Aided and Augmentation Systems: Differential GPS, Pseudolites, Ground-Based Augmentation Systems, and Space-Based Augmentation Systems

There are several systems in place to improve the quality and reliability of these PNT systems. These were originally ground-based but are today largely space-based. These rely upon on a technique referred to as Differential GPS, or DGPS. These were originally developed to defeat Selective Availability, and to provide higher precision in applications such as civil aviation that require both higher precision as well as integrity monitoring that are not provided in the basic signals. In this chapter we present ground-based and space-based differential correction systems including the U.S. Wide Area Augmentation System and the several international systems, as well as augmented systems and pseudolites, and related systems. The chapter concludes with a presentation of kinematic GPS techniques.