Title: GISMO: A Smart Sensor to Mitigate and Monitor Ionospheric Effects
Author(s): L. Siniscalco, N. Pastori, A. Zin, A. Emmanuele, A. Ferrario, C. Manno, B. Forte
Published in: Proceedings of the 30th International Technical Meeting of The Satellite Division of the Institute of Navigation (ION GNSS+ 2017)
September 25 - 29, 2017
Oregon Convention Center
Portland, Oregon
Pages: 2263 - 2272
Cite this article: Siniscalco, L., Pastori, N., Zin, A., Emmanuele, A., Ferrario, A., Manno, C., Forte, B., "GISMO: A Smart Sensor to Mitigate and Monitor Ionospheric Effects," Proceedings of the 30th International Technical Meeting of The Satellite Division of the Institute of Navigation (ION GNSS+ 2017), Portland, Oregon, September 2017, pp. 2263-2272.
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Abstract: Radio signals propagating through the Earth’s ionosphere can traverse inhomogeneities in the plasma density spatial distribution. These inhomogeneities can be associated with instabilities that originate a large-to-small scale energy cascade. When large-to-small irregularities drift across ray paths, radio signals are scattered and, as a consequence, a receiver will experience temporal fluctuations in the received intensity and phase of the signal. These fluctuations, known as scintillations, are responsible for signal fading and increased errors on the carrier phase estimates. Ionospheric scintillation is responsible for degradation and outages of services reliant upon satellite navigation and telecommunications. The low latitudes ionosphere is associated with the most disruptive scintillation due to strong scattering arising from propagation across ionospheric irregularities connected with plasma bubbles. In the presence of moderate-to-strong scintillation the probability of losses of lock increases, posing a barrier to safety-critical applications using satellite navigation (e.g. EGNOS and SBAS). The challenge during moderate-to-strong scintillation is to maintain high accuracy in the carrier phase estimate as well as to maintain lock. Such a challenge was tackled in the present work, where modifications to an existing GNSS multi-frequency multi-constellation receiver (i.e. GISMO) have been adopted to improve performance in the presence of moderate-to-strong scintillation typical of the low latitudes ionosphere. The modifications include a Kalmanfiltered version of the PLL together with an intelligent loss of lock detector that have been optimized through simulations first and then verified through an experimental campaign in Africa. The experimental data show encouraging results with a clear reduction in the losses of lock during moderate-to-strong scintillation together with unmodified accuracy in the carrier phase estimates. Future improvements along this line have been planned already.