Itaca: a Fully Software GNSS Receiver Platform for Innovation Development

The increased use of digital technology in the design of Global Navigation Satellite Systems (GNSS) is resulting in more functions and blocks that are being implemented by means of software routines. From a theoretical point of view the Software Defined Radio (SDR) approach represents the possibility to design flexible systems, which can be reprogrammed and thus upgraded almost instantaneously. Considering that the advent of the Galileo system in Europe, the modernization plans for Global Positioning System (GPS) and the novel signal processing algorithms that are everyday proposed, flexibility in the design would allow the upgrade of the receiver in order to improve the processing of GNSS signals (e.g. multipath rejection, different demodulation schemes, etc). This paper will present a software receiver named Itaca which has been developed at the Navigation Lab of Istituto Superiore Mario Boella and Politecnico di Torino. This receiver implements a GNSS receiver (GPS and Galileo-ready) that runs on a Personal Computer (PC) without the need of devoted hardware used for navigation purposes. Such a platform is intended to be a flexible tool for testing new solutions and algorithms in a real receiver architecture (from Acquisition to PVT computation) and able also to deal with real signals. The modular architecture of Itaca receiver allows acquiring and tracking more than twenty parallel channels with sampling frequencies up to twenty megahertz; the unique hardware blocks needed are just an external antenna and the analogue front end. Each channel could work with different incoming signal like GPS, Galileo, SBAS satellites as well as the first Galileo satellites GIOVE-A handling all the various modulation schemes according to the public Interface Control Documents (ICDs). Thanks to the receiver modular architecture it is possible to reach the same positioning performances of a mass-market receiver, but with the advantages of a very high flexibility required to development and test of novel algorithms. Finally the paper will show the performance of the receiver when connected to an internally developed front-end based on Components Off The Shell (COTS).