Here is a YouTube video about Open Source Adaptive Digital Predistortion Technology by Borisav Jovanovic, and is part of a growing collection of videos I have found to be useful. The reason is creating signals of far greater purity and understanding science related to software defined radio.
This tutorial, "Open Source Adaptive Digital Predistortion Technology by Borisav Jovanovic" 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.