scholarly journals Repeated UAV Campaigns, GNSS Measurements, GIS, and Petrographic Analyses for Landslide Mapping and Monitoring

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 300
Author(s):  
Aggeliki Kyriou ◽  
Konstantinos Nikolakopoulos ◽  
Ioannis Koukouvelas ◽  
Paraskevi Lampropoulou
Keyword(s):  
Remote Sensing ◽  
Low Cost ◽  
Remote Sensing Data ◽  
Repeated Measurements ◽  
Global Navigation Satellite Systems ◽  
Landslide Monitoring ◽  
Integrated Monitoring ◽  
Satellite Systems ◽  
Gnss Measurements ◽  
Global Navigation Satellite

Landslides are posing a significant global hazard as they occur instantaneously with devastating consequences. The development of new remote sensing technologies and innovative processing techniques over the past few years opened up new horizons and perspectives in landslide monitoring research. The purpose of the current research is the integrated monitoring of an active landslide, located in Western Greece, using low-cost and high-repeatability remote sensing data like those obtained by unmanned aerial vehicles (UAVs). Repeated UAV campaigns and global navigation satellite systems (GNSS) surveys were performed to assess the activity of the landslide and determine its kinematic behavior. UAV data were processed using structure from motion (SfM) photogrammetry and the generated high-detailed orthophotos and digital surface models (DSMs) were submitted in further processing procedure in an ArcGIS environment. Regarding the GNSS data, a new low-cost technique for the estimation of the direction and the rate of movement of the displaced material was developed. The repeated measurements were displayed in a vector format in a three-axis diagram. In addition, GNSS measurements were used to verify the results of the photogrammetric processing. The final assessment was carried out taking into account geological data such as petrographic and crystallographic features of the material of the landslide. It was observed that the lithology and consequently the petrographic properties of the material plays a key role regarding the activity of the landslide.

scholarly journals GNSS-Reflectometry and Remote Sensing of Soil Moisture: A Review of Measurement Techniques, Methods, and Applications

2020 ◽  
Vol 12 (4) ◽  
pp. 614 ◽  
Author(s):  
Komi Edokossi ◽  
Andres Calabia ◽  
Shuanggen Jin ◽  
Iñigo Molina
Keyword(s):  
Remote Sensing ◽  
Soil Moisture ◽  
Land Surface ◽  
Low Cost ◽  
Measurement Techniques ◽  
Passive Microwave ◽  
Global Navigation Satellite Systems ◽  
Ecological Processes ◽  
Satellite Systems ◽  
Global Navigation Satellite

The understanding of land surface-atmosphere energy exchange is extremely important for predicting climate change and weather impacts, particularly the influence of soil moisture content (SMC) on hydrometeorological and ecological processes, which are also linked to human activities. Unfortunately, traditional measurement methods are expensive and cumbersome over large areas, whereas measurements from satellite active and passive microwave sensors have shown advantages for SMC monitoring. Since the launch of the first passive microwave satellite in 1978, more and more progresses have been made in monitoring SMC from satellites, e.g., the Soil Moisture Active and Passive (SMAP) and Soil Moisture and Ocean Salinity (SMOS) missions in the last decade. Recently, new methods using signals of opportunity have been emerging, highlighting the Global Navigation Satellite Systems-Reflectometry (GNSS-R), which has wide applications in Earth’s surface remote sensing due to its numerous advantages (e.g., revisiting time, global coverage, low cost, all-weather measurements, and near real-time) when compared to the conventional observations. In this paper, a detailed review on the current SMC measurement techniques, retrieval approaches, products, and applications is presented, particularly the new and promising GNSS-R technique. Recent advances, future prospects and challenges are given and discussed.

scholarly journals Global Navigation Satellite Systems Reflectometry as a Remote Sensing Tool for Agriculture

2012 ◽  
Vol 4 (8) ◽  
pp. 2356-2372 ◽  
Author(s):  
Alejandro Egido ◽  
Marco Caparrini ◽  
Giulio Ruffini ◽  
Simonetta Paloscia ◽  
Emanuele Santi ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Global Navigation Satellite Systems ◽  
Navigation Satellite ◽  
Satellite Systems ◽  
Global Navigation ◽  
Global Navigation Satellite

scholarly journals A Surface KInematics Buoy (SKIB) for wave-current interactions studies

2018 ◽  
Author(s):  
Pedro Veras Guimarães ◽  
Fabrice Ardhuin ◽  
Peter Sutherland ◽  
Mickael Accensi ◽  
Michel Hamon ◽  
...  
Keyword(s):  
Low Cost ◽  
Short Wave ◽  
Global Navigation Satellite Systems ◽  
Motion Sensor ◽  
Satellite Systems ◽  
Ocean Surface Waves ◽  
Sensing Applications ◽  
Hull Design ◽  
Sensor Package ◽  
Global Navigation Satellite

Abstract. Global Navigation Satellite Systems (GNSS) and modern motion-sensor packages allow the measurement of ocean surface waves with low-cost drifters. Drifting along or across current gradients provides unique measurements of wave-current interactions. In this study, we investigate the response of several combinations of GNSS receiver, motion-sensor package and hull design in order to define a prototype surface kinematic buoy (SKIB) that is particularly optimized for measuring wave-current interactions, including relatively short wave components (relative frequency around 1 Hz) that are important for air-sea interactions and remote sensing applications. The comparison with existing Datawell Directional Waverider and SWIFT buoys, as well as stereo-video imagery demonstrates the accuracy of SKIB. The use of low-cost accelerometers and a spherical ribbed and skirted hull design provide acceptable heave spectra, while velocity estimates from GNSS receivers yield a mean direction and directional spread. Using a low-power acquisition board allows autonomous deployments over several months with data transmitted by satellite. The capability to measure current-induced wave variations is illustrated with data acquired in a macro-tidal coastal environment.

scholarly journals Centimeter-Level Recording for All: Field Experimentation with New, Affordable Geolocation Technology

2019 ◽  
Vol 7 (4) ◽  
pp. 353-365 ◽  
Author(s):  
Peter J. Cobb ◽  
Tiffany Earley-Spadoni ◽  
Philip Dames
Keyword(s):  
Spatial Data ◽  
Field Data ◽  
Low Cost ◽  
Field Application ◽  
Global Navigation Satellite Systems ◽  
Precise Location ◽  
Satellite Systems ◽  
Surface Survey ◽  
Field Experimentation ◽  
Global Navigation Satellite

AbstractThe methodical recording and representation of spatial data are central to archaeological fieldwork and research. Until recently, centimeter-level precise geolocation equipment was the exclusive domain of researchers who could afford setups costing tens of thousands of dollars. However, high-quality measurements are being made more accessible by rapidly evolving technologies. These new tools, when used together with mobile technology for efficiently recording field data, open up the possibility of capturing the precise location of every find during an archaeological surface survey. An important step in reaching the desired outcome—centimeter-level recording for all—is experimentation with a variety of emerging low-cost setups. Accordingly, we tested the Reach and Reach RS, differential global navigation satellite systems (dGNSS) equipment produced by the company Emlid, during a surface survey in Armenia in June 2018. Our field application demonstrates that the use of dGNSS is already possible and that the described advances in precision enable improved recording and representation of spatial data.

scholarly journals Low cost GNSS receivers in time synchronization systems

2018 ◽  
Vol 67 (1) ◽  
pp. 65-72
Author(s):  
Grzegorz Czopik ◽  
Tomasz Kraszewski
Keyword(s):  
Time Synchronization ◽  
Low Cost ◽  
Global Navigation Satellite Systems ◽  
Satellite Systems ◽  
Time Frequency ◽  
Delay Times ◽  
Gnss Receivers ◽  
Frequency Counter ◽  
The One ◽  
Global Navigation Satellite

The GNSS (GNSS — Global Navigation Satellite Systems) receivers can be utilized to obtain accurate time markers. The preliminary results of the cheap GNSS receivers’ tests are presented in the paper. The one receiver’s price (including antenna) does not exceed 30 $. The studies on the use of receivers in the time synchronization systems were executed. Three identical models of receiver modules were used. The 1PPS (1PPS — 1 Pulse Per Second) signals available on the receiver’s output were used. The 1PPS’s main time characteristics were described. Delay times between different receivers 1PPS signals were measured. Measurements were taken using 1 GHz oscilloscope and precise time/frequency counter T3200U. Keywords: time synchronization, 1PPS, GNSS, GPS time

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 Enhanced Drone Navigation in GNSS Denied Environment Using VDM and Hall Effect Sensor

2019 ◽  
Vol 8 (4) ◽  
pp. 169 ◽  
Author(s):  
Shady Zahran ◽  
Adel Moussa ◽  
Naser El-Sheimy
Keyword(s):  
Hall Effect ◽  
Low Cost ◽  
Integrated System ◽  
Global Navigation Satellite Systems ◽  
Satellite Systems ◽  
Hall Effect Sensor ◽  
Aerial Vehicle ◽  
Heading Estimation ◽  
Global Navigation Satellite ◽  
Vehicle Dynamic Model

The last decade has witnessed a wide spread of small drones in many civil and military applications. With the massive advancement in the manufacture of small and lightweight Inertial Navigation System (INS), navigation in challenging environments became feasible. Navigation of these small drones mainly depends on the integration of Global Navigation Satellite Systems (GNSS) and INS. However, the navigation performance of these small drones deteriorates quickly when the GNSS signals are lost, due to accumulated errors of the low-cost INS that is typically used in these drones. During GNSS signal outages, another aiding sensor is required to bound the drift exhibited by the INS. Before adding any additional sensor on-board the drones, there are some limitations that must be taken into considerations. These limitations include limited availability of power, space, weight, and size. This paper presents a novel unconventional method, to enhance the navigation of autonomous drones in GNSS denied environment, through a new utilization of hall effect sensor to act as flying odometer “Air-Odo” and vehicle dynamic model (VDM) for heading estimation. The proposed approach enhances the navigational solution by estimating the unmanned aerial vehicle (UAV) velocity, and heading and fusing these measurements in the Extended Kalman Filter (EKF) of the integrated system.

scholarly journals New GNSS tomography of the atmosphere method – proposal and testing

2012 ◽  
Vol 9 ◽  
pp. 63-76 ◽  
Author(s):  
Michal Kačmařík ◽  
Lukáš Rapant
Keyword(s):  
Water Vapour ◽  
Theoretical Concept ◽  
Global Navigation Satellite Systems ◽  
Satellite Systems ◽  
Gnss Meteorology ◽  
Gnss Receivers ◽  
Tomography Method ◽  
Gnss Measurements ◽  
Global Navigation Satellite

Paper is focused on GNSS meteorology which is generally used for the determination of water vapour distribution in the atmosphere from GNSS measurements. Water vapour in the atmosphere is an important parameter which influences the state and development of the weather. At first, the paper presents basics of the GNSS meteorology and tomography of the atmosphere and subsequently introduces a new GNSS tomography method which doesn't require an extensive network of GNSS receivers, but uses only a few receivers situated in a line. After a theoretical concept describing this method and used mathematical background, the results from a real experiment are shown and discussed. Unfortunately the results indicate that presented method is not able to provide credible outputs. Possibly the main problem lies in an insufficient number of available signals from current global navigation satellite systems (GPS and GLONASS) where the improvement could be expected after the start of Galileo and Compass. Potential ways how to improve the results without increasing the number of satellites are outlined in the last section.

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