Relative Positioning and Real‐Time Kinematic (RTK)

This chapter describes the concepts and theory involved in relative global navigation satellite system (GNSS) positioning and navigation. It begins by describing the concepts and advantages of relative positioning in contrast to point positioning, and the conceptual and terminological similarities and differences between differential and relative positioning. A brief description of the generic GNSS observables used and a catalog of measurement errors are then provided, in order to present the necessary mathematical modeling and relative baseline estimation. Central to precise relative positioning is carrier-phase integer ambiguity resolution, which is described, along with an algorithmic case study. All of these concepts are brought together to create real-time kinematic (RTK) processing, as well as the follow-on network RTK processing. The chapter concludes with a discussion of recent developments in relative positioning in terms of additional signals, multi-constellations, and multi-processing modes, such as network RTK combined with precise point positioning.