Daniel Estévez (https://destevez.net/ https://destevez.net/) has lots of interesting blog posts on using tools like GNU Radio and Jupiter to decode transmission

Daniel Estévez (https://destevez.net/ https://destevez.net/) has lots of interesting blog posts on using tools like GNU Radio and Jupiter to decode transmissions from various objects in space. He's recently also been looking at LTE. I would also recommend CuriousMarc who has done a lot of work with his friends on restoring some radio equipment from the Apollo missions: https://www.youtube.com/watch?v=v49ucdZcx9s&list=PL-_93BVApb58SXL-BCv4rVHL-8GuC2WGb https://www.youtube.com/watch?v=v49ucdZcx9s&list=PL-_93BVApb... There are lots of good explanations of the how and why in those videos.