Drones are taking the world by storm and revolutionizing applications including delivery, surveillance, inspection, and mapping. As drones become more commonplace, operating in urban areas or carrying out critical missions, the aspect of reliability and resilience becomes increasingly important. To ensure overall system resilience key components need to account for their vulnerabilities. GPS/GNSS receivers used for UAV navigation need to be protected by anti-jamming and anti-spoofing technology, which is compatible with autopilots to easily fit into the UAV ecosystem.