eli5: On old radios, how does turning the dial tune into a different station? what is happening inside the radio to achieve this?
In: 70
I deal with radio frequency at work and was trying to understand a similar topic so I shall have a go – in part to get clarity on my own knowledge.
Old radios that dealt in AM sent and received signals at a set frequency but adjusted the strength (amplitude) of the signal when sending data – look at Artic Monkeys AM album cover.
FM radios keep the strength the same but alter the frequency of the signal to send data.
Signals are sent within a band width of 20, 40, 80 and 160 MHz
When you tune your radio to 90.5 FM, you are turning it to the frequency the radio station is sending out its signals – assuming it’s on a 20 MHz bandwidth, your radio is listening to all signals from 80.5 – 100.5 FM
So if there’s another channel broadcasting at say 70.5, if you turn your radio to 80.5 you end up hearing half of one station and half of another
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