Opentherm Gateway disturbing 433 Mhz signal reception?

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Opentherm Gateway disturbing 433 Mhz signal reception?

Postby gijss » Sat Oct 10, 2015 7:54 pm

Hello,

I have been testing the OTGW for the past weeks and I have noticed it seems to jam my reception of 433 Mhz signals. I have both the OTGW (via USB) and 433 (via arduino nano/USB/pimatic) on the same Raspberry Pi 2. They are physically about 2 m separated. What I have noticed is that after the OTGW has been plugged in for some time (this can be hours or days) I do not receive the signals of my outside weather station anymore. I have subsequentely removed the OTGW from the USB, without success, but when I remove it from the power my reception is good again.

Is this at all possible, or am I drawing conclusions which are not sound?
I very much appreciate your input.

Gijs
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Re: Opentherm Gateway disturbing 433 Mhz signal reception?

Postby vincenttor » Sun Oct 11, 2015 8:03 am

Try to make a simple shield for testing.
Make it from aluminum foil for example then place around the other.
See of this does something, otherwise you can try to use ferrite cores and put the power wires around /through the core a couple of times .

Thee things may help you
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Re: Opentherm Gateway disturbing 433 Mhz signal reception?

Postby hvxl » Tue Oct 13, 2015 4:25 pm

I can't image how that could be the case. The highest frequency used in the OTGW is the internal clock of the PIC, which runs at 4MHz. That's nowhere near the frequency it is supposedly jamming. What's more, that 4MHz signal never leaves the PIC. The highest frequency you can actually get your hands at is the opentherm signal, which is only 2kHz.
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Re: Opentherm Gateway disturbing 433 Mhz signal reception?

Postby vincenttor » Tue Oct 13, 2015 7:12 pm

Maybe a faulty psu, i have found many strange things with a radio by walking in the house that interfered on many bands.
Placing it into a shielded box and use ferrite would help in some cases, so like i said above here, try to see if it works :wink:
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Re: Opentherm Gateway disturbing 433 Mhz signal reception?

Postby gijss » Wed Oct 14, 2015 9:21 pm

Thanks for your answers. I agree it sounds unlikely but testing is very very convincing, as soon as I unplug the power from the OTGW signal reception increased dramatically. And this is without the USB connected.

Vincent, thanks for your suggestions.
I have tried with Aluminium wrapped around the box, but it seems the USB wire itself also acts as an antenna somehow, disturbing the signal. If everything is wrapped in Aluminium the signal improves but is still not 100%.
Is there anything I could have lying around that I could use as a ferrite core? I have never done this before, any tips?

Thanks very much for your help,

Gijs
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Re: Opentherm Gateway disturbing 433 Mhz signal reception?

Postby vincenttor » Thu Oct 15, 2015 5:28 pm

On the older computer monitors they have normally sometimes the removable ferrite cores.
The thing is, when you use ferrite.
Put the wire 1 time trough the core works, but the best is when you put the wire a couple of times trough the core.
Image

But now when i think about it, ferrite is not going to do anything because the wire works as an antenna or something similar.
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Re: Opentherm Gateway disturbing 433 Mhz signal reception?

Postby gijss » Sat Oct 17, 2015 9:52 pm

Well, thanks for the suggestion anyway.
I decided to move the OTGW somewhere else, but now I am having another problem. The OTGW is not communicating properly with the boiler. I am getting continuously Error 03. I tried changing the reference voltage, but it does not seem to matter.
The wire is significantly longer and I have had to make some connections, but it is working fine when I connect it directly to the thermostat, so I don't think it should be an issue.

Any suggestions much appreciated...

Gijs
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Re: Opentherm Gateway disturbing 433 Mhz signal reception?

Postby vincenttor » Sat Oct 17, 2015 11:20 pm

how is the boiler connected to the gateway ?
is there a shielded utp wire between it or something similar ?
Because this can cause trouble also, well not sure if it does with this but its something you can look into.
With 1-wire system and using some length they say not to use a shielded wire because of the shielding that causes interference.\
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Re: Opentherm Gateway disturbing 433 Mhz signal reception?

Postby gijss » Sun Oct 18, 2015 7:28 am

vincenttor wrote:how is the boiler connected to the gateway ?
is there a shielded utp wire between it or something similar ?
Because this can cause trouble also, well not sure if it does with this but its something you can look into.
With 1-wire system and using some length they say not to use a shielded wire because of the shielding that causes interference.\


And there I was thinking shielded wire is always better. Anyway, the cable I am using is not shielded (https://www.netwerkwinkel.com/Netwerk-m ... _2588.html). There is also going LAN traffic through the same cable though, which might cause interference. But like I said, the Isense thermostat has no problem working perfectly on the same wire.
Because of the Error 03 (which I have experienced also in my previous setup, but I could solve it by changing the reference voltage) I have checked the R5 and R6 resistor, and although the R6 resistor measures 3KOhm rather than 4.7, when I take it out it is 4.7kOhm so it is probably due to the rest of the circuit that I measure it at 3kOhm.

Another thing which I now realize might actually be the cause of all my problems, is that I made a mistake soldering the voltage regulator TO220 on the board, I did it the wrong way. This caused the PIC to fry. I am using a new PIC and it is behaving OK as far as I can see, but I cannot exclude that some other components have also been affected, possibly causing both of these issues.
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Re: Opentherm Gateway disturbing 433 Mhz signal reception?

Postby hvxl » Sun Oct 18, 2015 11:45 am

Are you getting the errors from the thermostat or the boiler side? The boiler communicates using current, which should be quite immune from interference. Is the communication working with the gateway in monitor mode?
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Re: Opentherm Gateway disturbing 433 Mhz signal reception?

Postby gijss » Wed Oct 28, 2015 7:43 pm

Sorry for the long delay, but I wanted to be sure it is working now.
I have rechecked all the connections and now the gateway is running as I think it should. No more Error 03's or connection issues.

Thanks again for your help,

Gijs
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