Summary: You an mix the coordinates obtained from celestial navigation (stars) with signals of opportunity (Electromagnetic sources like FM) to find the position without GPS.
Problems: Anytime a military advertisement happens (LN-120G Stellar-Inertial-GPS from Northup G.) - if you don't see the total price of the unit, know that it was a waste of money and resources.
Problems: Anytime a military advertisement happens (LN-120G Stellar-Inertial-GPS from Northup G.) - if you don't see the total price of the unit, know that it was a waste of money and resources.