I don’t think I was ever taught this but thinking about it it seems like suck a futuristic concept and I wanna know how they both work. Like, how do these things send invisible, intangible signals?
In: 65
AM audio broadcast is probably the easiest to explain since it’s not digital.
Let’s first start with audio. Audio is a pressure wave traveling through air. A pure wave is just a simple whistle or hum tone depending on the frequency. You can add frequencies together, if you do it randomly you will get white noise. If you do it in a very very specific way you will get spoken words or music.
Now we need to turn that pressure frequency somehow into electrical current. For that we can use the convenient tool called the microphone which can just do that 1 to 1.
If you now want to transmit it, you have to add just one more frequency which is called the carrier. Let’s pick on from the visible light spectrum for example green. AM stands for amplitude modulation and just means we make our green light brighter or dimmer. If we add our signal to the green light it gets brighter and dimmer exactly like our audio signal.
Everyone who sees our flickering light just needs to know that we added the green frequency to our signal. If they remove the green part they will have exactly the original audio signal and just have to feed it through some speakers to turn it back into pressure waves.
In reality the carrier frequency is much lower than visible light and there are many different and more efficient ways to add information to the carrier.
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