The simulation updates orbit positions of the GPS satellites augmented by four geosynchronous spacecraft. For each resulting geometry, satellite geometry for all WRS's is determined. The simulation then loops through a grid of user positions. Ionosphere errors are handled by a separate covariance algorithm running in parallel. The user then computes a weighted least-squares position and finds his expected 1s position error from the resulting covariance.
Availability is tabulated for each user position, as is the maximum availability outage period.
Results presented for the Stanford 3-WRS experimental WAAS network show that the Stanford WAAS meets this accuracy requirement over a large area. The results also validate the observed vertical errors from Stanford s WAAS flight trials.