Here is a YouTube video about DDS controlled phasing direct conversion receiver, and is part of a growing collection of videos I have found to be useful. The reason is a receiver tuned with a DDS quadrature oscillator which produces iq output for SDR software processing and understanding science related to software defined radio.
This tutorial, "DDS controlled phasing direct conversion receiver" 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.