Navigation Algorithm Optimisation for Combined Galileo/GPS Receivers with the GRANADA Environment and Navigation Simulator

Antonio Fernández, Paolo D'Angelo, José Diez, Livio Marradi and Vincent Gabaglio

Abstract:	The Galileo Receiver ANAlysis and Design Application (GRANADA) SW Receiver simulator is one of the reference SW tool for receiver and application developers. It has been developed in the frame of the GAlileo Receiver Development Activities (GARDA) of the European Commission 6th Framework Programme for the Galileo Joint Undertaking (GJU). GRANADA, developed by Deimos Space under Alenia Spazio specification, is composed of two complementary tools: a Bit-True SW Receiver simulation, that recreates in detail the signal processing chain of a Galileo receiver [1], and the GNSS Environment and Navigation Simulator, subject of this paper. This tool, implemented in C-code with an advanced TCL/TK user interface, is being used by application developers who need external access to raw data (i.e. pseudorange and carrier phase), hence acting as a Raw Data Generator (RGD), and to the PVT solution products. It includes realistic characterisation of the effect of the different error components depending on the type of terminal and GNSS receiver configuration. It is possible to configure the GNSS constellation (both Galileo and GPS), the environment conditions, satellites and receiver characteristics, and the navigation algorithms. The simulator runs on a standard Windows PC, allowing the maximum use from people not involved in the development. The simulator architecture is based on GARSIM (Galileo Receiver Simulator), also developed by Deimos and Alenia Spazio, under ESA contract, for the Pre-development of the Galileo Ground Segment Reference Receiver [2]. In this paper, a performance and visibility analysis of different receiver combining Galileo and GPS using the GRANADA simulator are presented. The analysis has been focused on visibility and Dilution of Precision (DOP), which is the key parameter that allows to transfer the User Equivalent Range Error (UERE) into a navigation error. Given a maximum number of channels, the useful satellites of the system are retrieved from all the visible ones, using a selection criterion based on different algorithms: from a simple maximum elevation criterion, to the quasi-DOP optimisation performed in GRANADA as baseline, including a new algorithm (“dartboard” selection) described in this paper. For a particular geometry of the GNSS constellations, different scenarios have been studied, depending on the characteristics of the environment (from open-field, the so-called rural pedestrian environment, to the urban canyon, modelled as a 40º masking angle) and the receiver. The system performances, in terms of visibility, DOP, and navigation reliability have been analysed as a function of the environment and the number of channels. Performances are compared with a Galileo-only and with a GPS-only receiver.
Published in:	Proceedings of the 18th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2005) September 13 - 16, 2005 Long Beach Convention Center Long Beach, CA
Pages:	1939 - 1944
Cite this article:	Fernández, Antonio, D'Angelo, Paolo, Diez, José, Marradi, Livio, Gabaglio, Vincent, "Navigation Algorithm Optimisation for Combined Galileo/GPS Receivers with the GRANADA Environment and Navigation Simulator," Proceedings of the 18th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2005), Long Beach, CA, September 2005, pp. 1939-1944.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In