Do RF devices degrade over time?

[ccaru]

This might not be related to Domoticz but rather a general issue I am having with many RF devices I have installed in the past 5 years.

In general, I'm using Domoticz and an RFXCOM to control a number of switch receivers - mainly Intertechno / Trust 433 devices, and Somfy RTS blinds. Most are connected directly via an intertecho/trust wall rocker switch or standard RF remotes. I'm also using RF devices on some temp sensors.

Everything was working pretty well for at least 4 years... until recently.

Problem 1 : Out of nowhere, i got a problem with RF signals from my temperature devices not being read by the RFXCOM. I could not figure this one out and finally I resolved the issue by disabling the reading of "AC" and "Lighting 4", leaving only Fine Offset/Viking and ImaginTronix enabled - which reads my sensors. This was not a big issue - all i lost was the tracking of when devices are on/off when triggered by regular remotes or wall switches. Nevertheless the reason this suddenly started happening remains a mystery. This was not a result of any hardware changes or Domoticz update. It just decided to happen one fine morning and still persists if I try to enable AC and Lighting 4 again.

Problem 2 : Around the same time that the above happened, the majority of my remotes and wall switches (now simply working directly into the sensors) have becoming very unresponsive. Many times I need to click on the button 5-6 times for the signal to get through.

What does remain quite reliable is if I control the lights directly from Domoticz. In this case, the RFXCOM should be sending a replica of what the remote is sending ("learn" function in Domoticz, originally used with the same remotes and switches which are now unresponsive).

An exception to the above is the SOMFY RTS - the remotes remain as responsive as they always were, and a blind will always respond on the first click of the remote.

Can anybody make sense of what could be the issue?

[waltervl]

Perhaps check RFXCOM support if they see this happen at other clients?
Could be that you or a neighbor installed a device that is jamming your devices?

[ccaru]

It could be (and that's what I think is most likely the cause of the problem) is some interfering device, but I have no idea how to go about it. First, I can't go and ask all my neighbours on their devices and secondly even if I find the source of the issue, I can't ask them to stop using whatever it is that's causing the problem. Given that the issue is present even if I take out RFXCOM and Domoticz out of the picture, I'm hesitant to raise this issue with RFXCOM support.

I'd like to understand more what sort of devices could cause such interference and what are the typical symptoms. So far I wasn't able to find anything constructive.

[Kedi]

Try with an antenna with a few db gain and try different polarizations.

[manjh]

I've had a similar issue many years ago, and it took me a lot of time to figure out it was a "stuck" transmittor... it was sending out signals more or less permanently.
Can you check in the Domoticz log if there is anything weird coming in?

[Kedi]

Then the battery would have been drained soon and the problem would be solved, because it stops.

[manjh]

Then the battery would have been drained soon and the problem would be solved, because it stops.

True, but you'd be surprised how long a good battery lasts... several days.

[Dave21w]

As an electronics engineer by trade I would say battery devices no (or very unlikley) but mains powered ones is a definite yes. Cheap and cheerfull mains powered devices use a very simple method of generating the low voltage required by the electronics and these parts definitely degrade over time especialy as they are on 24 / 7.
This would probably result in complete failure until said parts are replaced rather than causing interference but it is possible, all RF recievers generally have a "local oscillator" which is very low power and is mixed with the incoming signal to generate other signals, too complicated to go into here however if this circuit is not getting its proper supply all sorts of strange things can happen and if it's near enough to the RFXCom signal jamming could occured.
My biggest issue when I used to have 433Mhz devices was that most of them are one way, either transmit or receive and so there is no listen before send and I was always missing signals because 2 devices had decided to transmit at the same time resulting in a garbled mess of data which was quite correctly ignored by the RFXCom hence I moved to zigbee and have never looked back !
If you are still having problems I would suggest you pick up a cheap SDR (software defined radio) from ebay for about £10 and set it up on a laptop, set the frequency to 433.920Mhz with AM modulation and you can listen to what is going on, you should here all your devices when they transmit and you'll here the RFXcom when it send command out, if you here constant data all the time you have something stuck in permanent TX !

Dave

[ccaru]

As an electronics engineer by trade I would say battery devices no (or very unlikley) but mains powered ones is a definite yes. Cheap and cheerfull mains powered devices use a very simple method of generating the low voltage required by the electronics and these parts definitely degrade over time especialy as they are on 24 / 7.
This would probably result in complete failure until said parts are replaced rather than causing interference but it is possible, all RF recievers generally have a "local oscillator" which is very low power and is mixed with the incoming signal to generate other signals, too complicated to go into here however if this circuit is not getting its proper supply all sorts of strange things can happen and if it's near enough to the RFXCom signal jamming could occured.
My biggest issue when I used to have 433Mhz devices was that most of them are one way, either transmit or receive and so there is no listen before send and I was always missing signals because 2 devices had decided to transmit at the same time resulting in a garbled mess of data which was quite correctly ignored by the RFXCom hence I moved to zigbee and have never looked back !
If you are still having problems I would suggest you pick up a cheap SDR (software defined radio) from ebay for about £10 and set it up on a laptop, set the frequency to 433.920Mhz with AM modulation and you can listen to what is going on, you should here all your devices when they transmit and you'll here the RFXcom when it send command out, if you here constant data all the time you have something stuck in permanent TX !

Dave

That's very helpful. Thanks. I will look for an SDR as you say. It would make sense to try to understand what's going on.

[ccaru]

Try with an antenna with a few db gain and try different polarizations.

No real control over this : The problem is directly between the remote and the receivers. As for RFXCOM, I had at some point down the line upgraded the Antenna but the main issue I have is between the devices directly.

[manjh]

I moved to zigbee and have never looked back !

Fully agree. This is why I moved to ZIgbee with my critical devices, such as smoke detectors, PIR and contact sensors.

[manjh]

pick up a cheap SDR (software defined radio) from ebay for about £10

I looked for one, but can't find one for that price...

[Dave21w]

I did say about £10, this isn't far off

https://www.ebay.co.uk/itm/126003652632

[azonneveld]

In my experience CoCo wall socket receivers do degrade over time.

In case your temperature sensors are not reading well, it is probably a weatherstation transmitter that is running low on battery.
When these devices run low on battery they start jamming the 433 mhz band, don't know why.

This is the explanation given by the dutch telecom agency.

[manjh]

I did say about £10, this isn't far off

https://www.ebay.co.uk/itm/126003652632

OK, but no delivery to the Netherlands... I'll search some more.. Perhaps Ali has it.