GNSS Receiver Implementation on a DSP: Status, Challenges, and Prospects

A real-time GPS L1 C/A-code software receiver has been implemented on a Digital Signal Processor (DSP). The receiver exploits FFT-based techniques to perform autonomous acquisition down to a threshold of C/N0 = 33 dB-Hz. Efficient correlation algorithms and robust tracking loops enable the receiver to track an equivalent of 43 L1 C/A-code channels in real time with a tracking threshold of 25 dB-Hz. This accomplishment represents a milestone in an ongoing effort to develop a low-cost, flexible, and capable GNSS receiver for use as a scientific instrument and for GNSS receiver technology development. This paper reports on the current design and capability of the DSPbased receiver, provides an overview of the challenges that are particular to embedded GNSS software receiver design, and discusses the prospects of DSP-based GNSS software receivers in relation to the multiple frequencies and higher bandwidths offered by modernized GNSS.