Satellite navigation signals are very weak after travelling from the satellite transmitter to the user receiver antenna on the Earth and are extremely vulnerable to unintentional and intentional, malicious interference. A serious concern nowadays is the increase in the amount of jammer devices due to the severe threat they pose to many applications relying on satellite positioning. Jammers may cause serious damage if their signals are not properly detected and the effects mitigated. This project analyses the effects of intentional interference on satellite based positioning, methods for interference detection and risk management of satellite navigation jamming, and develops methods for mitigating the effects. The project researches jammer signal properties, the interference resistance of future GNSS signals, and develops weak signal acquisition and tracking as well as reliability testing algorithms suitable for situations when interfering signals are present in order to improve positioning accuracy and availability.