Self-correcting differential global positioning system

Abstract

The Global Positioning System (GPS) is a satellite based system that can accurately determine a user's position in terms of latitude, longitude, and height or in terms of X, Y, and Z. The X, Y, and Z coordinate system is an Earth Centered Earth Fixed (ECEF) coordinate system. After the basics of the Global Positioning System are discussed, the Differential Global Positioning System (DGPS) will be introduced. The DGPS is GPS using two receivers. One receiver is on a known position and sends corrections to another receiver. The next topic is the Self-Correcting Differential Global Positioning System (SDGPS). This is a form of DGPS which requires only one receiver. The SCDGPS depends partly on the Selective Availability (SA) which is a random error introduced into the GPS signal to deny civilian users accuracy. The error will not exceed 100 meters. An algorithm is presented which significantly reduces the error that is present in the normal DGPS. Both the favorable and unfavorable results are discussed. Since the data collection process did not allow benchmarks to be found with centimeter grade accuracy, a program simulation was written. The program was used to verify the accuracy of the SCDGPS algorithm by allowing the user to input simulated benchmarks so the exact error from each position after the correction could be determined