Create a GPS receiver that detects spoofing by adding logic to track anomalies and utilize redundant GPS satellites to cross check signals.
Spoofing the GPS signal requires that it send multiple signals that represent multiple satellites. If a GPS receiver tracks more satellites that it needs for location, it can decide which to use and use the other signals to cross check for accuracy. To make the spoofing seamless it must know the current location of the receiver and simulate a change in direction. It is very difficult to make this seamless. Some type of anomaly would occur. Enhance GPS receiver software to detect anomalies and use additional satellites for verification. Adding more GPS satellites will help facilitate that.