You didn't mention if you're doing Continuous or Discrete, but I used Discrete-Time Signal Processing in grad school and it's considered a pretty good book.
Alan Oppenheim's lectures at MIT are also a great source of information.
Oppenheim and Schafer is a standard text. I have a very old copy and I have always thought of this stuff as an engineering version of abstract algebra.
Here is the book we used in my EMAG course in uni. I thought it was pretty decent.
https://www.amazon.ca/Fundamentals-Applied-Electromagnetics-Fawwaz-Ulaby/dp/0133356817
Looking For: Solution Manual for Fundamentals of Applied Electromagnetics, 7th Edition, Ulaby
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Amazon link for cover: https://www.amazon.com/Fundamentals-Applied-Electromagnetics-Fawwaz-Ulaby/dp/0133356817
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Well... radio communication systems are fairly complex and it's not like an Arduino kind of deal where you could bread board things and make it work. There are many system level, modulations type, hardware, and software considerations that need to be worked out. Modern RF transceivers are designed by a group of engineers each with a different specialty. For example one designs the oscillators, one designs the amplifier, another one does the system integration, a somebody is doing the digital interface and software work. Here is a decent book on receiver architecture. Here is a more circuit design related text. You can also search for a communications systems text books for a more thorough treatment.
Now if you just want to make something work like RC toys (for the lack of a better word), there are RF TX/RX IC's readily available that have the whole system integrated with a digital interface. I suggest searching for "RF Transceivers" on Texas Instruments, Analog Devices, MAXIM, Microchip, and Cypress. They typically have a demo board that has everything you need on a board to start.
I hope this is helpful. Let me know if you have more questions. I do RF and microwave circuit design for living.
Does anyone have any experience with the text "The Electronics of Radio" by David Rutledge?
A friend recommended it to me.
I have that book and it dives into the material. If OP hasn't taken Emag, then I feel that it's going to be a rough read and that it will be difficult to fully understand the equations. It's a great reference but I don't think that he should start with it since he doesn't have an RF/EE background. I wish I had a better starter reference but I don't :(.