[AllyCat]

Many devices that are not RFID devices are sold which use 433.92MHz for unlicensed transmitters, including commercially sold weather stations that have been sold for decades in the US and are still sold to this very day.

Everything from remote tire pressure sensors to doorbells, weather stations, gate openers, wireless light switches, driveway alert systems, LITERALLY everything under the sun operate completely legally and unlicensed there.

"Unlicensed" simply means that it is not necessary to apply (and maybe pay) for a "Broadcasting" License to operate the specified equipment, it does NOT mean that you can transmit whatever you like.  The equipment must still comply with ALL the relevant broadcasting regulations for the band.

To me, a key phrase is "are Sold"; the equipment will (should) have been designed to comply with all the regulations and may have been submitted to a professional "Test House" for confirmation of its compliance with the complex regulations (you cannot simply cut-and-paste the bits that you like).

Also, that list above is certainly not "Everything", ALL those examples are designed to broadcast for very brief periods of time.  The regulations typically specify a "Duty Cycle" of 1%, sometimes 0.1% or 10% depending on the power level (ERP), for example.  Unfortunately the "averaging" period is not normally specified, so it might be minutes, hours or days, but it is clear that a baby alarm or wireless headphones, etc. would not comply (there is another band allocated for them).  Often the regulations will specify "data" or "voice" and exclude the other.

Actually, even "pushbutton" type devices like door bells/openers may further restrict their transmission time by using "start" and "stop" commands rather than broadcasting continuously whilst a button is pushed.  I've not studied the transmitting duty cycle of the Weatherduino software, but the overall repetition rate of 3 seconds (or less) is very considerably shorter than most/all commercial sensors, which typically transmit for less than  a few hundred ms approximately every minute or more.

Cheers,  Alan.