GNSS Data Processing and Analysis for Earthquake Disaster Prevention Monitoring

2018 ◽  
Vol 9 (2) ◽  
pp. 47-62
Author(s):  
Joon Kyu Park ◽  
Min Gyu Kim
Keyword(s):  
Precise Point Positioning ◽  
Reference Station ◽  
Relative Positioning ◽  
Monitoring Methods ◽  
National Geographic ◽  
Seismological Observation ◽  
Richter Scale ◽  
Earthquake Observation ◽  
Location Change ◽  
Gnss Data

This article describes how an earthquake with highest magnitude 5.8 on the Richter scale occurred in the Gyeongju area on Sep. 12, 2016 since the first seismological observation. In addition, continuous aftershocks have occurred. There is a pressing need for proper earthquake monitoring and prevention systems. This article is intended to apprehend the dislocation and location change of Continuously Operating Reference Station (CORS) caused by earthquake by means of data on CORS of the National Geographic Information Institute (NGII) and suggest effective seismic monitoring methods. Through Precise Point Positioning (PPP) over earthquake occurrence locations, it was possible to determine the dislocation aspects of CORS for TEGN and CHSG near the seismic epicenter. The nationwide Relative Positioning processing of data for 58 CORS from Sep. 1 to Sep. 30 suggested that CORS had not transitioned coordinates due to the earthquake. For the sake of more efficient earthquake observation and monitoring, it is believed that highly frequent GNSS data acquisition and the additional installation of observation devices such as seismometers is required.

Comparison between multi-constellation ambiguity-fixed PPP and RTK for maritime precise navigation

2015 ◽  
Vol 9 (2) ◽  
Author(s):  
Javier Tegedor ◽  
Xianglin Liu ◽  
Ole Ørpen ◽  
Niels Treffers ◽  
Matthew Goode ◽  
...  
Keyword(s):  
Performance Assessment ◽  
Real Time ◽  
Carrier Phase ◽  
Precise Point Positioning ◽  
High Accuracy ◽  
Reference Station ◽  
Satellite Systems ◽  
Real Time Kinematic ◽  
Gnss Data ◽  
Long Baselines

AbstractIn order to achieve high-accuracy positioning, either Real-Time Kinematic (RTK) or Precise Point Positioning (PPP) techniques can be used. While RTK normally delivers higher accuracy with shorter convergence times, PPP has been an attractive technology for maritime applications, as it delivers uniform positioning performance without the direct need of a nearby reference station. Traditional PPP has been based on ambiguity-­float solutions using GPS and Glonass constellations. However, the addition of new satellite systems, such as Galileo and BeiDou, and the possibility of fixing integer carrier-phase ambiguities (PPP-AR) allow to increase PPP accuracy. In this article, a performance assessment has been done between RTK, PPP and PPP-AR, using GNSS data collected from two antennas installed on a ferry navigating in Oslo (Norway). RTK solutions have been generated using short, medium and long baselines (up to 290 km). For the generation of PPP-AR solutions, Uncalibrated Hardware Delays (UHDs) for GPS, Galileo and BeiDou have been estimated using reference stations in Oslo and Onsala. The performance of RTK and multi-­constellation PPP and PPP-AR are presented.

scholarly journals Experimental estimation of GNSS performances at the national aviation university

2020 ◽  
Vol 164 ◽  
pp. 03052
Author(s):  
Volodymir Kharchenko ◽  
Valeriy Konin ◽  
Olexiy Pogurelsky ◽  
Ekaterina Stativa
Keyword(s):  
Experimental Data ◽  
Continuous Monitoring ◽  
Goal Achievement ◽  
Global Navigation Satellite Systems ◽  
Reference Station ◽  
Satellite Systems ◽  
Systems Quality ◽  
Primary Focus ◽  
Global Navigation Satellite ◽  
Gnss Data

The goal of the research is to develop a of Global Navigation Satellite Systems quality monitoring methodology based on available equipment in the satellite navigation laboratory of the National Aviation University (Kyiv, Ukraine). For successful the goal achievement it is necessary to solve follow list of tasks: to determine the composition of the necessary equipment and order of it installing and connection; to develop the necessary software for processing received GNSS data; to estimate the GNSS characteristics with the help of experimental data. The primary focus of this research is on the following characteristics: accuracy (in terms of deviation coordinates in horizontal and vertical planes from the coordinates of the reference station and numerical values in meters); integrity information (summarized in the form of horizontal and Stanford plots); overall availability of service – measured as the availability of signals meeting the requirements for instrumented approaches with vertical guidance (APV) APV-1, APV-2, and Category 1 (CAT-1) precision approaches to runways. The main result of this research is developing software that could be applied for continuous monitoring of GNSS performances. The possibilities of it were successfully tested with the help of experimental data received from GPS and Galileo satellites.

scholarly journals Wave measurements with a modified HydroBall® buoy using different GNSS processing strategies

GEOMATICA ◽  
2019 ◽  
Vol 73 (1) ◽  
pp. 1-14
Author(s):  
Benoit Crépeau Gendron ◽  
Mohamed Ali Chouaer ◽  
Rock Santerre ◽  
Mathieu Rondeau ◽  
Nicolas Seube
Keyword(s):  
Precise Point Positioning ◽  
Reference Station ◽  
Controlled Environment ◽  
Wave Measurements ◽  
Wave Measurement ◽  
Processing Strategies ◽  
Wave Heights ◽  
Kinematic Ppp ◽  
Gnss Processing

One of the CIDCO’s (The Interdisciplinary Center for the Development of Ocean Mapping) HydroBall® GNSS buoys has been specifically adapted to evaluate its potential for wave measurement at centimeter accuracy level. Multiple GNSS processing strategies were tested, namely PPK (Post-Processed Kinematic), PPP (Precise Point Positioning), and TRP (Time Relative Positioning). Experiments were carried out in a hydraulic flume where waves of different amplitudes and periods were generated in a controlled environment. The wave heights obtained by the various GNSS solutions were compared with ultrasonic gauge measurements placed along the flume. The best results were obtained with the PPK and TRP solutions with root mean squared (RMS) values of 2 cm (on average). The main advantages of the TRP solution are that it does not require any reference station nearby (contrary to PPK) or precise ephemerides (required by PPP). A sinusoidal regression comparison of the wave height time series allowed determination of the wave period and amplitude with mean errors of 0.06 s and 0.8 cm, respectively.

scholarly journals REVISITING THE ROLE OF OBSERVATION SESSION DURATION ON PRECISE POINT POSITIONING ACCURACY USING GIPSY/OASIS II SOFTWARE

2016 ◽  
Vol 22 (3) ◽  
pp. 405-419 ◽  
Author(s):  
Adem G. Hayal ◽  
D. Ugur Sanli
Keyword(s):  
Precise Point Positioning ◽  
Accuracy Assessment ◽  
Relative Positioning ◽  
International Gnss Service ◽  
Session Duration ◽  
Previous Formulation ◽  
Single Station ◽  
Analysis Strategies ◽  
Point Positioning

The accuracy of GPS precise point positioning (PPP) was previously modelled as a function of the observing session duration T. The NASA, JPL's software GIPSY OASIS II (GOA-II) along with the legacy products was used to process the GPS data. The original accuracy model is not applicable anymore because JPL started releasing its products using new modelling and analysis strategies as of August 2007, and the legacy products are no longer available. The developments mainly comprise the new orbit and clock determination strategy, second order ionosphere modelling, and single station ambiguity resolution. Previously, the PPP accuracy was studied using v 4.0 of the GOA-II. The accuracy model showed coarser results compared to that of the relative positioning. Here, we processed the data of the International GNSS Service (IGS) stations to refine the accuracy of GOA-II PPP from version 6.3. Considering the above changes we refined the accuracy of PPP. First we modified the previous model used for the accuracy assessment. Then we tested out this model using straightforward polynomial and logarithmic models. The tests indicate the previous formulation still satisfactorily models the accuracy using refined coefficient values Sn = 7.8 mm , Se = 6.8 mm , Sv = 29.9 mm for T ≥ 2 h.

scholarly journals Subsidence determination in the Central Valley, California

2018 ◽  
Vol 106 (1) ◽  
pp. 35-42 ◽  
Author(s):  
Marcelo Romero ◽  
Mike Mustafa Berber
Keyword(s):  
Central Valley ◽  
Satellite System ◽  
Geodetic Survey ◽  
Reference Station ◽  
National Geodetic Survey ◽  
The North ◽  
Elevation Changes ◽  
System Data ◽  
Global Navigation Satellite ◽  
Gnss Data

Abstract Twenty four hour GNSS (Global Navigation Satellite System) data acquired monthly for 5 years from 8 CORS (Continuously Operating Reference Station) stations in Central Valley, California are processed and vertical velocities of the points are determined. To process GNSS data, online GNSS data processing service APPS (Automatic Precise Positioning Service) is used. GNSS data downloaded from NGS (National Geodetic Survey) CORS are analyzed and subsidence at these points is portrayed with graphics. It is revealed that elevation changes range from 5 mm uplift in the north to 163 mm subsidence in the southern part of the valley.

scholarly journals Posicionamento GNSS em Tempo Real: Evolução, Aplicações Práticas e Perspectivas para o Futuro

2020 ◽  
Vol 72 ◽  
pp. 1359-1379
Author(s):  
Claudia Pereira Krueger ◽  
Paulo Sérgio de Oliveira Junior ◽  
Silvio Jacks dos Anjos Garnés ◽  
Daniele Barroca Marra Alves ◽  
Jorge Felipe Euriques
Keyword(s):  
Real Time ◽  
Global Positioning System ◽  
Precise Point Positioning ◽  
Reference Station ◽  
Space Representation ◽  
Positioning System ◽  
Differential Gps ◽  
Virtual Reference ◽  
State Space Representation ◽  
Global Positioning

O posicionamento em tempo real por meio do emprego dos sinais de satélites foi um avanço nas navegações aérea, marítima e terrestre com o surgimento do GPS (Global Positioning System). Contudo as precisões horizontais e verticais de 100 m e 150 m (nível de probabilidade de 95%) alcançadas, estando a SA (Selective Availability) ativada, passaram a não ser satisfatórias para muitas aplicações e os usuários buscaram galgar outros níveis de precisões. Esforços foram investidos no chamado posicionamento diferencial DGPS (Differential GPS), o qual possibilitou obter precisões em torno de dez vezes melhores do que as do posicionamento absoluto.  Posteriormente, usando-se a fase da onda portadora, conseguiu-se realizar posicionamento com maior acurácia por meio do método RTK (Real Time Kinematic), atingindo qualidade centimétrica. Na sequência, houve uma evolução para posicionamentos em rede, empregando, por exemplo, o algoritmo de VRS (Virtual Reference Station). Vários erros nas observáveis dos satélites passaram a ser modelados com uma solução de multiestações em tempo real. A partir de 2012, surgiram serviços e produtos que favoreceram o desenvolvimento do RT-PPP (Real-Time Precise Point Positioning) baseado no conceito SSR (State Space Representation). A busca da solução das ambiguidades no RT-PPP deu origem ao PPP-RTK com menor tempo de fixação das ambiguidades e convergência para a solução acurada do posicionamento. Neste artigo apresenta-se como foi a evolução do posicionamento em tempo real, algumas das aplicações no âmbito nacional e as perspectivas  desta modalidade de posicionamento para o futuro.

scholarly journals GNSS-based water vapor estimation and validation during the MOSAiC expedition

2021 ◽  
Author(s):  
Benjamin Männel ◽  
Florian Zus ◽  
Galina Dick ◽  
Susanne Glaser ◽  
Maximilian Semmling ◽  
...  
Keyword(s):  
Water Vapor ◽  
Very Long Baseline Interferometry ◽  
Precise Point Positioning ◽  
Radiosonde Data ◽  
Weather Data ◽  
Radio Telescopes ◽  
Long Baseline ◽  
Gnss Data ◽  
Level Of Agreement ◽  
Good Agreement

Abstract. Within the transpolar drifting expedition MOSAiC (Multidisciplinary drifting Observatory for the Study of Arctic Climate), GNSS was used among other techniques to monitor variations in atmospheric water vapor. Based on 15 months of continuously tracked GNSS data including GPS, GLONASS, and Galileo, epoch-wise coordinates and hourly zenith total delays (ZTD) were determined using a kinematic precise point positioning (PPP) approach. The derived ZTD values agree to 1.1 ± 0.2 mm (RMS of the differences 10.2 mm) with the numerical weather data of ECMWF’s latest reanalysis, ERA5, computed for the derived ship’s locations. This level of agreement is also confirmed by comparing the on-board estimates with ZTDs derived for terrestrial GNSS stations in Bremerhaven and Ny Ålesund and for the radio telescopes observing Very Long Baseline Interferometry in Ny Ålesund. Preliminary estimates of integrated water vapor derived from frequently launched radiosondes are used to assess the GNSS-derived integrated water vapor estimates. The overall difference of 0.08 ± 0.04 kg m−2 (RMS of the differences 1.47 kg m−2) demonstrates a good agreement between GNSS and radiosonde data. Finally, the water vapor variations associated with two warm air intrusion events in April 2020 are assessed.

scholarly journals An improved pixel-based water vapor tomography model

2019 ◽  
Vol 37 (1) ◽  
pp. 89-100
Author(s):  
Yibin Yao ◽  
Linyang Xin ◽  
Qingzhi Zhao
Keyword(s):  
Water Vapor ◽  
Three Dimensional ◽  
Satellite System ◽  
Reference Station ◽  
Weather Forecasts ◽  
Satellite Positioning ◽  
Optimal Polynomial ◽  
Improved Model ◽  
Global Navigation Satellite ◽  
Gnss Data

Abstract. As an innovative use of Global Navigation Satellite System (GNSS), the GNSS water vapor tomography technique shows great potential in monitoring three-dimensional water vapor variation. Most of the previous studies employ the pixel-based method, i.e., dividing the troposphere space into finite voxels and considering water vapor in each voxel as constant. However, this method cannot reflect the variations in voxels and breaks the continuity of the troposphere. Moreover, in the pixel-based method, each voxel needs a parameter to represent the water vapor density, which means that huge numbers of parameters are needed to represent the water vapor field when the interested area is large and/or the expected resolution is high. In order to overcome the abovementioned problems, in this study, we propose an improved pixel-based water vapor tomography model, which uses layered optimal polynomial functions obtained from the European Centre for Medium-Range Weather Forecasts (ECMWF) by adaptive training for water vapor retrieval. Tomography experiments were carried out using the GNSS data collected from the Hong Kong Satellite Positioning Reference Station Network (SatRef) from 25 March to 25 April 2014 under different scenarios. The tomographic results are compared to the ECMWF data and validated by the radiosonde. Results show that the new model outperforms the traditional one by reducing the root-mean-square error (RMSE), and this improvement is more pronounced, at 5.88 % in voxels without the penetration of GNSS rays. The improved model also has advantages in more convenient expression.

Determining the Coordinates of Control Points in Hydrographic Surveying by the Precise Point Positioning Method

2017 ◽  
Vol 70 (6) ◽  
pp. 1241-1252
Author(s):  
Burak Akpınar ◽  
Nedim Onur Aykut
Keyword(s):  
Precise Point Positioning ◽  
Global Navigation Satellite Systems ◽  
Reference Station ◽  
Control Points ◽  
Dual Frequency ◽  
Satellite Systems ◽  
Positioning Method ◽  
Test Points ◽  
Point Positioning ◽  
Hydrographic Surveying

After Global Navigation Satellite Systems (GNSS) were first used in the field of hydrography in 1980, developments in hydrographic surveying accelerated. Survey precision in hydrography has been improved for both horizontal and vertical positioning and seafloor acoustic measurement by means of these new developments. Differential Global Positioning System (DGPS), Real Time Kinematic (RTK) and Network RTK (NRTK) techniques are the satellite-based positioning techniques that are commonly used in shallow water surveys and shoreline measurements. In line with these developments, the newer Precise Point Positioning (PPP) has been introduced. Combining precise satellite positions and clocks with dual-frequency GNSS data, PPP can provide position solutions from the centimetre to decimetre level. In this study, the coordinates of control points were determined by using the Post-Process PPP (PP-PPP) technique. Seven test points, which are the points of the Continuously Operating Reference Station - Turkey (CORS-TR) network, are selected near the shorelines within Turkey. The 24-hour data was split from one to six hours by one hour periods. Automatic Point Positioning Service (APPS) was selected to process the data. The poisoning error of the test points were given and compared with International Hydrographic Organization (IHO) S44 hydrographic survey standards.

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