The OnAir main window explained

OnAir has several layouts (View menu: Sidebar, Scope, Tiles, Faceplate, Scope: Cinema, Scope: Meters, Scope: Dock and Panel), plus a classic interface. They all use the same parts, so this page names the parts rather than the pixels. The layout adapts to small windows and to 125 % and 150 % display scaling.

Menus#

The top bar#

• Start / Stop and the frequency field. The mouse wheel or a trackpad steps the frequency in the classic frequency field; the arrows repeat when held.
• The radio (source) choice and the sample rate.
• Clear all (0.2.6) wipes every decoded list after a confirmation. Results stay until you press Clear, across mode switches and restarts.
• The version button at the top right shows the update state and holds the update settings. Support opens Ko-fi.

Spectrum and waterfall#

• The spectrum shows the power of every frequency the radio sees; the waterfall below shows it over time, newest at the top.
• Hover a slider and scroll to change it by one step (Shift = fine, Ctrl = coarse); the window does not scroll meanwhile.
• The dB range fields work at any time; Ctrl+Up / Down moves the range, Ctrl+Shift+Up / Down widens or narrows it and Ctrl+Home resets it.
• Colour maps, pause and scroll-back, averaging, max hold, peak markers and dBm are in the display options (0.2.6); a Cividis colour map helps with red-green colour blindness.
• Click a signal on the spectrum and the signal identifier gives its width, rate, modulation and a suggested mode.
• A decoder counter sits at the top right of the spectrum (0.2.6).

Panels#

In the Sidebar layout the panels are folded sections; other layouts show them as tiles or modules:

• Source: choose the radio, press Rescan for devices, Record IQ (see Settings and files), add a network radio or a Hamlib rig.
• Gain: Auto-tune, Optimise gain and the radio's gain stages (for a HackRF: LNA, VGA and the Amp switch). Radio settings offers what the radio has: frequency correction (ppm), notch filters, gain modes, direct sampling for HF, up-converters and LNBs.
• Tuner: the frequency, the sample rate and the mode's own options.
• Mode: the mode list with a search box.
• Display: spectrum range, colour map and waterfall options.
• Decoder: shown for modes that have decoder options.
• Tools (folded, 0.2.6): passes, images, feeds, map, scanner, light theme, accent colour and text size, so they are not only in the View menu.
• Log: what the receiver is doing, with warnings in plain words.

The tabs#

The tab bar changes with the mode. A TV mode has:

Radio modes have a Radio tab (FM) or Radio, Ensemble, Map, Analyzer, Journaline and FIC tabs (DAB). Every other mode has its own tab named after the mode, with sub-views such as Map, Table and Messages; each mode page lists them.

Status and results#

• The status bar shows lock state, SNR, quality, whether samples are being dropped, the process CPU load and, for a network radio, the samples lost.
• Save results... writes CSV or JSON, an ADIF logbook for the amateur modes, and KML or GPX for anything with positions.
• Two modes at once from the same capture: add a second mode and its tab appears as Second: <mode>. Several receivers at once: see Use two receivers.