Everything You Never Knew You Needed to Know About Differential and Precise Point Positioning
DGNSS improves GNSS accuracy by using stationary reference receivers to broadcast corrections to rovers, transforming standalone GPS accuracy from about 5–15 m to sub-meter or centimeter levels, with SBAS like WAAS (USA) and EGNOS (Europe) delivering about 1–3 m for aviation. Real-Time Kinematic (RTK) uses carrier-phase measurements and double-differencing to fix integer ambiguities, delivering centimeter-level accuracy in real time, with highest performance when the base is within about 10–20 km. Early differential GPS (DGPS) yielded about 1 meter accuracy within tens of kilometers of the base, with degradation of roughly 1 m per 150 km. Precise Point Positioning (PPP) provides
