This book is the result of one-year investigation in all the available technologies necessary to build an efficient navigation system usable on rovers moving on the ground and at the sea, centered on GNSS (Global Navigation Satellite System). It is used as instruction note for the calls for tender in the Italian Space Agency. It targets the applications of automated and autonomous navigation for the following types of rover: trains at level 2 of ERTMS/ETCS—autonomous cars, starting from level 3 of SAE -MASS (Maritime Autonomous Surface Ships) at level 4 of IMO. The material is already edited for the using of professionals and engineers who need to build a navigation system on top of COTS hardware. The topics cover in a thorough view all the necessary subjects to build an efficient positioning system for the rover enabling coping with all kind of environments and all interferences and always warranting a minimum level of the positioning KPIs (reliability, availability, integrity, and accuracy). The localization system built according to these guidelines will be ready to be certified and the product will be at TRL 6 (i.e., technology demonstrated in the relevant environment).