SDR Technology Applied to Galileo Receivers

It has been worldwide recognized that under the push of the research activity related to Galileo and to the future GPS (Global Positioning System), the satellite navigation market is growing in importance for different civil applications. In order to deal with future developments and improvements of GNSS, advanced receiver architectures providing the enhanced performances will be needed. For these reasons, it is interesting to devise smart approaches to the design of navigation receivers assuring a certain degree of reconfigurability and portability in order to deal with new GNSS scenarios (e.g., integration between navigation and communication services). In this paper we discuss a receiver architecture based on Software Defined Radio (SDR) technique. The main peculiarity of SDR is to allow for developing of flexible devices in which the receiver functionalities are softwareimplemented in a modular architecture. The present technology does not allow a totally software receiver, but the development of fast and reliable electronics make the SDR approach an interesting perspective. Note that great attention has been devoted to the applicability of SDR techniques in order to design reconfigurable personal communication terminals, leaving unexplored the potentialities of SDR for other terminals as navigation receiver, or integrated hybrid communications/navigation receivers. The main objective of this work is to explore innovative approaches and new technologies in the area of satellite navigation receivers that will allow satisfying the needs and the constraints of future application, presenting the main advantages given by the availability of a SDR navigation terminal. As example, the possibility to design an efficient M-code receiver (based on Binary Offset Carrier modulation – BOC) has been analyzed: on the basis of the Galileo SIS definition (Signal-In-Space), the SDR approach can be used in order to implement a modular structure compliant with an open system architecture concept, based upon high sampling rate Analog to Digital Converters (A/D), reconfigurable hardware (Field Programmable Gate Array - FPGA) and high speed Digital Signal Processors (DSP