Your first reception

From a plugged-in radio to a decoded signal in five steps.

Before you start

You need OnAir installed (Install) and, for real signals, an SDR with an antenna. The radio guide says what each radio can receive. A TV channel needs a radio that samples fast enough: roughly one million samples per second per MHz of channel width.

No radio yet? Press Tour (Help > Guided tour). A friendly little TV walks you through OnAir on a built-in demo signal, and most modes have a built-in synthetic test signal in the radio list.

The five steps

1. Connect your radio and antenna, then start OnAir. Connected radios appear in the source list. On Windows install the WinUSB driver first (Install). The first time, a Setup wizard asks which radio you have, where you are (it picks the right TV standard and FM band), optionally your position and what you want to receive. You can run it again from Help > Setup wizard.
2. Pick what you want to receive in the mode list. The list has search and 15 groups: TV, broadcast radio, aviation, maritime, satellite and navigation, two-way radio, cellular and rail, pagers, IoT and sensors, weather and science, amateur digital, amateur voice and packet, HF utility, and general and tools. The first nine modes also have the keys 1 to 9 (Mode menu).
3. Enter a frequency, or open the Scan tab to find channels automatically. Every mode has a sensible start frequency. OnAir never limits the frequency you type: if the radio is not specified for it you get a note, not a block.
4. Press Start. When the receiver locks, the channels or results appear: click a TV or radio channel to watch or listen.
5. Improve the signal. If the picture breaks up use Auto-tune for the gain, or Optimise gain, which sweeps the radio's whole gain range, measures the mode's signal-to-noise ratio and keeps the lowest gain within 0.5 dB of the best one that does not overload the converter (Undo gain goes back). Then move the antenna while you watch the quality score. Height and a clear view toward the transmitter matter more than anything else.

What you should see

• A spectrum and waterfall of the band around your frequency.
• The status lights and numbers: locked or searching, signal-to-noise ratio, error counts, a quality score, and for TV an echo (multipath) indicator. The main window page explains each part.
• In the mode tab, the decoded result: a channel list for TV, a station name and radio text for FM, aircraft on a map for ADS-B, and so on. The mode reference says what each screen holds.

If nothing happens

• No radio in the list: check the cable and the USB driver, then press Rescan for devices.
• Spectrum but no lock: wrong frequency or standard, a weak signal or too much gain (look at the ADC level). See Troubleshooting.
• Nothing at all and you only want to explore: choose the synthetic source.

Where next

• Tutorials for common projects.
• Record IQ and open it in the Signal workbench to keep a signal and look at it later.