There are many different varieties of modulation ... amplitude modulated signal. The demodulation process for AM where the radio frequency signal is converted into an audio frequency signal is very ...

Common digital modulation techniques include amplitude-shift keying ... In the past, unique circuits implemented modulation and demodulation. Today, most modern radios are software-defined ...

He’s broken down the modulation and demodulation circuits into their basic op-amp stages with examples of what the signal should look like on a scope after each stage. That’s the beauty here.