Chapter 6GNSS Positioning Approaches

New GNSS positioning and timing techniques continue to be developed and refined. Whereas during the formative years the progress of GPS positioning was measured by leaps and bounds at a breathtaking speed, the current developments are more incremental in nature but, nevertheless, lead to noticeable refinements that result in shortening of observation time, increase in accuracy, and increase in reliability. The incremental improvements are due to the modernization of GPS, the repopulation of the GLONASS satellite system, and the new Beidou, Galileo, and QZSS satellite systems. Equally important to continued improvement of GNSS positioning is the dedicated efforts by many scientists and engineers to complete a GNSS infrastructure for data collection, evaluation, and user service. Examples include the IGS (International GNSS Service), which provides various intermediary products, antenna calibration services, services that provide accurate information about the ionosphere and troposphere, and also processing services that accept user observations and deliver final coordinates in any desired coordinate system.

The first section summarizes undifferenced pseudorange and carrier phase functions between a single station and single satellite. This includes the triple-frequency functions. This is followed by functions that include two stations. These are the single differences, consisting of the across-receiver functions, across-satellite functions, ...

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