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Driving around listening to one of my favourite radio stations, BBC 5 Live, which is broadcast on medium wave (MW), I have noticed that the reception is significantly poorer at night than during the day.Why?Chris
Actually, that raises an important point: why is this effect most pronounced with MW and not with, say, FM?Chris
AM is more susceptible than FM to degradation due to solar activity, metal structures such as bridges, etc, although FM does not propagate as well as AM, probably due to the atmosphere itself. That’s why, under a bridge, you’ll get static on AM stations but not on FM stations. At night, the Earth blocks solar interference, allowing AM to broadcast even farther than normal, which was how, while tuning through my lousy car radio in Massachusetts, I picked up a Chicago AM station! I listened to it thinking it was local until it gave the time as one hour earlier than what I knew it to be.
...so if FM suffers the same decrement to the amplitude, why doesn't the FM signal fluctuate i.e. become a bit quieter, despite the content remaining clear? Or does it?Chris
So is one of the FM bits set as amplitude i.e. loudness then? Is that how the music / audio volume is determined?