GNSS Software–Defined Radio

This chapter delves into the technical nuances of software-defined radio (SDR) as applied to Global Navigation Satellite Systems (GNSS). It begins by establishing the foundational concepts of SDR and its adaptation to GNSS technology. The chapter then progresses into the intricacies of signal acquisition, including both non-coherent and coherent signal integration methods. A detailed exploration of signal tracking is presented, covering tracking loops, discriminators, and their implementation. Unique to this chapter is the discussion on the application of baseband data without data decoding, introducing innovative methods like BGPS™ and RTK-B. These methods use AI genetic algorithms for instant positioning. The chapter also addresses the advantages of using long codes in new Global Positioning System (GPS) L2C and QZSS L-band Experimental (LEX) signals for code ambiguity resolution. The chapter transitions into decoding data and forming observables, detailing lock detectors, bit synchronization, and algorithms for constructing GNSS pseudorange measurements. The final section focuses on real-time implementation aspects of GNSS SDR, encompassing RF signal post-processing, concurrency, and operation speed, thus providing a comprehensive understanding of the practical and theoretical aspects of GNSS SDR.