Worst Impact of Pseudorange nominal Bias on the Position in a Civil Aviation Context

Jean-Baptiste Pagot (1) , Olivier Julien (1) , Yoan Gregoire (2)

1 ENAC - Ecole Nationale de l'Aviation Civile
2 CNES - Centre National d'Études Spatiales [Toulouse]

The objective of this paper is to investigate the impact of nominal biases that affect code pseudorange measurements on GNSS signals. This impact is looked at position level, in a civil aviation context, considering that a least square algorithm is used to estimate the position from pseudorange measurements. As an input to this work, it is assumed that the pseudorange nominal biases can be written as the sum of three components following the proposition made in [1]: - Delays induced by the satellite antenna. - Delays induced by the receiver antenna. - Distortions induced by the satellite payload, the satellite antenna and the receiver antenna. One important feature of those models is that they are dependent upon: - the satellite antenna nadir (angle between the satellite/centre of the Earth line and the satellite/user line) and/or - the satellite elevation and azimuth with respect to the user. By consequence a pseudorange nominal bias is dependent upon the relative position between the user and the satellite. The two main contributions of this publication are: - The proposition of three models that are able to characterize the three code pseudorange nominal bias components. These models are based on a wide review of the state- of-the-art regarding each bias source reported on GPS L1 C/A signals. - The estimation of the impact on the position of code pseudorange biases considering proposed nominal bias models. To take into account that pseudorange nominal biases are dependent upon the relative position between the user and the satellites, this estimation is made at different locations around the world and at different epochs using realistic orbital parameters to reproduce constellation geometries. A worst case is provided for each location, and corresponds to the maximum absolute position error obtained during a period of 24 hours (position biases are assessed every 2 minutes).

Domaines: Traitement du signal et de l'image [eess.SP]

Jean-Baptiste Pagot, Olivier Julien, Yoan Gregoire. Worst Impact of Pseudorange nominal Bias on the Position in a Civil Aviation Context. ITSNT 2017, 4th International Technical Symposium on Navigation and Timing, Nov 2017, Toulouse, France. ⟨hal-01759302⟩