Initial Results for Dual Constellation Dual-frequency Multipath Models

Abstract

In this paper we present the initial results obtained from flight campaigns conducted within DUFMAN on Airbus commercial aircraft. The measurements are collected from prototypes of dual-frequency multi-constellation avionics receiver and the antenna installed on the aircraft has been selected to meet at best the current dual-frequency dual-constellation antenna requirements. In addition to the initial results obtained from avionics hardware, the impact of the different receiver correlator spacing and bandwidth is investigated and discussed.

Antenna Group Delay Variation Bias Effect on Advanced RAIM

“…For the dual-frequency based ARAIM, variances for each measurement, , are constructed by considering the satellite ephemeris and clock error, tropospheric error, and code noise and multipath error components [5]. The bias effect should be considered in addition to the existing error components in (7) to construct the projection from the measurement domain to the position domain as follows.…”

“…In the rest of the paper, for simplicity, we assume the state of interest as the vertical position coordinate. In (8), the error vector, , contains the error sources considered within the measurement error model in (7). As shown in (8), since the projection via the matrix is a linear transformation, if the antenna error, represented as , is statistically independent of in the range domain, they are also independent in the position domain.…”

“…Thus, the inflation by a factor of 1.45 is needed for the inflated distribution (red curve) that overbounds the empirical one (blue curve), as shown in the right figure. In addition to the position error distributions, we need to consider the AGDV bias effect on the fault detection threshold, in (9). The ARAIM fault detection threshold, , for the fault mode is determined based on the standard deviation of the solution separation (SS), σ , , as shown in (11).…”

“…Within the Dual Frequency Multipath Model for Aviation (DUFMAN) project funded by European Commission, dual-frequency, dual-constellation (DFDC) airborne multipath models were developed by collecting GPS and Galileo measurements from several test flights using aviation GNSS antenna and receivers [6], [7]. The multipath error models were derived by characterizing the errors introduced by the user antenna biases for the antennas used during the flights and separating their contribution from the observed multipath errors.…”

“…For this purpose, user-satellite geometries are first simulated based on 24 GPS/Galileo constellations and a predefined global user grid formation for ten sidereal days, which corresponds to the repetition period of the Galileo constellation [3]. Next, user AGDV errors in signals propagated to the users are computed based on actual antenna measurements as presented in our previous investigation [9], [10]. In this study, we take two different approaches to the assessment of the AGDV range errors and the new multipath model effect on ARAIM performance: measurement and position domain characterization of the AGDV errors.…”