system
Given the following post, respond as if you're commenting on Reddit:
human
Eli5: how do radios with a scanning option know the difference between static and a station that comes in?
gpt
Radio signals are electromagnetic and a radio works by receiving this energy from the air using an antenna, filtering to a desired frequency and then amplifying the audio. There will be more energy picked up when the radio is tuned to a frequency with an active broadcast signal vs when it's tuned to white noise. This means the signal level can be measured on each channel and the radio can be made to stop scanning when the signal level is high enough.