Wegmatt dAISy Owner's Manual - page 11
In a nutshell: The farther you can see, the better.
6.3 Radio noise
The main weakness of dAISy, and probably most low-cost and SDR-based AIS receivers, is susceptibility
to radio noise. The effect of noise is reduced range and few successfully received packets.
Unfortunately, there’s not much we can do except finding a spot that’s less impacted by noise. Outdoors
is better than indoors (computers, power-supplies, wireless networks, ...). Country-side is better than
down-town (taxi radios).
dAISy has an integrated 12 MHz wide bandpass filter to reduce the impact of radio noise outside the 162
MHz target frequency. However, to keep cost and size down, the integrated filter is rather simple. A very
narrow-band antenna or an external bandpass filter can improve reception. Please report back any
results if you go down this route.