Influence of the GNSS satellite elevation to the position error

Increasing progress in the field of Global Navigation Satellite Systems (GNSS) in recent decades supports the effort to use it for the determination of train position for railway safety-related systems. The possibility of the detection of a GNSS horizontal position error based on the relation between vertical and horizontal position errors was investigated. The possibility of using values of altitude for the estimation of the position error in the horizontal plane was discussed. This is proposed in order to increasing the integrity of GNSS-based position determination. The analysis of pseudorange errors of satellites with different elevations to final computed position was done. The analysis was done by the simulation of multipath errors in pseudoranges. It was done by simulation with software receiver Pegasus made by Eurocontrol. The simulations were based on real EGNOS data, which were measured by means of Septentrio PolaRx3 receiver in Pardubice in Czech Republic.