Ch 19. Relative Positioning and Real‐Time Kinematic (RTK)

Chapter Overview:

Relative positioning and Real-Time Kinematic (RTK) are industry-standard precise GNSS processing techniques that allow standard meter-level GNSS positioning and navigation to be enhanced to the centimeter and even millimeter level. This chapter provides an overview of these techniques from the concepts to implementation to performance. The concept of relative GNSS positioning is developed from differential positioning and the mitigation of spatiotemporal measurement errors. The key GNSS observables, pseudorange and carrier-phase, are presented and their parameterization models defined. Measurement errors are described in the categories of transmission, propagation and reception in order to explain the existing positioning estimation challenges. Relative positioning mathematical modeling is derived in the form of single-, double- and triple-differencing of the observables. The section ends by describing the estimation process and positioning performance. The next section describes carrier-phase ambiguity resolution, including a case study of the LAMDBA method. The typical estimation process is presented, along with an RTK performance analysis and communications considerations. Network RTK is then described, building on the earlier concepts and providing details on the reference station processing, correction generation approaches, correction interpolation and performance. The chapter ends with a discussion of recent developments in relative positioning and RTK, including multi-constellation processing, network RTK combined with other processing and future considerations.

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