To maintain accuracy, GPS satellites require regular corrections to their broadcast orbital parameters. An extensive network of ground antennas and control stations throughout the world periodically updates the satellites’ orbital parameters, and transmits the updated information to each satellite. Currently, this process occurs at least once a day. Raising the update frequency would increase the accuracy of GPS, but would increase network traffic within the ground network with unknown consequences. To test the impact of such changes on network load, the Clinic team has developed a simulation framework using inexpensive PCs to represent the various nodes in the ground network.