Which term describes a system that improves the accuracy of Global Navigation Satellite Systems by providing satellite positioning corrections?

• A. Differential Global Positioning System (DGPS)
• B. Differential pressure
• C. Direct indication
• D. DUATS

Answer: (A)

DGPS provides differential corrections to GPS signals, allowing satellite positioning data to be refined and made more accurate. Ground reference stations with precisely known locations monitor GPS signals and determine the discrepancy between the measured and true positions. They then broadcast correction data to other receivers, which apply these corrections to their GPS calculations. This process reduces errors from satellite orbits, clock differences, and atmospheric effects, typically improving horizontal accuracy to a few meters or better, depending on the system and coverage.

Differential pressure, on the other hand, relates to the pitot-static system used for airspeed and altitude, not satellite navigation corrections. Direct indication is not a term used for GNSS corrections, and DUATS is a flight-planning service rather than a positioning correction system.