[adx]

Any idea on how fast these drones are? IIRC, don't commercial GPSs cut out if the receiver is moving too quickly (built in to prevent the use of commercial GPS for this very thing?)? Also, I'd probably use more than one means of getting positional data (like RinaseaofDs wrote, use Loran C or a similar radio direction-finding method). The skill level needed to do systems integration is pretty much EE undergrad/entry-level BSEE stuff.

[mumbo]

...the receiver is moving too quickly (built in to prevent the use of commercial GPS for this very thing?)?

Nope. Mine works in commercial jetliners.

[Myrddin]

IIRC, don't commercial GPSs cut out if the receiver is moving too quickly (built in to prevent the use of commercial GPS for this very thing?

Most commercial GPS units contain 12 parallel receivers. Units intended for use by terrestrial vehicles are usually rated to about 93 knots. You can purchase more expensive units with faster processors for use in an aircraft. Part of the reason for the encrypted channel on the GPS service is the provision of data at 10 times the rate of the C/A channel that is available to civilians. The higher data rate is required to support fast moving vehicles.