Analog Demodulation Measurements
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Basics of AM, FM, and PM Modulation Types
Why modulate an analog signal in the first place? If you need to transmit an audio signal over a great distance, you may find it challenging to transmit that data as is. Audio signals do not have the correct properties to reach a receiver that is far away or to penetrate obstacles that may be in the way. You could blast the volume, but you will only succeed in annoying your neighbors.