On the phase detrending to disentangle refraction and diffraction on GNSS signals: a case study over Antarctica

2021 ◽  
Author(s):  
Luca Spogli ◽  
Hossein Ghobadi ◽  
Antonio Cicone ◽  
Lucilla Alfonsi ◽  
Claudio Cesaroni ◽  
...  
Keyword(s):  
Single Case ◽  
Cutoff Frequency ◽  
Satellite System ◽  
Fine Tuning ◽  
Scintillation Index ◽  
Ionospheric Scintillation ◽  
Iterative Filtering ◽  
Global Navigation Satellite ◽  
Value Changes

<p>We investigate the reliability of the phase scintillation index determined by receiving Global Navigation Satellite System (GNSS) signals at ground in the high-latitudes. To the scope, we report about the capabilities of recently introduced detrending scheme based on the signal decomposition provided by the Fast Iterative Filtering (FIF) technique. This detrending scheme enables a fine tuning of the cutoff frequency for phase detrending used in the phase scintillation index definition, aimed at disentangling diffraction and refraction effects. On a single case study based on GPS and Galileo data taken by a GNSS Ionospheric Scintillation Monitor Receiver (ISMR) in Concordia Station (Antarctica), we show how the FIF-based detrending allows deriving adaptive cutoff frequencies, whose value changes minute-by-minute. They are found to range between 0.4 Hz and 1.2 Hz. This allows better accounting for diffractive effects in phase scintillation index calculation and also showing the limitations on the use of such index, being still widely used in the community, both to characterize the features of ionospheric irregularities and to adopt mitigation solutions.</p>

scholarly journals Role of the external drivers in the occurrence of low-latitude ionospheric scintillation revealed by multi-scale analysis

2019 ◽  
Vol 9 ◽  
pp. A35 ◽  
Author(s):  
Luca Spogli ◽  
Mirko Piersanti ◽  
Claudio Cesaroni ◽  
Massimo Materassi ◽  
Antonio Cicone ◽  
...  
Keyword(s):  
Global Navigation Satellite Systems ◽  
Scintillation Index ◽  
Ionospheric Scintillation ◽  
Satellite Systems ◽  
Multi Scale ◽  
Amplitude Scintillation ◽  
Frequency Components ◽  
Scale Properties ◽  
Iterative Filtering ◽  
Global Navigation Satellite

We analyze the amplitude scintillation on L-band signals over San Miguel de Tucumán (Argentina), focusing on the multi-scale variability and speculating on the possible relationship between forcing factors from the geospace and the ionospheric response. The site is nominally located below the expected position of the southern crest of the Equatorial Ionospheric Anomaly (EIA). For this scope, we concentrate on the period 1–31 March 2011, during which one minor and one moderate storm characterize the first half of the month, while generally quiet conditions of the geospace stand for the second half. By leveraging on the Adaptive Local Iterative Filtering (ALIF) signal decomposition technique, we investigate the multi-scale properties of Global Navigation Satellite Systems (GNSS) amplitude scintillation and helio-geophysical parameters, looking for possible cause-effect mechanisms relating the former to the latter. Namely, we identify resonant modes in the Akasofu (ε) parameter as likely related to the frequency components in the time evolution found for the amplitude scintillation index, hence modulating the scintillation itself.

scholarly journals Inventory of Locations of Old Mining Works Using LiDAR Data: A Case Study in Slovakia

2021 ◽  
Vol 13 (12) ◽  
pp. 6981
Author(s):  
Marcela Bindzarova Gergelova ◽  
Slavomir Labant ◽  
Jozef Mizak ◽  
Pavel Sustek ◽  
Lubomir Leicher
Keyword(s):  
Satellite System ◽  
Precise Determination ◽  
Lidar Data ◽  
Positional Accuracy ◽  
Current Form ◽  
Mining History ◽  
Mining Works ◽  
Gnss Measurements ◽  
Global Navigation Satellite

The concept of further sustainable development in the area of administration of the register of old mining works and recent mining works in Slovakia requires precise determination of the locations of the objects that constitute it. The objects in this register have their uniqueness linked with the history of mining in Slovakia. The state of positional accuracy in the registration of objects in its current form is unsatisfactory. Different database sources containing the locations of the old mining works are insufficient and show significant locational deviations. For this reason, it is necessary to precisely locate old mining works using modern measuring technologies. The most effective approach to solving this problem is the use of LiDAR data, which at the same time allow determining the position and above-ground shape of old mining works. Two localities with significant mining history were selected for this case study. Positional deviations in the location of old mining works among the selected data were determined from the register of old mining works in Slovakia, global navigation satellite system (GNSS) measurements, multidirectional hill-shading using LiDAR, and accessible data from the open street map. To compare the positions of identical old mining works from the selected database sources, we established differences in the coordinates (ΔX, ΔY) and calculated the positional deviations of the same objects. The average positional deviation in the total count of nineteen objects comparing documents, LiDAR data, and the register was 33.6 m. Comparing the locations of twelve old mining works between the LiDAR data and the open street map, the average positional deviation was 16.3 m. Between the data sources from GNSS and the registry of old mining works, the average positional deviation of four selected objects was 39.17 m.

scholarly journals HEIGHT DETERMINATION TECHNIQUES FOR THE NEXT NATIONAL HEIGHT SYSTEM OF FINLAND - A CASE STUDY

2015 ◽  
Vol 41 (4) ◽  
pp. 145-155
Author(s):  
Timo Saari ◽  
Markku Poutanen ◽  
Veikko Saaranen ◽  
Harri Kaartinen ◽  
Antero Kukko ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Pilot Project ◽  
Satellite System ◽  
Reference Station ◽  
Virtual Reference ◽  
Precise Levelling ◽  
Height Determination ◽  
Weak Points ◽  
Global Navigation Satellite

Precise levelling is known for its accuracy and reliability in height determination, but the process itself is slow, laborious and expensive. We have started a project to study methods for height determination that could decrease the creation time of national height systems without losing the accuracy and reliability that is needed for them. In the pilot project described here, we study some of the alternative techniques with a pilot field test where we compared them with the precise levelling. The purpose of the test is not to evaluate the mutual superiority or suitability of the techniques, but to establish the background for a larger test and to find strong and weak points of each technique. The techniques chosen for this study were precise levelling, Mobile Laser Scanning (MLS) and Global Navigation Satellite System (GNSS) levelling, which included static Global Positioning System (GPS) and Virtual Reference Station (VRS) measurements. This research highlighted the differences of the studied techniques and gave insights about the framework and procedure for the later experiments. The research will continue in a larger scale, where the suitability of the techniques regarding the height systems is to be determined.

scholarly journals Climatology of Ionospheric Amplitude Scintillation on GNSS Signals at South American Sector During Solar Cycle 24

2021 ◽  
Author(s):  
Eduardo Perez Macho ◽  
Emilia Correia ◽  
Luca Spogli ◽  
Marcio Tadeu de Assis Honorato Muella
Keyword(s):  
Solar Cycle ◽  
Geomagnetic Storms ◽  
Satellite System ◽  
Scintillation Index ◽  
Ionospheric Scintillation ◽  
South American ◽  
Amplitude Scintillation ◽  
Solar Cycle 24 ◽  
Cycle 24 ◽  
The Impact

Abstract Scintillations are caused by ionospheric irregularities and can affect the propagation of trans-ionospheric radio signals. One way to understand and predict the impact of such irregularities on Global Navigation Satellite System (GNSS) signals is through the climatological behavior of the ionospheric scintillation indexes during the different phases of a solar cycle. In this work, we investigate the amplitude scintillation index S4 during the full solar cycle 24 at South American (SA) sector, that is featured by the Ionospheric Anomaly (EIA) and by the South Atlantic Magnetic Anomaly (SAMA). We also investigate the daily variation of S4 and two case studies during geomagnetic storms. The results show a significant intensification of amplitude scintillations at northern and southern crest of EIA, especially during the southern hemisphere’s spring/summer seasons, with a higher increase during solar maximum, and after sunset. And particularly at the SAMA region, where the intensity of magnetic field lines is lower, the S4 fluctuations are much higher.

Leveraging Intelligent Compaction and Thermal Profiling Technologies to Improve Asphalt Pavement Construction Quality: A Case Study

2018 ◽  
Vol 2672 (26) ◽  
pp. 48-56 ◽  
Author(s):  
George K. Chang ◽  
Kiran Mohanraj ◽  
William A. Stone ◽  
Daniel J. Oesch ◽  
Victor (Lee) Gallivan
Keyword(s):  
Real Time ◽  
Satellite System ◽  
Material Transfer ◽  
Intelligent Compaction ◽  
Two Factors ◽  
Thermal Profiling ◽  
Compaction Control ◽  
Pavement Construction ◽  
Global Navigation Satellite

Intelligent compaction (IC) is an emerging technology with rollers equipped with global navigation satellite system (GNSS), an accelerometer-based measurement system, and an onboard color-coded display for real-time monitoring and compaction control. Paver-mounted thermal profiling (PMTP) is used to monitor asphalt surface temperatures behind a paver with a thermal scanner, and to track paver speeds, stops, and stop durations. Leveraging both IC and PMTP technologies allows for paving and compaction controls in real time, and for executing appropriate adjustments as needed. A case study is used to demonstrate the advantage of using both IC and PMTP over conventional operations. Postconstruction asphalt coring and tests, as well as pavement profile surveys were conducted to provide asphalt density data and pavement smoothness acceptance data for comparison and correlation analysis with IC and PMTP data. The data from 2 days of operations, one without the Material Transfer Vehicle (MTV) and another with the MTV, were analyzed and compared to illustrate the benefits of using IC, PMTP, and MTV for producing quality pavement products. Durability and smoothness are two key construction qualities for agencies and users of hot mix asphalt (HMA) pavements. These two factors also affect the long-term structural and functional pavement performance.

scholarly journals MONITORING OF IONOSPHERIC SCINTILLATION PHENOMENA USING SYNTHETIC APERTURE RADAR (SAR)

2018 ◽  
Vol IV-5 ◽  
pp. 331-337
Author(s):  
S. Mohanty ◽  
C. Carrano ◽  
G. Singh
Keyword(s):  
Satellite System ◽  
Synthetic Aperture ◽  
Ionospheric Scintillation ◽  
Electron Content ◽  
Data Sets ◽  
Low Frequencies ◽  
Total Electron ◽  
Gnss Receiver ◽  
Synthetic Aperture Radars ◽  
Global Navigation Satellite

<p><strong>Abstract.</strong> The applications of synthetic aperture radars (SAR) have increased manifold in the past decade, which includes numerous Earth observation applications such as agriculture, forestry, disaster monitoring cryospheric- and atmospheric- studies. Among them, the potential of SAR for ionospheric studies is gaining importance. The susceptibility of SAR to space weather dynamics, and ionosphere in particular, comes at low frequencies of L- and P-bands. This paper discusses one such scintillation event that was observed by L-band Advanced Land Observation Satellite (ALOS)-2 Phased Array L-type SAR (PALSAR) over southern India on March 23, 2015. The sensors also acquired data sets on four other days on which the ionosphere was quiet. Ionospheric parameter measurements of total electron content (TEC) and amplitude scintillation (S<sub>4</sub>) index from ground-based Global Navigation Satellite System (GNSS) receiver at Tirunelveli was used to establish the ionospheric conditions on the days of SAR acquisition as well as to corroborate the S<sub>4</sub> estimated from SAR. Multi-temporal ALOS-2 data sets were utilized to calculate S<sub>4</sub> from two separate methods and the results have a good agreement with GNSS receiver measurements. This highlights the potential of SAR as an alternate technique of monitoring ionospheric scintillations that can be utilized as complementary to the highly accurate and dedicated measurements from the GNSS networks.</p>

scholarly journals Low-latitude scintillation occurrences around the equatorial anomaly crest over Indonesia

2014 ◽  
Vol 32 (1) ◽  
pp. 7-17 ◽  
Author(s):  
P. Abadi ◽  
S. Saito ◽  
W. Srigutomo
Keyword(s):  
Satellite System ◽  
Ionospheric Scintillation ◽  
Plasma Bubble ◽  
Equatorial Anomaly ◽  
Low Latitude ◽  
Magnetic Latitude ◽  
Background Density ◽  
Latitude Region ◽  
Global Navigation Satellite ◽  
First Time

Abstract. We investigated low-latitude ionospheric scintillation in Indonesia using two GPS receivers installed at Bandung (107.6° E, 6.9° S; magnetic latitude 17.5° S) and Pontianak (109.3° E, 0.02° S; magnetic latitude 8.9° S). This study aimed to characterise climatological and directional ionospheric scintillation occurrences, which are useful not only for the physics of ionospheric irregularities but also for practical use in GNSS (global navigation satellite system)-based navigation. We used the deployed instrument's amplitude scintillation (S4 index) data from 2009, 2010, and 2011; the yearly SSN (sunspot-smoothed numbers) were 3.1, 16.5, and 55.9, respectively. In summary, (1) scintillation occurrences in the post-sunset period (18:00–01:00 LT) during equinox months (plasma bubble season) at the two sites can be ascribed to the plasma bubble; (2) using directional analyses of the two sites, we found that the distribution of scintillation occurrences is generally concentrated between the two sites, indicating the average location of the EIA (equatorial ionisation anomaly) crest; (3) scintillation occurrence enhancements for the two sites in field-aligned directions are herein reported for the first time by ground-based observation in a low-latitude region; (4) distribution of scintillation occurrences at Pontianak are concentrated in the southern sky, especially in the southwest direction, which is very likely associated with the plasma bubble tilted westward with increasing latitude; and (5) scintillation occurrence in the post-midnight period in the non-plasma-bubble season is the most intriguing variable occurring between the two sites (i.e. post-midnight scintillations are observed more at Bandung than Pontianak). Most of the post-midnight scintillations observed at Bandung are concentrated in the northern sky, with low elevation angles. This might be due to the amplitude of irregularities in certain directions, which may be effectively enhanced by background density enhancement by the EIA and because satellite–receiver paths are longer in the EIA crest region and in a field-aligned direction.

scholarly journals A Study of the HWRF Analysis and Forecast Impact of Realistically Simulated CYGNSS Observations Assimilated as Scalar Wind Speeds and as VAM Wind Vectors

2018 ◽  
Vol 146 (7) ◽  
pp. 2221-2236 ◽  
Author(s):  
Bachir Annane ◽  
Brian McNoldy ◽  
S. Mark Leidner ◽  
Ross Hoffman ◽  
Robert Atlas ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Satellite System ◽  
Analysis Method ◽  
Short Term ◽  
Background Error ◽  
Wind Speeds ◽  
Ocean Surface Winds ◽  
Global Navigation Satellite ◽  
Data Assimilation System

Abstract In preparation for the launch of the NASA Cyclone Global Navigation Satellite System (CYGNSS), a variety of observing system simulation experiments (OSSEs) were conducted to develop, tune, and assess methods of assimilating these novel observations of ocean surface winds. From a highly detailed and realistic hurricane nature run (NR), CYGNSS winds were simulated with error characteristics that are expected to occur in reality. The OSSE system makes use of NOAA’s HWRF Model and GSI data assimilation system in a configuration that was operational in 2012. CYGNSS winds were assimilated as scalar wind speeds and as wind vectors determined by a variational analysis method (VAM). Both forms of wind information had positive impacts on the short-term HWRF forecasts, as shown by key storm and domain metrics. Data assimilation cycle intervals of 1, 3, and 6 h were tested, and the 3-h impacts were consistently best. One-day forecasts from CYGNSS VAM vector winds were the most dynamically consistent with the NR. The OSSEs have a number of limitations; the most noteworthy is that this is a case study, and static background error covariances were used.

scholarly journals Comparison of Two Approaches to GNSS Positioning Using Code Pseudoranges Generated by Smartphone Device

2021 ◽  
Vol 11 (11) ◽  
pp. 4787
Author(s):  
Massimiliano Pepe ◽  
Domenica Costantino ◽  
Gabriele Vozza ◽  
Vincenzo Saverio Alfio
Keyword(s):  
Mobile Devices ◽  
Single Point ◽  
Satellite System ◽  
Navigation Satellite ◽  
Gnss Positioning ◽  
Gis Applications ◽  
Accuracy And Precision ◽  
Global Navigation Satellite

The release of Android 7.0 has made raw GNSS positioning data available on smartphones and, as a result, this has allowed many experiments to be developed to evaluate the quality of GNSS positioning using mobile devices. This paper investigates the best positioning, using pseudorange measurement in the Differential Global Navigation Satellite System (DGNSS) and Single Point Positioning (SPP), obtained by smartphones. The experimental results show that SPP can be comparable to the DGNSS solution and can generally achieve an accuracy of one meter in planimetric positioning; in some conditions, an accuracy of less than one meter was achieved in the Easting coordinate. As far as altimetric positioning is concerned, it has been demonstrated that DGNSS is largely preferable to SPP. The aim of the research is to introduce a statistical method to evaluate the accuracy and precision of smartphone positioning that can be applied to any device since it is based only on the pseudoranges of the code. In order to improve the accuracy of positioning from mobile devices, two methods (Tukey and K-means) were used and applied, as they can detect and eliminate outliers in the data. Finally, the paper shows a case study on how the implementation of SPP on GIS applications for smartphones could improve citizen science experiments.

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