UERE Analysis for Static Single Frequency Positioning Using Data of IGS Stations

摘要

This work analyses the measurements of major errors (ephemeris error, satellite clock error, ionospheric error, tropospheric error, multipath and receiver noise error), their correlation laws and their amplitude as functions of time and elevation angle for a static single frequency positioning receiver. The objective is double, first to give a better comprehension of the law of behaviour of error sources in a Global Navigation Satellite System (GNSS) and second to provide a measurement method for the User Equivalent Range Error (UERE). This method can be used as a tool for the estimation of accuracy in complex conditions (e.g. the impact of a correction model in the accuracy of a receiver during high ionosphere activity or the impact of an adaptive antenna for multipath mitigation in the global accuracy of a receiver) without the limitations of very constrained hypotheses usually made in standard UERE budgets i.e. decorrelation of individual errors, Gaussian centred distributions and same magnitude of UERE for every satellite on visibility. The method is based on the fundamental error equation directly derived from the observation equation expanded into Taylor series of the first order. From the fundamental error equation and the principle announced above, it is possible to measure what we define as the "Instantaneous Pseudo Range Error" (IPRE) for each step of time. The root mean square of the IPRE is exactly the UERE. The advantage of working at the IPRE level (instantaneous) rather than UERE level (RMS) is the assurance of using all the information available to provide properties of errors (amplitudes, correlations …). Geodesy, survey, traffic management or pedestrian navigation for example can profit from this method. It can also be used as input for integrity analysis.