December 20th is the top most item. You're quite correct, there are more missing data points but I'm only logging the 15 minute plus losses or my mailbox would be smashed even harder than it already is. Kudos for looking up my data on PVO.

The transmitter uses 2 D cells which last four about 4 years, these ones are about 9 months old. It uses a standard CT clamp on the mains active wire going into the switch board. Simple but accurate enough for my needs.

The receiver is on a UPS along with my server. Even if the receiver loses connection to the server (good old fashioned reliable RS232), it stores several days worth of data which the service on the server will extract next time it connects.

I've done the isolation tests, they aren't inferring with each other.

Regarding the garage door, it's a single board solution but the power supply is separate, I thought that wasn't the case but I just popped the back off to confirm.

[LaserSteve]

You should have seen capture effect, or near field saturation when standing right under the door receiver. Unless you have a Tetra site or a radar right on top of you, or the very unlikely ATV transmitter, my bet is your interference source is within feet of you.

Any big towers within a kilometer or two?

Steve

[Buriedcode]

After designing a 433MHz 'basic' network for home automation, I looked at the spectrum and there were indeed *many* transmissions flying about on this band.  However, things like wireless doorbells, car alarms, weather stations etc.. are all rather low duty - from 2-3 bursts a day, to every coupe of minutes, certainly not something that would kill a link for hours at a time unless your kit juts so happened to transmit at exactly the same time as the interference (so unlikely, not really worth bothering with).

So it looks like its either:
 - a continuous interference - not necessarily an active 433Mhz transmission, could also be EMI generated from something else,
 - the antennas of your systems are poorly placed.. or.. just-so-happen to be in dead spots.
 - your equipment is faulty.

After reading the thread is seems like that the 3rd option is unlikely. And I'm sure you would have eliminated the second by moving things about (especially in the case of a garage door opener, side step and chances are if it was multipath, it would work fine).

So whilst I've just come back to what you suggested in your first post, best to eliminate other things first!

As suggested, the only real way is to 'see' the band with an SDR.  This will also be able to show if its a bonafide 433Mhz transmission, or random noise something is kicking out across this band.
It would have to be a particularly powerful signal to interfere for long periods of time, most likely that is because the source is close to you.

[macboy]

Also consider LED bulbs, those in your own house as well as perhaps ones your neighbors may have installed in nearby locations.

The cheap LED bulbs -- as well as some not-so-cheap ones -- are well-known for spewing all over the spectrum and interfering with garage door remotes and the like.  I had that experience myself, actually.  LED bulb from a company called HyperIkon (US brand name) rendered my garage door opener completely nonfunctional when the bulb was on.  When the bulb was off, all worked fine.  I switched to a Philips brand bulb and no more problems bulb on or off.

I had an issue with LED bulbs and my opener. The bulbs cause no issues in the ceiling fixtures of the garage (5 feet away from the opener), but if I install one in the opener itself, then it will not work at all when that light is on. Not even from 1 foot away.

[djos]

I had an issue with LED bulbs and my opener. The bulbs cause no issues in the ceiling fixtures of the garage (5 feet away from the opener), but if I install one in the opener itself, then it will not work at all when that light is on. Not even from 1 foot away.

Interesting find, I have a Philips LED globe in mine, I might switch it for an incandescent globe just to see if it makes any difference. (In 2 weeks when I get home from holidays)

[djos]

You should have seen capture effect, or near field saturation when standing right under the door receiver. Unless you have a Tetra site or a radar right on top of you, or the very unlikely ATV transmitter, my bet is your interference source is within feet of you.

Any big towers within a kilometer or two?

Steve

About 10 kms away we have a stack of transmitters for FM radio, TV etc on top of the Yarra ranges near us but no military bases anywhere near us that I'm aware of.

From your comments, and others, I'm beginning to think the new board has an intermittent fault.

[djos]

Got a "dear Joe public" email from ACMA today advising me to try everything I'd already tried - clearly it was a form letter.

No big deal, I have a few avenues to try when I get home from holidays in 2 weeks.

[cdev]

I would be happy that the failure mode was simply not being able to open the door without getting out of one's car, and not have the garage door open!

Can (OP) turn off the RF receiver part of your garage door opener and use a key switch mounted next to the door as a back up?

It seems that so many devices use the 433 MHz band now that many now have collisions.