OnAirHF utility · Experimental
Decode HF beacons with an SDR
OnAir receives HF beacons. HF beacon propagation monitor: which NCDXF/IARU International Beacon Project beacons (18 beacons on 14.100, 18.110, 21.150, 24.930 and 28.200 MHz, 10 s slots), Australian Long Dashes and Russian single-letter beacons can be heard from here, by band, with SNR, distance and bearing, a great-circle map and 24 hour history; an editable beacon list; clicking a beacon tunes and listens.
What HF beacons is
The NCDXF/IARU International Beacon Project transmits on five HF frequencies in a fixed rotation, so you can tell at a glance which bands are open to which parts of the world.
Frequencies and where it is used
NCDXF/IARU, Long Dashes, single letters.
In OnAir the tuning shortcut is NCDXF/IARU, Long Dashes, single letters; you can enter any frequency your radio reaches.
What OnAir shows for HF beacons
HF beacon propagation monitor: which NCDXF/IARU International Beacon Project beacons (18 beacons on 14.100, 18.110, 21.150, 24.930 and 28.200 MHz, 10 s slots), Australian Long Dashes and Russian single-letter beacons can be heard from here, by band, with SNR, distance and bearing, a great-circle map and 24 hour history; an editable beacon list; clicking a beacon tunes and listens.
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
This is a shortwave mode, so the radio has to tune HF. An SDRplay, Airspy HF+ or an RTL-SDR in direct-sampling mode do that directly; with a HackRF an HF upconverter or a direct-sampling receiver is the usual route. A long wire or loop antenna matters more than the radio.
Questions about HF beacons
Can I decode HF beacons with an RTL-SDR?
An RTL-SDR can receive HF only in direct-sampling mode, which OnAir offers in its radio settings; results depend on the antenna. SDRplay and Airspy HF+ radios are better suited.
Is it legal to receive HF beacons?
Some HF utility traffic belongs to governments or the military. Receiving is legal in many countries, but rules differ. Check them where you live.
Can I try HF beacons 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.