Thanks Bruce, interesting.
I don't know enough about the signal theory to comment on the viability of using this for high-performance aerial vehicles.
There are two Bluetooth-based transmitters specifically for model ships, trucks and machinery which are "100% digital".
Their latency is too high for planes, though - but that is probably more an effect of their specialisation?
Anyway, I am currently using a Corona module attached to an Arduino microcontroller to build my own highly specialised and highly flexible transmitter. I suppose that a radio where the user has to actually code the firmware themselves would not appeal to many, but I find the possibilities fascinating - it goes way beyond what the replacement firmwares offer.
I'm using the Corona module(s) because I am just starting out with µCs and generating a PPM pulse to go into the module is much easier than doing this from scratch. But who knows, I might attempt to do it in the future (at least for my slow-moving machinery).
Cheers
Jens