OnAirIoT & sensors · Experimental
Decode ISM sensors with an SDR
OnAir receives ISM sensors. Everyday 433.92, 868 and 915 MHz devices: weather stations, tyre pressure sensors, remotes, energy and water meters, Z-Wave (passive; S0 and S2 stay encrypted).
What ISM sensors is
Weather stations, tyre pressure sensors, remote controls and meters transmit short packets on 433, 868 and 915 MHz that a software-defined radio can read.
Frequencies and where it is used
433.92 / 868 / 915 MHz devices (the rtl_433 idea).
In OnAir the tuning shortcut is Sensors, 433 / 868 MHz; you can enter any frequency your radio reaches.
What OnAir shows for ISM sensors
Weather stations, tyre pressure sensors, remotes and energy / water meters (wireless M-Bus header), and Z-Wave R1 / R2 / R3 (ITU-T G.9959: Home IDs, nodes, command classes; passive receive only, S0 and S2 traffic stays encrypted and is never decrypted): a device table with history, a Z-Wave view grouped by Home ID, a live log, unknown signals with their pulses.
This receiver is built from the published specification and checked end to end on simulated signals. It has had little or no testing on real transmissions yet, so reports and recordings on Discord are welcome.
Which radio you need
Any radio that tunes this range works. An RTL-SDR covers roughly 24 MHz to 1.7 GHz, and every other radio in the radio guide reaches it too. Antenna height and a clear view of the transmitter matter most.
Questions about ISM sensors
Can I decode ISM sensors with an RTL-SDR?
Usually yes for narrowband signals, as an RTL-SDR tunes roughly 24 MHz to 1.7 GHz at up to about 2.4 Msps. Wide signals such as TV channels need a faster radio, and OnAir says next to the source what the selected radio can do.
Is it legal to receive ISM sensors?
This mode is passive. It only receives, never connects, pairs or joins networks, and never decrypts payloads. Check the rules where you live.
Can I try ISM sensors in OnAir without a radio?
Yes. Most modes include a built-in synthetic test signal, so you can open the screen and try the controls before you own a radio.
Try it without a radio
OnAir includes built-in synthetic test signals for most modes, so you can open this screen, see the layout and try the controls before you own a radio. The Tour button walks you through the app.