MIT Radio Society Lectures on Radio Technology Now Freely Available on YouTube
At the beginning of this year the MIT Radio Society held a series of nine lectures all about radio. The lectures cover topics like the history of radio, radio technology, signal modulation and phasor analysis, software defined radio, ionosphere, shortwave radio, propagation, radio astronomy, low frequency radio astronomy for the observation of exoplanets, principles of radar, space weather and 5G cellular comms and the future of radio. The lectures have all been uploaded to YouTube for free viewing, and can be found on their playlist.
If you're interested in learning more about radio this series of lectures is an excellent start, and lecture three specifically focuses on software defined radio.
An Introduction to Radio Experimentation, Technology, and History