Official U.S. government information about the
Global Positioning System (GPS) and related topics
Legacy Accuracy Improvement Initiative (L‑AII)
The Legacy Accuracy Improvement Initiative, completed in 2008, expanded the number of monitoring stations in the GPS operational control segment from six to 16. This tripled the amount of data collected on GPS satellite orbits, enabling a 10% to 15% improvement in the accuracy of the information broadcast from the GPS constellation.
The L-AII effort added 10 operational GPS monitoring stations owned and operated by the National Geospatial-Intelligence Agency (NGA). NGA originally fielded these sites to help it define the Earth reference frame used by GPS.
