OnAirAviation · Experimental
Decode ILS with an SDR
OnAir receives ILS. ILS approach guidance: localizer 108.10 - 111.95 MHz, glide slope 329 - 335 MHz, marker beacons on 75 MHz.
What ILS is
The Instrument Landing System guides aircraft down to the runway with a localizer, a glide slope and marker beacons.
Frequencies and where it is used
Approach guidance, 75 / 108 - 112 / 329 - 335 MHz.
In OnAir the tuning shortcut is Localizer and glide slope; you can enter any frequency your radio reaches.
What OnAir shows for ILS
Localizer and glide slope needles (DDM), marker beacons, identification.
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 ILS
Can I decode ILS 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 ILS?
Receiving aircraft broadcasts is legal in many countries, but some restrict listening to or using what you hear. OnAir is a receiver. Check the rules where you live.
Can I try ILS 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.