OnAirAmateur: digital · Experimental
Decode FT4 with an SDR
OnAir receives FT4. FT4 contest mode in 7.5 s slots, 14.080 MHz.
What FT4 is
FT4 is the contest-oriented relative of FT8, with 7.5-second slots.
Frequencies and where it is used
WSJT, 14.080 MHz.
In OnAir the tuning shortcut is WSJT, 14.080 MHz; you can enter any frequency your radio reaches.
What OnAir shows for FT4
FT4 contest mode in 7.5 s slots, 14.080 MHz.
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 FT4
Can I decode FT4 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 FT4?
Amateur radio signals are meant to be received. Receiving needs no licence in most countries; OnAir does not transmit.
Can I try FT4 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.