Scintillations of the GPS, GLONASS, and Galileo signals at equatorial latitude

Abstract

Small scale ionospheric disturbances can lead to fluctuations of the received satellite signal, so-called signal scintillations. For global navigation satellite systems (GNSS) this reduces the positioning accuracy. Particular strong events can even lead to a loss of lock between satellite and receiver. All GNSS signals are affected by this phenomenon. The influence of the short scale disturbances on the different GNSS signals is expected to be different for each signal, since the signals are transmitted by different carrier frequencies and are constructed in different ways. In this paper, we compare the occurrence rate of signal scintillations between the different global navigation satellite systems and their different signal frequencies. In particular, we consider GPS L1, L2, and L5, GLONASS L1 and L2, and Galileo E1 and E5a. This analysis uses data from a high-rate GNSS station of the German Aerospace Center (DLR) placed in Bahir Dar, Ethiopia at 11°36 0 N 37°23 0 E. The station collects 50 Hz raw data from which the amplitude scintillation index S 4 is calculated. The data has been collected for the whole year 2013. Since the number of strong scintillation events with S 4 > 0.5 was smaller than expected, additionally weak scintillation events with S 4 ! 0.25 are taken into account. An algorithm is used that provides a soft barrier for S 4 ! 0.25. The resulting events are shown as daily and seasonal averages. Finally, the overall influence of short scale ionospheric disturbances in the form of signal scintillations on the GNSS signals is estimated.

Scintillation measurements at Bahir Dar during the high solar activity phase of solar cycle 24

“…As is well known (e.g. Basu and Basu, 1981;Aarons, 1982;Hlubek et al, 2014), signal scintillations could be observed in the evening hours after sunset.…”

“…Wiens et al, 2006). Using a single global navigation satellite system (GNSS) station, Hlubek et al (2014) have recently shown statistics of scintillation events occurring over the Bahir Dar region for GPS frequencies L1, L2C, and L5, GLONASS L1 and L2, and Galileo E1 and E5, covering the year 2013. These frequencies range between 1176.45 MHz (Galileo E5) and 1610.485 MHz (GLONASS L1).…”

A Method for Automatic Detection of Plasma Depletions by Using GNSS Measurements

“…The equatorial ionosphere with its complex dispersive features is of special interest in space weather research, which supports the operation of space‐based radio systems such as the Global Navigation Satellite System (GNSS) and remote sensing radars. The equatorial ionosphere is commonly characterized by the occurrence of enhanced GNSS signal scintillations in the evening hours (e.g., Hlubek et al, ; Kriegel et al, ). As has already been described many years ago, for example, by DasGupta et al (), the enhancement of amplitude scintillations is inherently associated with total electron content (TEC) depletions.…”

“…Recently, Blanch et al () improved the characterization and modeling of plasma depletion by modifying a previously developed technique for detecting medium‐scale traveling ionospheric disturbances (Hernández‐Pajares et al, ). Based on former scintillation studies by Hlubek et al () and Kriegel et al () at Bahir Dar, we present a new method of describing plasma depletions, which are often associated with GNSS signal scintillations. Here, we focus on describing a new plasma bubble detection algorithm and demonstrating its practical value for automatized bubble detection (and the corresponding statistical analysis).…”

An ionospheric index suitable for estimating the degree of ionospheric perturbations

“…Furthermore, the huge diversity of different structures within the ionosphere like plasma bubbles, patches, gradients Pradipta & Doherty (2016), traveling ionospheric disturbances (TIDs) (Borries et al, 2009) influence high frequency and trans-ionospheric radio wave propagation. So the associated impact causes amplitude and phase scintillation of GNSS signals Basu & Basu (1981), Béniguel et al (2009), Hlubek et al (2014), Kriegel et al (2017) and other ionospheric effects on space-based radar Xu et al (2004).…”