Global positioning system (GPS) software-defined receivers (SDRs) offer many advantages over their hardware-based counterparts, such as flexibility, modularity, and upgradability. A typical GPS receiver is readily expressible as a block diagram, making a graphical approach a natural choice for implementing GPS SDRs. This paper presents a real-time, graphical implementation of a GPS SDR, consisting of two modes: acquisition and tracking. The acquisition mode performs a two-dimensional fast Fourier transform (FFT)-based search over code offsets and Doppler frequencies. The carrier-aided code tracking mode consists of the following main building blocks: correlators, code and carrier phase detectors, code and carrier phase filters, a code generator, and a numerically-controlled oscillator. The presented GPS SDR provides an abstraction level that enables future research endeavors.

Cite and download the paper:
Z. Kassas, J. Bhatti, T. Humphreys, "A Graphical Approach to GPS Software-Defined Receiver Implementation," Proc. IEEE Global SIP, Austin, TX, 2013.