Final answer:
At least four satellites are necessary to obtain a 3D position fix in GPS navigation, as they provide the required data for accurate triangulation and altitude information.
Step-by-step explanation:
For obtaining a 3D position fix using Global Positioning System (GPS) technology, a minimum of four satellites are required. These satellites are part of a network that operates based on precise atomic clock synchronization and relativity principles to provide accurate location data. While a network of three satellites can locate positions for about half of all possible locations in the sky, a fourth satellite is essential to resolve ambiguities and provide the additional data needed for the altitude component, hence enabling three-dimensional positioning. The complex system of orbiting satellites ensures that at any given time, a GPS receiver on Earth can establish a line-of-sight with at least four satellites, allowing for the calculation of an accurate 3D position.