Here is a YouTube video about Explaining Envelope Demodulation of AM Signals and Square Law Effects, and is part of a growing collection of videos I have found to be useful. The reason is showing how basic envelope detectors have threshold effect due to square law response and understanding science related to software defined radio.
This tutorial, "Explaining Envelope Demodulation of AM Signals and Square Law Effects" is free education you can watch, which will help you deepen your knowledge and be better prepared for licence exams, schoolwork, or operating radio equipment.