With the rise of 2.4 GHz, new flyers may never have to deal with the AM, FM, PPM, PCM discussion above. Of course then you have to deal with
spektrum/JR vs XPS vs Futaba 2.4 GHz as they are not compatible with each other. So we avoid Pos vs neg shift and ppm vs PPM, but we now have 3 kinds of 2.4 GHz.
Such fun!
Here is a broad overview of what is going on in the 2.4 GHz market:
http://www.rcuniverse.com/forum/m_6130963/tm.htm