868MHz thermostat

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Joined: Sat Jan 05, 2019 6:13 pm

868MHz thermostat

Post by goosst » Sat Jan 05, 2019 6:40 pm

Dear forum

This is my first experience with software defined radio.
I'm trying to decode the messages my thermostat (calormatic 370f) is broadcasting.
Since the calormatic 340 seem to be supported by rtl_433 and rflink I was hoping mine should be close enough ... .
  • Hardware I'm using: RTL-SDR Blog R820T2 RTL2832U 1PPM TCXO SMA Software Defined Radio with Dipole Antenna K
  • software I've tried to use:
    • rtl_433 (on ubuntu 18.10): when I let it listen to the 868.2MHz band (using: sudo rtl_433 -f 868.2M), nothing gets detected. If I let it listen to the 433 MHz band and I push a transmitter to turn on a light, it gets correctly detected. So hardware wise something is at least working.
    • gqrx, added some screenshots below, I don't get any clear high and low pulses that should represent a clear sequence. Which is the main issue I'm struggling with.
    • sdrsharp on windows following the quick start guide, seems to provide similar results as gqrx
    • I have tried two antenna's, the dipole antenna that came with the kit and another single pole antenna
As you can see pulses at 868.2MHz get detected when playing with the thermostat.

But I'm only able to get quite junky raw files out of it (screenshot below isn't matching the screenshot from grqx) which don't allow me (or other software) to decode anything.

Would anyone have any advice how to debug further?
  • Am I missing obvious settings when using gqrx / sdrsharp when trying to listen to the 868MHz band?
  • Anything hardware related I could investigate?
Thanks in advance!
audacity2.png (34.26 KiB) Viewed 3945 times
audacity.png (16.84 KiB) Viewed 3945 times
gqrx.png (278.11 KiB) Viewed 3945 times

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