Real-time corrections at the decimeter level over an entire continent? The challenge lies in minimizing the ranging errors from signals propagating through the Earth’s atmosphere. European researchers describe how it can be done using a Wide Area Real-Time Kinematic concept that exploits the full geometry of the observations, a central processing facility, and undifferenced processing of measurements from widely space GNSS reference receivers to create a real-time ionospheric model of the signal slant delays.