OnAirMaritime · Experimental
Decode AIS with an SDR
OnAir receives AIS. AIS ship transponders on 161.975 and 162.025 MHz.
What AIS is
AIS is the transponder system on ships: identity, position, course and speed on two VHF channels near 162 MHz.
Frequencies and where it is used
Ship transponders.
In OnAir the tuning shortcut is Ships, 162 MHz; you can enter any frequency your radio reaches.
What OnAir shows for AIS
Ships on a map.
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 AIS
Can I decode AIS 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 AIS?
Receiving ship and coast-station broadcasts is legal in many countries, with limits on using or passing on private traffic. OnAir is a receiver. Check the rules where you live.
Can I try AIS 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.