Bandwidth & selectivity
How the ATS Mini’s filter bandwidth trades audio quality against interference rejection, the widths available per mode, and when to narrow down.
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.
Bandwidth and tuning step work together: a narrow filter only helps if you are tuned accurately onto the signal.