scholarly journals Ionospheric Remote Sensing with GNSS

Encyclopedia ◽  
2021 ◽  
Vol 1 (4) ◽  
pp. 1246-1256
Author(s):  
YuXiang Peng ◽  
Wayne A. Scales
Keyword(s):  
Remote Sensing ◽  
Global Navigation Satellite System ◽  
Charged Particles ◽  
Satellite System ◽  
Upper Atmosphere ◽  
Pivotal Role ◽  
Navigation Satellite ◽  
Plasma Medium ◽  
Physical Processes ◽  
Global Navigation Satellite

The Global Navigation Satellite System (GNSS) plays a pivotal role in our modern positioning, navigation and timing (PNT) technologies. GNSS satellites fly at altitudes of approximately 20,000 km or higher. This altitude is above an ionized layer of the Earth’s upper atmosphere, the so called “ionosphere”. Before reaching a typical GNSS receiver on the ground, GNSS satellite signals penetrate through the Earth’s ionosphere. The ionosphere is a plasma medium consisting of free charged particles that can slow down, attenuate, refract, or scatter the GNSS signals. Ionospheric density structures (also known as irregularities) can cause GNSS signal scintillations (phase and intensity fluctuations). These ionospheric impacts on GNSS signals can be utilized to observe and study physical processes in the ionosphere and is referred to ionospheric remote sensing. This entry introduces some fundamentals of ionospheric remote sensing using GNSS.

scholarly journals Legal Review of the Liability Framework for Remote Sensing by Looking at the Global Navigation Satellite System (GNSS)

2019 ◽  
Vol 7 (2) ◽  
Author(s):  
Simin Asadzadeh Talei ◽  
Sepideh Bouzari ◽  
Sakineh Bagheri
Keyword(s):  
Remote Sensing ◽  
Global Navigation Satellite System ◽  
Civil Liability ◽  
Satellite System ◽  
Navigation Satellite ◽  
Legal Recognition ◽  
The Subject ◽  
Global Navigation ◽  
The Law ◽  
Global Navigation Satellite

Compensation for losses in the law is certain and the civil liability system is designed to respond to this need. Nowadays, it is necessary to check compensation in different fields, and specialists in each field are seeking data to recognize liability issues and even reduce the risk of liability in their work. The legal recognition of the subject is necessary because the field of remote sensing and mapping is one of the fields with many activists and plays an important role in various aspects of the life of the community, but many people still do not have any data about their rights, and even those involved in this field as producers or consumers does not have legal data on this issue, and due to the involvement of this data in the lives of individuals and the existence of relevant cases in the judiciary. Therefore, the accurate recognition of this issue will cause questions in this field to be answered in law. And lawyers and judges can also rely on the recognition and analysis of this issue to avoid error and work more efficiently.Key words: Liability, Remote Sensing, Fault, Global Navigation Satellite System (GNSS)

scholarly journals Recent Progress on Vegetation Remote Sensing Using Spaceborne GNSS-Reflectometry

2021 ◽  
Vol 13 (21) ◽  
pp. 4244
Author(s):  
Xuerui Wu ◽  
Peng Guo ◽  
Yueqiang Sun ◽  
Hong Liang ◽  
Xinggang Zhang ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Water Content ◽  
Global Navigation Satellite System ◽  
Satellite System ◽  
Weak Links ◽  
Navigation Satellite ◽  
Exploratory Research ◽  
Vegetation Monitoring ◽  
Global Navigation ◽  
Global Navigation Satellite

Vegetation is an important part of the terrestrial ecosystem and plays a vital role in the global carbon cycle. Traditional remote sensing methods have certain limitations in vegetation monitoring, and the development of GNSS-R (Global Navigation Satellite System-Reflectometry) technology provides a new and complimentary method. With the CYGNSS (Cyclone Global Navigation Satellite System) launch and the increased data acquisition, the use of spaceborne GNSS-R for vegetation monitoring has become a research hotspot. However, due to the complex characteristics of vegetation, its application in this field is still in the exploratory research stage. On the basis of reviewing the current research status, this paper points out the weak links of this technology in terms of polarization and observation geometry. Combined with the microwave vegetation scattering model, this paper analyzes the full polarization bistatic scattering characteristics of vegetation and points out the influence of vegetation parameters (density, water content, and vegetation diameters). The potential feasibility of polarization GNSS-R and future development trends of GNSS-R technology in quantitative retrieval (such as vegetation water content and biomass) are also discussed.

scholarly journals Evaluation of CYGNSS Observations for Flood Detection and Mapping during Sistan and Baluchestan Torrential Rain in 2020

Water ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 2047
Author(s):  
Mahmoud Rajabi ◽  
Hossein Nahavandchi ◽  
Mostafa Hoseini
Keyword(s):  
Remote Sensing ◽  
Global Navigation Satellite System ◽  
Satellite System ◽  
Navigation Satellite ◽  
Management Options ◽  
Torrential Rain ◽  
Global Navigation ◽  
Flood Detection ◽  
Global Navigation Satellite ◽  
Sistan And Baluchestan

Flood detection and produced maps play essential roles in policymaking, planning, and implementing flood management options. Remote sensing is commonly accepted as a maximum cost-effective technology to obtain detailed information over large areas of lands and oceans. We used remote sensing observations from Global Navigation Satellite System-Reflectometry (GNSS-R) to study the potential of this technique for the retrieval of flood maps over the regions affected by the recent flood in the southeastern part of Iran. The evaluation was made using spaceborne GNSS-R measurements over the Sistan and Baluchestan provinces during torrential rain in January 2020. This area has been at a high risk of flood in recent years and needs to be continuously monitored by means of timely observations. The main dataset was acquired from the level-1 data product of the Cyclone Global Navigation Satellite System (CYGNSS) spaceborne mission. The mission consisted of a constellation of eight microsatellites with GNSS-R sensors onboard to receive forward-scattered GNSS signals from the ocean and land. We first focused on data preparation and eliminating the outliers. Afterward, the reflectivity of the surface was calculated using the bistatic radar equations formula. The flooded areas were then detected based on the analysis of the derived reflectivity. Images from Moderate-Resolution Imaging Spectroradiometer (MODIS) were used for evaluation of the results. The analysis estimated the inundated area of approximately 19,644 km2 (including Jaz-Murian depression) to be affected by the flood in the south and middle parts of the Sistan and Baluchestan province. Although the main mission of CYGNSS was to measure the ocean wind speed in hurricanes and tropical cyclones, we showed the capability of detecting floods in the study area. The sensitivity of the spaceborne GNSS-R observations, together with the relatively short revisit time, highlight the potential of this technique to be used in flood detection. Future GNSS-R missions capable of collecting the reflected signals from all available multi-GNSS constellations would offer even more detailed information from the flood-affected areas.

scholarly journals Response to Variations in River Flowrate by a Spaceborne GNSS-R River Width Estimator

2019 ◽  
Vol 11 (20) ◽  
pp. 2450 ◽  
Author(s):  
April Warnock ◽  
Christopher Ruf
Keyword(s):  
Remote Sensing ◽  
Global Navigation Satellite System ◽  
Satellite System ◽  
Radar System ◽  
Bistatic Radar ◽  
Navigation Satellite ◽  
Navigation Systems ◽  
Highly Correlated ◽  
Global Navigation Satellite

In recent years, the use of Global Navigation Satellite System-Reflectometry (GNSS-R) for remote sensing of the Earth’s surface has gained momentum as a means to exploit existing spaceborne microwave navigation systems for science-related applications. Here, we explore the potential for using measurements made by a spaceborne GNSS-R bistatic radar system (CYGNSS) during river overpasses to estimate its width, and to use that width as a proxy for river flowrate. We present a case study utilizing CYGNSS data collected in the spring of 2019 during multiple overpasses of the Pascagoula River in southern Mississippi over a range of flowrates. Our results demonstrate that a measure of river width derived from CYGNSS is highly correlated with the observed flowrates. We show that an approximately monotonic relationship exists between river flowrate and a measure of river width which we define as the associated GNSS-R width (AGW). These results suggest the potential for GNSS-R systems to be utilized as a means to estimate river flowrates and widths from space.

scholarly journals Performance evaluation of multi-GNSSs navigation in super synchronous transfer orbit and geostationary earth orbit

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Tao Shi ◽  
Xuebin Zhuang ◽  
Liwei Xie
Keyword(s):  
Global Navigation Satellite System ◽  
Autonomous Navigation ◽  
Satellite System ◽  
Earth Orbit ◽  
Navigation Satellite ◽  
Geostationary Earth Orbit ◽  
Beidou Navigation Satellite System ◽  
Transfer Orbit ◽  
High Orbit ◽  
Global Navigation Satellite

AbstractThe autonomous navigation of the spacecrafts in High Elliptic Orbit (HEO), Geostationary Earth Orbit (GEO) and Geostationary Transfer Orbit (GTO) based on Global Navigation Satellite System (GNSS) are considered feasible in many studies. With the completion of BeiDou Navigation Satellite System with Global Coverage (BDS-3) in 2020, there are at least 130 satellites providing Position, Navigation, and Timing (PNT) services. In this paper, considering the latest CZ-5(Y3) launch scenario of Shijian-20 GEO spacecraft via Super-Synchronous Transfer Orbit (SSTO) in December 2019, the navigation performance based on the latest BeiDou Navigation Satellite System (BDS), Global Positioning System (GPS), Galileo Navigation Satellite System (Galileo) and GLObal NAvigation Satellite System (GLONASS) satellites in 2020 is evaluated, including the number of visible satellites, carrier to noise ratio, Doppler, and Position Dilution of Precision (PDOP). The simulation results show that the GEO/Inclined Geo-Synchronous Orbit (IGSO) navigation satellites of BDS-3 can effectively increase the number of visible satellites and improve the PDOP in the whole launch process of a typical GEO spacecraft, including SSTO and GEO, especially for the GEO spacecraft on the opposite side of Asia-Pacific region. The navigation performance of high orbit spacecrafts based on multi-GNSSs can be significantly improved by the employment of BDS-3. This provides a feasible solution for autonomous navigation of various high orbit spacecrafts, such as SSTO, MEO, GEO, and even Lunar Transfer Orbit (LTO) for the lunar exploration mission.

scholarly journals OutFin, a multi-device and multi-modal dataset for outdoor localization based on the fingerprinting approach

2021 ◽  
Vol 8 (1) ◽  
Author(s):  
Fahad Alhomayani ◽  
Mohammad H. Mahoor
Keyword(s):  
Global Navigation Satellite System ◽  
Urban Areas ◽  
Satellite System ◽  
Reference Points ◽  
Navigation Satellite ◽  
Data Types ◽  
Entry Barrier ◽  
Promising Alternative ◽  
Global Navigation ◽  
Global Navigation Satellite

AbstractIn recent years, fingerprint-based positioning has gained researchers’ attention since it is a promising alternative to the Global Navigation Satellite System and cellular network-based localization in urban areas. Despite this, the lack of publicly available datasets that researchers can use to develop, evaluate, and compare fingerprint-based positioning solutions constitutes a high entry barrier for studies. As an effort to overcome this barrier and foster new research efforts, this paper presents OutFin, a novel dataset of outdoor location fingerprints that were collected using two different smartphones. OutFin is comprised of diverse data types such as WiFi, Bluetooth, and cellular signal strengths, in addition to measurements from various sensors including the magnetometer, accelerometer, gyroscope, barometer, and ambient light sensor. The collection area spanned four dispersed sites with a total of 122 reference points. Each site is different in terms of its visibility to the Global Navigation Satellite System and reference points’ number, arrangement, and spacing. Before OutFin was made available to the public, several experiments were conducted to validate its technical quality.

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