Supercorrelation: Enhancing the Accuracy and Sensitivity of Consumer GNSS Receivers with a DSP Upgrade

Ramsey Faragher, Nicolas Couronneau, Matthew Powe, Paulo Esteves, Mark Crockett, Henry Martin, Emanuele Ziglioli, Chris Higgins, and Darren Buckle

Abstract: Focal Point Positioning has developed new signal processing methods for the correlation stage of a GNSS receiver that enable many seconds of coherent integration while the receiver system is undergoing dynamic motions. These innovative methods have been successfully trialled using low-cost, consumer-grade receivers such as those found within smartphones. We will be showing our latest real world results from a variety of tests in a variety of locations, explaining how our signal processing techniques work, including our newest Ultracorrelation technique, and we will explain how these methods can be implemented into current chipset designs. Objectives: These new signal processing stages change the correlators from the “textbook” PRN sequences into a particular pattern of phase correcting sequences that account for receiver motion and local clock variations. The resulting Supercorrelator couples strongly (coherently) to the line-of-sight energy coming from each satellite, but simultaneously attenuates energy arriving at the antenna from non line of sight directions. The result is high gain on the line of sight energy, and the mitigation of multipath interference before the creation of the correlation peak. Note that this is all in software, we make no hardware changes, nor do we require new antennas. Results: We will show the results of walking and driving tests in a variety of locations and will demonstrate the tracking of GNSS signals deep indoors using our Supercorrelation and Ultracorrelation techniques. We will also demonstrate our sky scan technology which can directly image the angular arrival of energy from the line of sight, and separately from reflected signals, again just using a single moving antenna and standard consumer grade sensing. Key innovations: The Supercorrelation technique is the next generation step beyond deep-coupling of inertial measurements and GNSS. We will also explain how our new Ultracorrelation technique works, which can extend the coherent integration time out to 5 seconds and more, even on moving low-cost consumer devices with uncompensated crystals. Significance: Supercorrelation and Ultracorrelation provide clear improvements to existing GNSS receiver designs through software upgrades to the DSP stage in current generation GNSS chipsets. The technologies will have a significant impact on the performance of consumer GNSS receivers in urban environments once deployed by our customer GNSS chipset manufacturers.
Published in: Proceedings of the 31st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2018)
September 24 - 28, 2018
Hyatt Regency Miami
Miami, Florida
Pages: 357 - 375
Cite this article: Faragher, Ramsey, Couronneau, Nicolas, Powe, Matthew, Esteves, Paulo, Crockett, Mark, Martin, Henry, Ziglioli, Emanuele, Higgins, Chris, Buckle, Darren, "Supercorrelation: Enhancing the Accuracy and Sensitivity of Consumer GNSS Receivers with a DSP Upgrade," Proceedings of the 31st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2018), Miami, Florida, September 2018, pp. 357-375.
https://doi.org/10.33012/2018.15823
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