Thanks Engines, I think I can safely say we all appreciate your continuing inputs to this discussion.
From your description I would imagine ## some low powered microwave link ##
perhaps ? laser
atmospherics could hinder even more unless power was ramped right up....
Anyway, I'm quite into SAT TV, No not ***, I have a steerable dish [from 50 ish east to 40 west] and I once calculated, in a moment of total nerd-ism I admit, the distance [at the sat end] moving my dish 0.1 degree, it worked out at about 135 miles give or take [quite] a bit depending on sat elevation as from my location.
Even so I was able to have only a slight loss of signal quality at the receiver. Now, obviously, the scale of distances are magnitudes less, yes, but I remain unconvinced that these signals are intercept proof, not least the fact that the GPS differential calculation signal must start and end "somewhere" for the receiver/transmitter aircraft subsystem to point the datalink in the correct 4 dimensional position in the first place. YES?
Or perhaps not.