MONITORING STATION LOCATION DETERMINATION FOR A SATELLITE NAVIGATION SYSTEM

In a global positioning system, satellites transmit navigation signals to users which determine their position from the received navigation signals. A wide area differential correction system employs receiving stations in fixed positions on the ground and compares ranges between the receiving stations and the satellites measured from the navigation signals with the actual ranges between the satellites and the receiving stations to determine correction information including corrections in the satellite clock times and the satellite positions to be transmitted to the users and from which the users can more accurately determine their positions. The site locations of the receiving stations to be used in the wide area differential correction system are determined by first determining an initial estimate of the site locations by means of a global positioning system and storing these initial estimates in a data base and then removing each receiving station from the wide area differential correction system in turn and calculating the wide area differential corrections without use of the site location of the removed receiving station. The site location of the removed station is then determined using the global positioning system and the wide area differential calculations and the site location of the removed station is updated in the data base with the site location thus determined. This process is repeated for each receiving station in turn three times to determine an accurate updated data base of site locations for the receiving stations to be used in the wide area differential correction system.