Impact of Satellite Biases on the Position in Differential MFMC Applications

Abstract

Global navigation satellite systems (GNSS) are used in many applications and have been part of our daily life since years. In this work error contributions based on the satellite hardware have been investigated and their impact on safety critical applications has been assessed. The paper starts with an introduction of the measurement facility and analysis of the satellite payload imperfections as well as the impact of signal deformations on the pseudo-range for different GPS (Block IIF) and Galileo satellites. The analysis is based on in-phase (I) and quadrature-phase (Q) data captured with a high gain antenna, which offers almost interference and multipath-free signal reception. Using these measurements, the biases for different receiver parameters in terms of correlator spacing and bandwidth are derived. The differential code biases are estimated using a fixed configuration for the ground station, e.g. 0.1 chips for L1 and 1 chip for L5 as specified in the current DFMC MOPS (EUROCAE WG62) and 24 MHz (double-sided) bandwidth. For the user receiver, we extend the receiver parameters to the following design space: 0.01 - 1 chips correlator spacing and 2 – 50 MHz bandwidth for L1, 0.01 – 0.5 chips correlator spacing and 4 – 50 MHz bandwidth for E1, and 0.01 - 1 chips correlator spacing and 10 – 50 MHz bandwidth for and L5/E5a signals. In addition, an analysis of the magnitude of the differential satellite code biases and position errors within the design space defined for GPS L1 (RTCA DO-229E), and within the DFMC design space proposed in the DFMC SBAS MOPS (EUROCAE WG62) is shown. Based on the derived satellite differential code biases, the impact on the position solution for one location and different geometries is presented.