OnAir FAQ: radios, modes, encryption, legality, voice codecs

General#

What is OnAir?#

A free, open-source application for macOS, Windows and Linux that turns a software-defined radio (SDR) into a receiver and decoder: digital TV (DVB-T2, DVB-T, ATSC, ISDB-T, DTMB, DVB-S/S2, DVB-C), radio (DAB+, DRM, HD Radio, FM with RDS), aircraft and ships, satellites, two-way radio, pagers, amateur digital modes, IoT and much more. It shows the spectrum, waterfall and constellations so you can see what the receiver is doing. The mode list has every entry.

Is it free?#

Yes: GPL-3.0-or-later, no account and no subscription. If it is useful you can support it on Ko-fi.

Which radios work?#

The HackRF One and Pro natively; BladeRF, LimeSDR, USRP, PlutoSDR, Airspy, SDRplay, RTL-SDR, Airspy HF+, Fobos and RX888 directly; network radios; anything with a SoapySDR module. See Supported radios.

Do I need a radio to try it?#

No. Press Tour, or choose the synthetic source: most modes include a built-in test signal. You can also open recordings from the sample library.

Which operating systems?#

macOS 15 or later (Apple silicon and Intel), Windows 10 / 11 64-bit, Linux x86-64 and arm64. There is no Android app yet: see Android.

Why is my radio not found on Windows?#

Install the WinUSB driver with Zadig. See Troubleshooting.

Signals and law#

Can OnAir decrypt encrypted channels or calls?#

No. Encrypted TV services cannot be decoded, and encrypted radio calls (DMR, P25, TETRA and others) are only reported as encrypted. Nothing is decrypted.

Is it legal?#

Receiving broadcasts is legal in most places, but laws differ, especially for private two-way radio, pagers and some aviation or maritime traffic. OnAir is built to receive; what you may do is up to you. See Legal.

Which modes have been tested on real signals?#

Every mode page says what the mode was checked with. Where a mode has only been checked on generated signals, the page says exactly that, and recordings of real signals are welcome: upload them to the sample library or send them on Discord.

Why no sound on DMR, P25 or D-STAR?#

Those use patented voice codecs that OnAir does not ship; you provide the library. See Voice codecs.

Does OnAir transmit?#

The released versions receive. The 0.2.6 development build adds a separate transmit view for licensed users; see the notes on the Transmit page.

Using it#

How do I improve a weak signal?#

Antenna height and a clear view toward the transmitter matter more than anything else. Use Auto-tune or Optimise gain and watch the quality score and the echo detector.

Can I watch TV on another device?#

Yes: the built-in network tuner streams channels to VLC, phones, Plex or Jellyfin, as a plain stream or HLS. On a Mac you can cast to AirPlay. See the DVB-T2 tutorial.

Can I use two radios at once?#

Yes, up to four receivers: Use two receivers.

Does OnAir work with an RTL-SDR for TV?#

No: an RTL-SDR is too slow for TV channels. It works for DAB, FM and narrow modes.

What languages does it speak?#

English, German, French, Spanish, Chinese and Lithuanian, with Portuguese (Brazil) and Hungarian added in 0.2.6 (View > Language).

Is there a command line or an API?#

Yes: onair-cli and dect2scan and a remote-control HTTP / WebSocket API that is off by default.

Privacy and updates#

What does OnAir send over the internet?#

Almost nothing by default: an update check to GitHub. The map upload, PSK Reporter and similar are opt-in. See Privacy.

Can I turn off the update check?#

Yes: the version button at the top right has the setting, as well as automatic install and pre-releases.

Helping#

How can I help?#

Send recordings (especially for modes with little real-world testing), bug reports with an IQ recording, and pull requests; or tip on Ko-fi. See Contributing.