Bandwidth & selectivity

Bandwidth sets how wide a slice of the spectrum the radio listens to. Wider lets through more of the audio (and more of the neighbours); narrower rejects interference at the cost of muffled sound. On a crowded shortwave band it is one of your most useful controls.

The widths available

The choices depend on the mode:

• AM: 1.0, 1.8, 2.0, 2.5, 3.0, 4.0 and 6.0 kHz
• SSB: 0.5, 1.0, 1.2, 2.2, 3.0 and 4.0 kHz
• FM: automatic

How to choose

Start wide for the best fidelity. If a station on the next channel splatters into yours, step the bandwidth down until the interference falls away. The audio gets duller, but it becomes easier to understand. For SSB voice, around 2.2 to 3.0 kHz is a good default; narrow to 1.0 to 1.2 kHz to dig a weak signal out of a pile-up. For an AM broadcaster in the clear, 4 to 6 kHz sounds best; drop to 2 to 3 kHz when the band is crowded.

In the app

Bandwidth has previous and next buttons, and the current width shows in the status panel. There is nothing to set for FM; the radio handles it.