A statistical approach to estimate Global Navigation Satellite Systems (GNSS) receiver signal tracking performance in the presence of ionospheric scintillation

Sreeja Vadakke Veettil,Luca Spogli,Marcio Aquino,Claudio Cesaroni

doi:10.1051/swsc/2018037

Abstract

Ionospheric scintillation can seriously impair the Global Navigation Satellite Systems (GNSS) receiver signal tracking performance, thus affecting the required levels of availability, accuracy and integrity of positioning that supports modern day GNSS based applications. We present results from the research work carried out under the Horizon 2020 European Commission (EC) funded Ionospheric Prediction Service (IPS) project. The statistical models developed to estimate the standard deviation of the receiver Phase Locked Loop (PLL) tracking jitter on the Global Positioning System (GPS) L1 frequency as a function of scintillation levels are presented. The models were developed following the statistical approach of generalized linear modelling on data recorded by networks in operation at high and low latitudes during the years of 2012–2015. The developed models were validated using data from different stations over varying latitudes, which yielded promising results. In the case of mid-latitudes, as the occurrence of strong scintillation is absent, an attempt to develop a dedicated model proved fruitless and, therefore, the models developed for the high and low latitudes were tested for two mid-latitude stations. The developed statistical models can be used to generate receiver tracking jitter maps over a region, providing users with the expected tracking conditions. The approach followed for the development of these models for the GPS L1 frequency can be used as a blueprint for the development of similar models for other GNSS frequencies, which will be the subject of follow on research.

Highlights

The effect of the Earth’s ionospheric environment currently represents the single largest contributor to the Global Navigation Satellite System (GNSS) error budget and abnormal ionospheric conditions can impose serious degradation on GNSS system functionality, including integrity, accuracy and availability
The development of the statistical models following the approach of Generalized Linear Modelling (GLM) to estimate rPLL at high and low latitudes is described
Using the statistical test described in the previous section, the models developed for the high latitudes showed a dependence of rPLL on the phase scintillation index, ru as well as on the ROTrms

Summary

Introduction

The effect of the Earth’s ionospheric environment currently represents the single largest contributor to the Global Navigation Satellite System (GNSS) error budget and abnormal ionospheric conditions can impose serious degradation on GNSS system functionality, including integrity, accuracy and availability. The receiver PLL performance is usually evaluated in terms of the phase tracking error variance, which is observed to correlate well with the scintillation levels at both high and low latitudes (Sreeja et al, 2012; Aquino & Sreeja, 2013). Several efforts have been made to model the effects of scintillation on the Global Positioning System (GPS) receiver PLL performance These can be summarized as: (i) development of scintillation sensitive PLL tracking models (Conker et al, 2003; Moraes et al, 2014), (ii) evaluation of PLL performance using a GPS signal simulator (Morrissey et al, 2004) and (iii) observation of receiver performance during actual events of scintillation in locations of interest (Groves et al, 2000)

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Results

Conclusion