Transmitter PPM signal

[pugs]

Sitting here thinking about the models I want to build, and researching the 2.4 ghz transmitter stuff (I'm used to crystal sets yet). Thinking why not build a radio the way I want, to do what I want. I know how to use the 2.4 ghz antenna stuff and about the electronics of wiring joysticks and switches and power supplies etc. Where I'm lost is how to you convert the analog inputs of a joystick or two into the PPM signal (common method that RC radios use), and one that a standard reciever can decode??

I know a way around needing the PPM signal but it would result in a large transmitter and reciever and not work with standard servos etc. Just curious if anyone on here knows more about the PPM side of RC transmitters or has some links to something that explains it.