On Saturday, April 13, 2013 12:26:36 PM UTC-6, Bear wrote:
Bob,



I don't believe that we switch to GSM or whatever.



1. For none of the digital communication techniques it was possible to

find a global frequency range.



2. The relative speed is too high. To my knowledge the highest speed to

which a digital communication system is certified is 500 km/h (310 mph).

This is GSM-R, Global System for Mobile Communications - Railway or

GSM-Railway, for details see Wikipedia.

500km/h would be good enough for us but not for others. We can forget it

in aviation thanks to Doppler effect.



Bear

So, how is digital communication with 17,000 mph satellites possible with Doppler effects?

Nobody suggested GSM as an alternative to a global aviation-specific digital communications protocol.