Tracking Error Modeling in Presence of Satellite Imperfections

Kurzfassung

Modeling both nominal distortions and signal anomalies (i.e. Evil waveforms, ICAO threat models) is crucial for an accurate user error budget for SBAS and GBAS (multi- frequency, multi-constellation). Such analysis of particu- lar interest for the ongoing standardization work of L1- L5 SBAS services. In this paper we propose a method to jointly estimate the analogue and the digital distortions. This comes very useful in those cases in which the esti- mates of the two satellite imperfections are interdependent, e.g. when the time-bandwidth product is small. The impact of both satellite imperfections on the ranging performance of a GNSS receiver is assessed by means of analytical for- mulas which make use of the Cross-Power Spectrum (CPS) between the distorted and the ideal signal, and of the Power Spectral Density (PSD) of the nominal (ideal) signal.