[Technical] Using rtl_433 with Salter temperature probe

 So, you bought a Salter brand oven thermometer, FCC ID 2ATK8-BS201, and it has a nice removable remote that listens to radio chirps from the base to report the temperature. Great! It's a nice, functional product, even if the FCC ID doesn't seem to exist. (!)

If you want to use it with rtl_433 and an SDR, though, you'll find that it reuses the ThermoPro TP12 protocol under the hood.

Well, that's easy enough--except it reports two temperatures, and neither of them seem remotely correct. If you watch closely, though, you'll find that "temperature_1_C" is exactly 30 degrees C over the temperature reported on the remote.

I haven't figured out what temperature_2_C is yet, but it does seem to track with temp 1 at least a little.