Hi stepwilk,
It would not be pure satnav velocity or inertial velocity. That is where the engineering comes in. You generate a computer model of the wind vector, and generate an airspeed validation system (computerized like everything else on the aircraft). The system is looking for any input parameter that is changing faster than preset rates determined by experience. The rates can be adjusted for condition of flight.
The key thing you are trying to avoid with the system is things like a sudden drop off to 0 airspeed or surge to Mach 1.5. Just trying to keep things in the ball park.
Now does it make sense?
Sid