scholarly journals SNR-Based GNSS-R for Coastal Sea-Level Altimetry

Geosciences ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 391
Author(s):  
Sajad Tabibi ◽  
Renaldo Sauveur ◽  
Kelly Guerrier ◽  
Gerard Metayer ◽  
Olivier Francis
Keyword(s):  
Sea Level ◽  
Reference Frame ◽  
Global Navigation Satellite System ◽  
Satellite System ◽  
Terrestrial Reference Frame ◽  
Coast Guard ◽  
Navigation Satellite ◽  
Sea Levels ◽  
Global Navigation ◽  
Global Navigation Satellite

Geodetic Global Navigation Satellite System reflectometry (GNSS-R) uses ground-based signals of opportunity to retrieve sea levels at an intermediate spatial scale. Geodetic GNSS-R is based on the simultaneous reception of Line-of-Sight (LoS) and its coherent GNSS sea surface reflection (non-LOS) signals. The scope of this paper is to present geodetic GNSS-R applied to sea level altimetry. Signal-to-Noise Ratio (SNR) measurements from a Commercial Off-The-Shelf (COTS) geodetic-quality GNSS station at the Haiti Coast Guard Base in Port-au-Prince is used to retrieve sea levels in the International Terrestrial Reference Frame 2014 (ITRF2014). The GNSS-R sea levels are compared with those of the OTT Radar Level Sensor (RLS) installed vertically below the GNSS antenna. The Root-Mean-Square Error (RMSE) between the geodetic GNSS-R sea levels and OTT RLS records is 3.43 cm, with a correlation of 0.96. In addition, the complex differences between the OTT RLS records and 15-min GNSS-R sea levels using Global Positioning System (GPS) and Globalnaya Navigazionnaya Sputnikovaya Sistema (or Global Navigation Satellite System; GLONASS) signals for all the eight major tidal constituents are in mm-level agreement. Therefore, geodetic GNSS-R can be used as a complementary approach to the conventional method for sea level studies in a stable terrestrial reference frame.

scholarly journals Tracking of geodetic height of sea level in the west of Java Sea, Indonesia: A preliminary assessment

2019 ◽  
Vol 94 ◽  
pp. 01003 ◽  
Author(s):  
Poerbandono ◽  
Kosasih Prijatna ◽  
Irwan Gumilar
Keyword(s):  
Sea Level ◽  
Global Navigation Satellite System ◽  
Satellite System ◽  
Careful Examination ◽  
Navigation Satellite ◽  
The West ◽  
Geodetic Height ◽  
Java Sea ◽  
Global Navigation ◽  
Global Navigation Satellite

This paper assesses the agreement between observed heights of sea level from Global Navigation Satellite System (GNSS) and a global model of Mean Sea Surface (MSS). The assessment of the agreement is carried out according to the direct comparison between the height of MSS model and the geodetic height of actual sea level. Here, MSS is generated according to Gravity Recovery And Climate Experiment (GRACE) Gravity Model (GGM) and Mean Dynamic Ocean Topography (MDOT). The tracking of geodetic heights of actual sea level are done by Wide Area Differential (WA D) and Real Time Precise Point Positioning (RTPPP) Global Navigation Satellite System (GNSS) along an approximately 180 Nm SW-NE transect of away-return ship track in the west of the Java Sea, Indonesia. It is found that the overall agreement between geodetic height of sea level and MSS observed by WA DGNSS is 7.5 cm (away tracking), while those observed by RTPPP GNSS is 39.5 cm (away tracking) and 36.0 cm (return tracking). This work recommends selection of the best-fit tide model and careful examination on the dynamics of antenna offset due to vessel attitude.

scholarly journals Estimativas do Nível do Mar na América do Sul a partir de Registros Maregráficos e Coordenadas SIRGAS-CON

2020 ◽  
Vol 72 (1) ◽  
pp. 142-158
Author(s):  
Lucas Gonzales Lima Pereira Calado ◽  
Silvio Jacks dos Anjos Garnés ◽  
Karoline Paes Jamur
Keyword(s):  
Sea Level ◽  
Global Navigation Satellite System ◽  
Satellite System ◽  
Navigation Satellite ◽  
Mean Sea Level ◽  
Global Navigation ◽  
Global Navigation Satellite

Neste estudo, avaliou-se a taxa relativa do nível do mar em 20 estações maregráficas, com dados mensais do Permanet Service for Mean Sea Level (PSMSL), na América do Sul. Para a estimativa do movimento vertical crustal foram utilizadas 12 estações do Global Navigation Satellite System (GNSS) da rede de monitoramento contínuo do Sistema de Referência Geocêntrico para as Américas (SIRGAS-CON), que ficam nas proximidades do marégrafo a uma distância máxima de 10km. Com o conhecimento da variação vertical, foi possível obter a taxa absoluta do nível do mar para 12 estações maregráficas. A análise estatística se procedeu pela regressão linear (linha de tendência) e regressão polinomial quadrática (aceleração). Assim, na América do Sul, a taxa de variação média do nível absoluto do mar resultou em 0,98 mm/ano ± 0,93 mm/ano, para um período médio de 1950 a 2018.

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.

Implementation of a Dual-Frequency GLONASS and GPS L1 C/A Software Receiver

2010 ◽  
Vol 63 (2) ◽  
pp. 269-287 ◽  
Author(s):  
S. Abbasian Nik ◽  
M. G. Petovello
Keyword(s):  
Global Navigation Satellite System ◽  
Critical Role ◽  
Satellite System ◽  
Navigation Satellite ◽  
Dual Frequency ◽  
Software Receiver ◽  
The Public ◽  
Global Navigation ◽  
Global Navigation Satellite

These days, Global Navigation Satellite System (GNSS) technology plays a critical role in positioning and navigation applications. Use of GNSS is becoming more of a need to the public. Therefore, much effort is needed to make the civilian part of the system more accurate, reliable and available, especially for the safety-of-life purposes. With the recent revitalization of Russian Global Navigation Satellite System (GLONASS), with a constellation of 20 satellites in August 2009 and the promise of 24 satellites by 2010, it is worthwhile concentrating on the GLONASS system as a method of GPS augmentation to achieve more reliable and accurate navigation solutions.

scholarly journals Computation Approach for Quantitative Dielectric Constant from Time Sequential Data Observed by CYGNSS Satellites

2021 ◽  
Vol 13 (11) ◽  
pp. 2032
Author(s):  
Junchan Lee ◽  
Sunil Bisnath ◽  
Regina S.K. Lee ◽  
Narin Gavili Kilane
Keyword(s):  
Dielectric Constant ◽  
Soil Moisture ◽  
Global Navigation Satellite System ◽  
Measurement Data ◽  
Satellite System ◽  
Computation Method ◽  
Navigation Satellite ◽  
Local Soil ◽  
Global Navigation ◽  
Global Navigation Satellite

This paper describes a computation method for obtaining dielectric constant using Global Navigation Satellite System reflectometry (GNSS-R) products. Dielectric constant is a crucial component in the soil moisture retrieval process using reflected GNSS signals. The reflectivity for circular polarized signals is combined with the dielectric constant equation that is used for radiometer observations. Data from the Cyclone Global Navigation Satellite System (CYGNSS) mission, an eight-nanosatellite constellation for GNSS-R, are used for computing dielectric constant. Data from the Soil Moisture Active Passive (SMAP) mission are used to measure the soil moisture through its radiometer, and they are considered as a reference to confirm the accuracy of the new dielectric constant calculation method. The analyzed locations have been chosen that correspond to sites used for the calibration and validation of the SMAP soil moisture product using in-situ measurement data. The retrieved results, especially in the case of a specular point around Yanco, Australia, show that the estimated results track closely to the soil moisture results, and the Root Mean Square Error (RMSE) in the estimated dielectric constant is approximately 5.73. Similar results can be obtained when the specular point is located near the Texas Soil Moisture Network (TxSON), USA. These results indicate that the analysis procedure is well-defined, and it lays the foundation for obtaining quantitative soil moisture content using the GNSS reflectometry results. Future work will include applying the computation product to determine the characteristics that will allow for the separation of coherent and incoherent signals in delay Doppler maps, as well as to develop local soil moisture models.

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