Software-Defined Radio Technologies for GNSS Receivers: A Tutorial Approach to a Simple Design and Implementation

The field of satellite navigation has witnessed theadvent of a number of new systems and technologies: afterthe landmark design and development of the Global PositioningSystem (GPS), a number of new independent Global NavigationSatellite Systems (GNSSs) were or are beingdeveloped all over the world: Russia's GLONASS, Europe'sGALILEO, and China's BEIDOU-2, to mention a few. In this ever-changing context, the availability of reliable and flexible receivers is becoming a priority for a host ofapplications, including research, commercial, civil, and military.Flexible means here both easily upgradeable for future needsand/or on-the-fly reprogrammable to adapt to different signalformats. An effective approach to meet these design goals is thesoftware-defined radio (SDR) paradigm. In the last few years, theavailability of new processors with high computational powerenabled the development of (fully) software receivers whoseperformance is comparable to or better than that of conventionalhardware devices, while providing all the advantages of a flexibleand fully configurable architecture. The aim of this tutorial paperis surveying the issue of the general architecture and designrules of a GNSS software receiver, through a comprehensivediscussion of some techniques and algorithms, typically appliedin simple PC-based receiver implementations