OnAirAmateur: digital · Experimental
Decode JS8Call with an SDR
OnAir receives JS8Call. JS8Call keyboard messaging (8-FSK, normal / fast / turbo slots): heartbeats, directed messages, relays, 14.078 MHz.
What JS8Call is
JS8Call is a keyboard messaging mode built on FT8 modulation, with directed messages, relays and heartbeats.
Frequencies and where it is used
Weak-signal keyboard messaging on HF (normal, fast, turbo).
In OnAir the tuning shortcut is Messaging, 14.078 MHz; you can enter any frequency your radio reaches.
What OnAir shows for JS8Call
Every frame in the passband, messages put together from their frames, heartbeats and CQs, relays, stations and their grids 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
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 JS8Call
Can I decode JS8Call 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 JS8Call?
Amateur radio signals are meant to be received. Receiving needs no licence in most countries; OnAir does not transmit.
Can I try JS8Call 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.