Real-Time Differential GPS Error Modelling in Regional Reference Station Networks

Observations of several GPS reference receivers in a regional network enable two kinds of error modelling and reduction. The spatially correlated errors (orbit, ionosphere, troposphere) are modelled epoch-by-epoch and satellite-by-satellite by 2-D linear interpolation. Furthermore, multipath effects are mitigated by averaging correspondent observations of several receivers. As a result, observations of a virtual reference station are created. It is assumed to be located at the rover’s approximate position and its observations are used in the precise baseline positioning of the rover. This approach has been tested with several months of observations including data disturbed by ionospheric irregularities, large tropospheric gradients and large orbit errors. It considerably improved ambiguity resolution and reduced coordinate errors in the positioning of rover receivers.