scholarly journals Real-Time High-Rate GNSS Displacements: Performance Demonstration during the 2019 Ridgecrest, California, Earthquakes

2019 ◽  
Vol 91 (4) ◽  
pp. 1943-1951 ◽  
Author(s):  
Diego Melgar ◽  
Timothy I. Melbourne ◽  
Brendan W. Crowell ◽  
Jianghui Geng ◽  
Walter Szeliga ◽  
...  
Keyword(s):  
Real Time ◽  
Inertial Sensors ◽  
Global Navigation Satellite Systems ◽  
High Rate ◽  
Source Characterization ◽  
Satellite Systems ◽  
Earthquake Sources ◽  
Initial Source ◽  
Global Navigation Satellite ◽  
Good Agreement

Abstract Traditional real-time (RT) seismology has relied on inertial sensors to characterize ground motions and earthquake sources, particularly for hazards applications such as warning systems. In the past decade, a revolution in high-rate, RT Global Navigation Satellite Systems (GNSS) displacement has provided a new source of data to augment traditional measurement devices. The Ridgecrest, California, earthquake sequence in 2019 provided one of the most complete recordings of RT-GNSS displacements to date, helping aid in an initial source characterization over the first few days. In this article, we analyze and make available the archived RT displacement streams and compare their performance to postprocessed results, which we also provide. We find good agreement for all stations showing a noticeable signal. This demonstrates that simple modeling in RT, such as peak ground displacement scaling, would be practically identical to postprocessed results. Similarly, we find good agreement across the full spectral range, from the coseismic offsets (∼0  Hz) to the Nyquist frequency. We also find low latency between the measurement acquisition at the field site and the position calculation at the data center. In aggregate, the performance during the Ridgecrest earthquakes is strong evidence of the viability and usefulness of RT-GNSS as a monitoring tool.

scholarly journals CENTIMETER-LEVEL, ROBUST GNSS-AIDED INERTIAL POST-PROCESSING FOR MOBILE MAPPING WITHOUT LOCAL REFERENCE STATIONS

2016 ◽  
Vol XLI-B3 ◽  
pp. 819-826
Author(s):  
J. J. Hutton ◽  
N. Gopaul ◽  
X. Zhang ◽  
J. Wang ◽  
V. Menon ◽  
...  
Keyword(s):  
Inertial Sensors ◽  
Global Navigation Satellite Systems ◽  
Reference Station ◽  
Mobile Mapping ◽  
Satellite Systems ◽  
Local Reference ◽  
Set Up ◽  
Global Navigation Satellite ◽  
Airborne Mapping ◽  
Advanced Model

For almost two decades mobile mapping systems have done their georeferencing using Global Navigation Satellite Systems (GNSS) to measure position and inertial sensors to measure orientation. In order to achieve cm level position accuracy, a technique referred to as post-processed carrier phase differential GNSS (DGNSS) is used. For this technique to be effective the maximum distance to a single Reference Station should be no more than 20 km, and when using a network of Reference Stations the distance to the nearest station should no more than about 70 km. This need to set up local Reference Stations limits productivity and increases costs, especially when mapping large areas or long linear features such as roads or pipelines. <br><br> An alternative technique to DGNSS for high-accuracy positioning from GNSS is the so-called Precise Point Positioning or PPP method. In this case instead of differencing the rover observables with the Reference Station observables to cancel out common errors, an advanced model for every aspect of the GNSS error chain is developed and parameterized to within an accuracy of a few cm. The Trimble Centerpoint RTX positioning solution combines the methodology of PPP with advanced ambiguity resolution technology to produce cm level accuracies without the need for local reference stations. It achieves this through a global deployment of highly redundant monitoring stations that are connected through the internet and are used to determine the precise satellite data with maximum accuracy, robustness, continuity and reliability, along with advance algorithms and receiver and antenna calibrations. <br><br> This paper presents a new post-processed realization of the Trimble Centerpoint RTX technology integrated into the Applanix POSPac MMS GNSS-Aided Inertial software for mobile mapping. Real-world results from over 100 airborne flights evaluated against a DGNSS network reference are presented which show that the post-processed Centerpoint RTX solution agrees with the DGNSS solution to better than 2.9 cm RMSE Horizontal and 5.5 cm RMSE Vertical. Such accuracies are sufficient to meet the requirements for a majority of airborne mapping applications.

scholarly journals CENTIMETER-LEVEL, ROBUST GNSS-AIDED INERTIAL POST-PROCESSING FOR MOBILE MAPPING WITHOUT LOCAL REFERENCE STATIONS

2016 ◽  
Vol XLI-B3 ◽  
pp. 819-826 ◽  
Author(s):  
J. J. Hutton ◽  
N. Gopaul ◽  
X. Zhang ◽  
J. Wang ◽  
V. Menon ◽  
...  
Keyword(s):  
Inertial Sensors ◽  
Global Navigation Satellite Systems ◽  
Reference Station ◽  
Mobile Mapping ◽  
Satellite Systems ◽  
Local Reference ◽  
Set Up ◽  
Global Navigation Satellite ◽  
Airborne Mapping ◽  
Advanced Model

For almost two decades mobile mapping systems have done their georeferencing using Global Navigation Satellite Systems (GNSS) to measure position and inertial sensors to measure orientation. In order to achieve cm level position accuracy, a technique referred to as post-processed carrier phase differential GNSS (DGNSS) is used. For this technique to be effective the maximum distance to a single Reference Station should be no more than 20 km, and when using a network of Reference Stations the distance to the nearest station should no more than about 70 km. This need to set up local Reference Stations limits productivity and increases costs, especially when mapping large areas or long linear features such as roads or pipelines. &lt;br&gt;&lt;br&gt; An alternative technique to DGNSS for high-accuracy positioning from GNSS is the so-called Precise Point Positioning or PPP method. In this case instead of differencing the rover observables with the Reference Station observables to cancel out common errors, an advanced model for every aspect of the GNSS error chain is developed and parameterized to within an accuracy of a few cm. The Trimble Centerpoint RTX positioning solution combines the methodology of PPP with advanced ambiguity resolution technology to produce cm level accuracies without the need for local reference stations. It achieves this through a global deployment of highly redundant monitoring stations that are connected through the internet and are used to determine the precise satellite data with maximum accuracy, robustness, continuity and reliability, along with advance algorithms and receiver and antenna calibrations. &lt;br&gt;&lt;br&gt; This paper presents a new post-processed realization of the Trimble Centerpoint RTX technology integrated into the Applanix POSPac MMS GNSS-Aided Inertial software for mobile mapping. Real-world results from over 100 airborne flights evaluated against a DGNSS network reference are presented which show that the post-processed Centerpoint RTX solution agrees with the DGNSS solution to better than 2.9 cm RMSE Horizontal and 5.5 cm RMSE Vertical. Such accuracies are sufficient to meet the requirements for a majority of airborne mapping applications.

scholarly journals Asynchronous RTK Method for Detecting the Stability of the Reference Station in GNSS Deformation Monitoring

Sensors ◽  
2020 ◽  
Vol 20 (5) ◽  
pp. 1320
Author(s):  
Yuan Du ◽  
Guanwen Huang ◽  
Qin Zhang ◽  
Yang Gao ◽  
Yuting Gao
Keyword(s):  
Real Time ◽  
Reference Frame ◽  
Deformation Monitoring ◽  
Global Navigation Satellite Systems ◽  
Reference Station ◽  
Monitoring Station ◽  
Landslide Monitoring ◽  
Satellite Systems ◽  
Local Reference ◽  
Global Navigation Satellite

The real-time kinematic (RTK) positioning technique of global navigation satellite systems (GNSS) has been widely used for deformation monitoring in the past several decades. The RTK technique can provide relative displacements in a local reference frame defined by a highly stable reference station. However, the traditional RTK solution does not account for reference stations that experience displacement. This presents a challenge for establishing a near real-time GNSS monitoring system, as since the displacement of a reference station can be easily misinterpreted as a sign of rapid movement at the monitoring station. In this study, based on the reference observations in different time domains, asynchronous and synchronous RTK are proposed and applied together to address this issue, providing more reliable displacement information. Using the asynchronously generated time difference of a reference frame, the proposed approach can detect whether a measured displacement has occurred in the reference or the monitoring station in the current epoch. This allows for the separation of reference station movements from monitoring station movements. The results based on both simulated and landslide monitoring data demonstrate that the proposed method can provide reliable displacement determinations, which are critical in deformation monitoring applications, such as the early warning of landslides.

scholarly journals Reliable and Redundant RTK Positioning for Applications in Hard Observational Conditions

2012 ◽  
Vol 47 (1) ◽  
pp. 23-33 ◽  
Author(s):  
M. Bakuła ◽  
R. Pelc-Mieczkowska ◽  
M. Walawski
Keyword(s):  
Real Time ◽  
Computer Software ◽  
Global Navigation Satellite Systems ◽  
Advanced Technique ◽  
New Approach ◽  
Satellite Systems ◽  
The Common ◽  
Global Navigation Satellite ◽  
Forest Conditions

Reliable and Redundant RTK Positioning for Applications in Hard Observational ConditionsIt is well known that RTK (Real Time Kinematic) positioning is a very efficient technique for determination of coordinates in real time, directly on location. Although this technique has been well known since the mid-nineties of the last century, the common use of this technique developed since permanent reference GNSS (Global Navigation Satellite Systems) stations started operating as the national reference systems. Positioning in real time is very convenient for users who do not need to know any advanced technique of post-processing, especially in cases when no obstructions exist around the measured point exist. However, in practice, there are some situations when the use of RTK technique makes some difficulties, especially if the GNSS receiver has no full availability of satellites. Obstructions caused by trees, buildings, power lines etc. limit satellite availability and in consequence decrease the reliability of determined coordinates significantly. In those situations gross errors of even meters can appear in RTK positioning. In order to avoid misleading coordinates occurring we can use more than one RTK receiver simultaneously. The paper presents an approach to the RTK technology based on the simultaneous use of three different RTK receivers. Three different GNSS/RTK receivers can be set on a special mounting beam and additionally RTK positions are sent in real time to a computer. The computer software analyses not only the precision but also checks the accuracy and reliability of the RTK positions determined. Consequently, the new approach to RTK survey presented can allow obtaining reliable coordinates of centimeter accuracy even under very severe forest conditions.

scholarly journals Monitoramento estrutural em obras viárias utilizando a técnica RTK/NTRIP: Análise dos dados, desenvolvimento e implementação de um sistema de alerta posicional

2021 ◽  
Vol 10 (8) ◽  
pp. e3410816846
Author(s):  
Fabiane de Fátima Maciel ◽  
Herida dos Reis Silva ◽  
Fábio Luiz Albarici ◽  
Luciano Aparecido Barbosa ◽  
Jorge Luiz Alves Trabanco
Keyword(s):  
Real Time ◽  
Global Navigation Satellite Systems ◽  
Navigation Satellite ◽  
Satellite Systems ◽  
Real Time Kinematic ◽  
Global Navigation ◽  
Global Navigation Satellite

Desde a ampliação do sistema rodoviário no Brasil na década de 1930, tem-se um cenário com inúmeras obras viárias em diferentes condições de uso e segurança. Tal fato é preocupante devido à falta de monitoramento adequado em OAEs (Obras de Arte Especiais) e por quem de fato estas estruturas devem ser monitoradas. Estas estruturas estão sujeitas às ações de forças estáticas e dinâmicas, podendo causar deslocamentos e/ou deformações que se caracterizam por sua amplitude, direção e comportamento temporal. Há também processos de deteriorações, sejam por desgaste ao uso ou por solicitações naturais, levando-se ao enfraquecimento da estrutura. A incorporação de métodos de inspeção e monitoramento no comportamento estrutural em OAEs torna-se crescente devido ao alto custo de recuperação destas obras. Contudo, é necessário que haja um plano de monitoramento contínuo ou periódico, de acordo com as grandezas admissíveis de cada estrutura. A tecnologia dos GNSS (Global Navigation Satellite Systems) por meio da metodologia de levantamento RTK (Real Time Kinematic), mostrou-se capaz de oferecer suporte em tempo real no controle de deformações estruturais. Neste contexto, foi desenvolvido o SiGE (Sistema de Gerenciamento Estrutural) para monitoramento e emissão de alertas acerca de eventos previamente determinados pelo operador do sistema. Com a obtenção destes dados em tempo real, é possível avaliar a segurança da estrutura em serviço, monitorar a estrutura de forma contínua e segura e aprimorar projetos futuros com a definição de deslocamentos estruturais máximos.

Solar radio burst interference index dedicated to GNSS single and double frequency users

2020 ◽  
Author(s):  
Jean-Marie Chevalier ◽  
Nicolas Bergeot ◽  
Pascale Defraigne ◽  
Christophe Marque ◽  
Elisa Pinat
Keyword(s):  
Real Time ◽  
Solar Radio ◽  
Global Navigation Satellite Systems ◽  
Civil Aviation ◽  
International Gnss Service ◽  
Satellite Systems ◽  
Double Frequency ◽  
Weather Events ◽  
Gnss Measurements ◽  
Global Navigation Satellite

&lt;p&gt;Intense solar radio bursts (SRBs) emitted at L-band frequencies are a source of radio frequency interference for Global Navigation Satellite Systems (GNSS) by inducing a noise increase in GNSS measurements, and hence degrading the carrier-to-noise density (C/N&lt;sub&gt;0&lt;/sub&gt;). Such space weather events are critical for GNSS-based applications requiring real-time high-precision positioning.&lt;/p&gt;&lt;p&gt;Since 2015, the Royal Observatory of Belgium (ROB) monitors in near real-time the C/N&lt;sub&gt;0&lt;/sub&gt; observations from the European Permanent Network (EPN). The monitoring allows to detect accurately the general fades of C/N&lt;sub&gt;0&lt;/sub&gt; due to SRBs over Europe as from 1 dB-Hz. It provides in near real-time a quantification of the GNSS signal reception fade for the L1 C/A and L2 P(Y) signals and notifies civilian single and double frequency users with a 4-level index corresponding to the potential impact on their applications. This service is part of the real-time monitoring service of the PECASUS project of the International Civil Aviation Organization (ICAO) which started end of 2019.&lt;/p&gt;&lt;p&gt;Results of this 5-year monitoring will be discussed, including the 3 SRBs of 2015 and 2017, together with the new developments toward a global index using the International GNSS Service (IGS) network. In addition, we will show how the SRB monitoring is sometimes interfered by GPS flex power campaigns on the satellites from blocks IIR-M and IIF, and how it is mitigated . The routine and transient GPS flex power campaigns will be presented in terms of C/N&lt;sub&gt;0&lt;/sub&gt; variations for the EPN and IGS networks.&lt;/p&gt;

scholarly journals QUICK 3D WITH UAV AND TOF CAMERA FOR GEOMORPHOMETRIC ASSESSMENT

2020 ◽  
Vol XLIII-B1-2020 ◽  
pp. 259-264
Author(s):  
A. Masiero ◽  
G. Sofia ◽  
P. Tarolli
Keyword(s):  
High Resolution ◽  
Real Time ◽  
Low Cost ◽  
Wide Band ◽  
Global Navigation Satellite Systems ◽  
3D Reconstructions ◽  
Satellite Systems ◽  
Close Range ◽  
Tof Camera ◽  
Global Navigation Satellite

Abstract. Most of the high resolution topographic models are currently obtained either by means of Light Detection and Ranging (LiDAR) or photogrammetry: the former is usually preferred for producing very accurate models, whereas the latter is much more frequently used in low cost applications. In particular, the availability of more affordable Unmanned Aerial Vehicles (UAVs) equipped with high resolution cameras led to a dramatic worldwide increase of UAV photogrammetry-based 3D reconstructions. Nevertheless, accurate high resolution photogrammetric reconstructions typically require quite long data processing procedures, which make them less suitable for real-time applications.This work aims at investigating the use of a low cost Time of Flight (ToF) camera, combined with an Ultra-Wide Band (UWB) positioning system, mounted on a drone, in order to enable quasi real time 3D reconstructions of small to mid-size areas, even in locations where Global Navigation Satellite Systems (GNSSs) are not available.The proposed system, tested on a small area on the Italian Alps, provided high resolution mapping results, with an error of few centimeters with respect to a terrestrial close-range photogrammetry survey conducted on the same day.

Magnitude Calculation without Saturation from Strong-Motion Waveforms

2020 ◽  
Author(s):  
Zhang Hongcai ◽  
Diego Melgar ◽  
Dara E. Goldberg
Keyword(s):  
Real Time ◽  
Near Field ◽  
Magnitude Estimate ◽  
Strong Motion ◽  
Global Navigation Satellite Systems ◽  
Coseismic Deformation ◽  
Ground Displacement ◽  
Strong Motion Records ◽  
Satellite Systems ◽  
Global Navigation Satellite

ABSTRACT After destructive earthquakes, it is a challenge to estimate magnitude rapidly and accurately for dissemination to emergency responders and the public. Here, we propose criteria to calculate peak ground displacement (PGD) from strong-motion records, which can be used to calculate unsaturated event magnitude. Using collocated strong-motion and Global Navigation Satellite Systems observations of five major earthquakes in Japan, we demonstrate the effectiveness and accuracy of our strategy. Our results show that, with the right filtering criteria, PGD estimated from strong-motion acceleration waveforms is consistent with geodetic estimates. The methodology, however, does not allow for calculation of reliable estimates of coseismic deformation or other ground displacement metrics. We demonstrate a simulated real-time magnitude estimation that suggests it is feasible to generate an unsaturated magnitude estimate in real time from near-field strong-motion records. These findings have important implications for early warning and emergency response in seismically active areas, especially where real-time strong-motion data are more widely available than geodetic measurements.

scholarly journals Study the capabilities of RTK Multi GNSS under forest canopy in regions of Indonesia

2019 ◽  
Vol 94 ◽  
pp. 01021 ◽  
Author(s):  
Heri Andreas ◽  
Hasanuddin Zainal Abidin ◽  
Dina Anggreni Sarsito ◽  
Dhota Pradipta
Keyword(s):  
Real Time ◽  
Forest Canopy ◽  
Global Navigation Satellite Systems ◽  
Navigation Satellite ◽  
Satellite Systems ◽  
Position Accuracy ◽  
The Earth ◽  
Real Time Kinematic ◽  
The Future ◽  
Global Navigation Satellite

For more than two decade, the position on the earth can be precisely determined “real-time” in the order of few centimeters by Real Time Kinematic (RTK) GNSS (Global Navigation Satellite Systems) Method. Nevertheless, few limitations are still recognized such as degradation of accuracy against limited satellite visibilities (e.g. heavy satellite obstructions from forest canopy). It usually takes time to resolve the ambiguities or even in many occasion resulted in failure. Fortunately since recent years to the future seems more satellite systems beside GPS and GLONASS are being launched such as BEIDOU, GALILEO, QZSS, etc. It means that more satellite will be existed above the sky. The term GNSS has changed into Multi GNSS. This Multi GNSS is theoretically adding the value to previous GNSS System like GPS; problems of limited satellite visibilities (e.g. under forest canopy) to the position accuracy perhaps will reduce. Within this paper we try to do study the capabilities of RTK Multi GNSS under forest canopy in Indonesia. We observed by RTK in the forest areas which have canopy of 40 to 90 percent. As conclusion we found improvement in positioning result of even area of very limited satellite visibilities.

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