Positioning Model

Abstract

The focus of this chapter is on the models for positioning. Since the global navigation satellite system (GNSS) observation equations are nonlinear in the position coordinates, the chapter is started with a section on the linearization of the observation equations for pseudorange (code) and carrier-phase. After that, absolute (point) positioning models are discussed, starting with the code-based single point positioning (SPP) model, followed by the model for precise point positioning (PPP), based on code and phase. The relative positioning models can be distinguished into code-dominated (differential GNSS or DGNSS) models and phase-dominated (real-time kinematic or RTK) models. For the latter type of models, a general multifrequency undifferenced model is presented, which may form the basis of both relative network model and the (absolute) model that enables PPP users to perform integer ambiguity resolution (PPP-RTK). After that the link is made between the undifferenced model and the single and double differenced versions of the positioning model and an overview is given of the various positioning concepts.