Mode Spectrum analyser

Spectrum analyser: fast wide sweeps with markers and band labels.

Group	General & tools
Default frequency	100 MHz
Default sample rate	20 Msps
In the mode list	Sweep, 1 - 6000 MHz

Step-by-step: Tutorial-Spectrum-analyser

What Spectrum analyser is

The spectrum analyser sweeps a wide range quickly, with peak hold, averaging, markers and a band overlay.

Frequencies and settings

Wide sweeps, 1 - 6000 MHz in about a second with a HackRF (its native sweep), stepped retuning on other radios.

Setting	Value
Start frequency	100 MHz
Tuning range of the mode table	1 to 6000 MHz
Sample rate asked	20 Msps
Lowest working rate	1 Msps
Channel width	15 MHz

OnAir takes any frequency you type; the numbers above are the mode's starting point and the range its table describes. In the app the shortcut label is Sweep, 1 - 6000 MHz.

What OnAir shows

Live, peak-hold and averaged traces, persistence, waterfall, markers, EU band overlay, spur removal, CSV export with every bin at the chosen RBW (streamed to the file; the expected size is shown), automatic CSV saving every N seconds into a folder (timestamped specan_YYYYMMDD_HHMMSS.csv, optional limit on files kept).

Tips and caveats

• This is a tool for looking at the spectrum and recordings, not a decoder of one standard.
• Which radio: Usually yes for narrowband signals: an RTL-SDR tunes roughly 24 MHz to 1.7 GHz at up to about 2.4 Msps. Wide signals such as TV channels need a faster radio, and OnAir says next to the source what the selected radio can do.
• Try it without a radio: most modes include a built-in synthetic test signal, so you can open the screen and try the controls first.
• Receiving and the law: These tools only look at the spectrum and listen. Receiving is legal in most countries, but laws differ on what you may use the content for. See Legal.

Related pages

• All modes, General & tools
• Supported radios, Troubleshooting, FAQ
• More in General & tools: Signal workbench, General receiver, Spectrum explorer