A method for increasing GPS working area

The need for precise position and navigation aids in many areas of industry is becoming increasingly apparent. The driving force for this is our ability to determine the location of objects or features of the physical environment for use in map or chart making, and database development. The GPS represents one of the main systems for navigation aids. However, there are many errors associated with the navigation solution of the GPS. The selective availability (SA) error is considered as one of the major errors in the GPS. This error would take the user outside of the 100 m 2D root mean square circle. DGPS is used to increase the system accuracy due to SA error and other sources. In this paper, a method is used to increase the GPS working area through modification of position lines. SA simulation is used to evaluate the error reduction and GPS area