Implementation Strategies for a Software-Compensated FFT-based Generic Acquisition Architecture with Minimal FPGA Resources

Marc-Antoine Fortin, Francis Bourdeau, René Jr. Landry

Peer Reviewed

Abstract: A generic 2048-point FFTacquisition architecture is proposed to address L1 civil signals from all four GNSS constellations. After emphasizing hardware design criteria and their resulting design limitations, software compensation approaches are compared. A detailed validation methodology, involving a successive 1000-step Monte-Carlo study, was defined to optimally configure the acquisition channel, with new metrics to establish formal signal detection. The integration thereof results in a novel, minimalistic, yet generic, acquisition channel implementation, as well as a thorough validation method. Execution time of one acquisition iteration is approximately 5 ms, in line with VHDL simulations and foreseen channel management overhead. Coarse/fine search increments and thresholds are based on extensive experimentation. A 41 dB-Hz acquisition sensitivity threshold was established to achieve >95% detection rates for 1ms integrations, while 15ms non-coherent integrations are required for signal strengths down to 37 dB-Hz. These thresholds account for known implementation losses.
Published in: NAVIGATION: Journal of the Institute of Navigation, Volume 62, Number 3
Pages: 171 - 188
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