Dual Frequency Mass-market Chips: Test Results and Ways to Optimize PVT Performance

Paolo Crosta, Paolo Zoccarato, Rafael Lucas, G. De Pasquale

Abstract:	Abstract Following recent hype for improving accuracy of the position fix provided by mass-market GNSS receivers, a new generation of mass-market chips based on dual or triple frequency measurements is next to be commercialized. The introduction of multiconstellation chips working on L1 has shown on one hand the great improvement of such a solution in terms of Time-To-First-Fix (TTFF) and Dilution of Precision in difficult environments. Problems arise where the availability of many measurements is hard (e.g. urban canyons) or where the antenna characteristics and the interactions with the users degrade the quality and the power of the received signals (e.g. smartphones). On the other hand, the tests of single frequency chips with up to four constellations have not shown enough accuracy as it is currently aimed at. The natural evolution of this trend is the addition of a second frequency at first and multiple frequencies as further steps. The time is also right for this choice because of the current constellation status with for example GPS and Galileo constellations providing a sufficient number of satellites in the L5/E5a frequency bands. Whilst the receiver evolution is quite clear since most mass-market manufacturers have already developed a dual-frequency chip or they are next to, what is still not completely clear is the main benefit of adding the second frequency. Is it beneficial just for correcting ionospheric error? Is it going to provide an improvement of the ranging error thanks to the wideband nature of the signal broadcast on the second frequency and their multipath rejection capabilities? Is it improving the measurement quality by means of a higher transmitting power? Could it be exploited as a source of data for the provision of accurate orbit and clocks corrections? What is the best PVT algorithm to apply to a multi-constellation dual-frequency mass-market chip? In order to answer to these questions, in the frame of the cooperation activities between ESA, GSA and chipset manufacturers to promote the use of Galileo, an evaluation kit of the Broadcom chip BCM4775 has been tested as it is the first dual frequency massmarket chip commercially available.
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:	323 - 333
Cite this article:	Crosta, Paolo, Zoccarato, Paolo, Lucas, Rafael, De Pasquale, G., "Dual Frequency Mass-market Chips: Test Results and Ways to Optimize PVT Performance," Proceedings of the 31st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS+ 2018), Miami, Florida, September 2018, pp. 323-333. https://doi.org/10.33012/2018.15882
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