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The GRAS radio occultation instrument on board MetOp has continuously provided measurement data during almost four years. The measurement data are here used as a means to analyze the signal tracking performance of the GRAS instrument. The results demonstrate that the atmospheric Doppler shift is measured to an accuracy of 1.1 mm/s and that the on-board Doppler model is accurate within 4 m/s (or 20...
This paper proposes an improved implementation of the subspace projection method aiming to minimize the near-far effect that occurs in Global Navigation Satellite System receivers. Our technique does not demand phase estimation of the strong signals, thus being suitable for non-coherent receivers. Simulation results demonstrate the effectiveness and the limitations of the proposed mitigation technique.
The use of GNSS receivers for on-board satellite orbit determination has become a common solution in new satellite design, as it considerably simplifies the overall architecture if compared to traditional orbit determination systems. Different challenges have to be faced while designing a GNSS system for these applications, since in general the terrestrial receivers are not designed to guarantee their...
One of the current limitations to evaluate the impact of a realistic multipath environment over a GNSS receiver is the high number of multipath rays that are needed to model the channel in a HW RF constellation simulator. That makes necessary the application of reduction techniques to decrease the number of channels per satellite to be simulated. The initial evaluation of two reduction techniques...
The performance of the Space Alternating Generalized Expectation Maximisation (SAGE) algorithm for multipath mitigation is assessed in this paper. Numerical simulations have already proven the potential of SAGE in navigation context, but practical aspects of the implementation of such a technique in a GNSS receiver are the topic for further investigation. In this paper, we will present the first results...
In this paper we present the Acquisition Speed Up Engine (ACSE) algorithm, devised in 2007 by Thales Alenia Space in the framework of studies for the GIRASOLE receiver and implemented by Consorzio Pisa Ricerche. The algorithm is used to fast detect the presence of a CDMA signal in a time/frequency uncertainty domain. This is made possible with a serial/parallel approach and a modified FFT algorithm...
This article presents a methodology related to the computation of civil aviation acquisition, tracking and data demodulation thresholds adapted to the case of Galileo E1 OS/SoL signal. These thresholds are compared against worst case link budgets representing operational scenarios. It is shown that these thresholds provide a positive margin although these theoretical results would probably require...
This paper contains selected test results of an indoor positioning prototype system making use of GPS/Galileo signals on L1/E1 and L5/E5a in addition to WiFi data, ZigBee data and a MEMS-based dead reckoning algorithm called pedestrian navigation system (PNS). The system uses a partially coherent ultra-tightly coupled integration scheme. The GNSS signal processing (acquisition and tracking) supports...
The aim of this paper is to present an acquisition strategy for Global Navigation Satellite System (GNSS) signals exploiting aiding information provided by GNSS receivers in a Peer-to-Peer (P2P) positioning system. This work sheds light on the benefits of sharing information regarding the received satellite signal power: the Carrier-to-Noise density ratio (C/N0) estimated by aiding peers relatively...
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