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Journal articles on the topic 'Space geodetic techniques'

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Published: 4 June 2021
Last updated: 1 February 2022

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1

Lösler, Michael, Cornelia Eschelbach, and Stefan Riepl. "A modified approach for automated reference point determination of SLR and VLBI telescopes." tm - Technisches Messen 85, no. 10 (October 25, 2018): 616–26. http://dx.doi.org/10.1515/teme-2018-0053.

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AbstractThe International Terrestrial Reference Frame (ITRF) is derived by combining several space geodetic techniques. Basically, a meaningful combination of the geodesic space techniques is impossible without further geometrical information, i. e. local-ties. Local-tie vectors are defined between the geometrical reference points of space geodetic techniques at co-location stations. These local-ties are introduced during the inter-technique combination process, to overcome the weak physical connection between the space geodetic techniques. In particular, the determination of the reference point of radio telescopes or laser telescopes is a challenging task and requires indirect methods. Moreover, the Global Geodetic Observing System (GGOS) strives for an automated and continued reference point determination with sub-millimeter accuracy, because deviations in local-ties bias global results.This investigation presents a modified approach for automated reference point determination. The new approach extends the prior work of Lösler but evades the synchronization between the terrestrial instrument and the telescope. Thus, synchronization errors are omitted and the technical effort is reduced. A proof of concept was carried out at Geodetic Observatory Wettzell in 2018. Using a high-precision, mobile laser-tracker, the reference point of the Satellite Observing System Wettzell (SOS-W) was derived. An extended version of the in-house developed software package HEIMDALL was employed for a mostly automated data collection. To evaluate the estimated reference point, the derived results are compared with the results of two approved models.
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2

Bianco, G., R. Devoti, M. Fermi, C. Ferraro, R. Lanotte, V. Luceri, A. Nardi, et al. "Investigation on the combination of space geodetic techniques." Journal of Geodynamics 30, no. 3 (February 2000): 337–53. http://dx.doi.org/10.1016/s0264-3707(99)00070-8.

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3

Lösler, Michael, Cornelia Eschelbach, Thomas Klügel, and Stefan Riepl. "ILRS Reference Point Determination Using Close Range Photogrammetry." Applied Sciences 11, no. 6 (March 20, 2021): 2785. http://dx.doi.org/10.3390/app11062785.

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A global geodetic reference system (GGRS) is realized by physical points on the Earth’s surface and is referred to as a global geodetic reference frame (GGRF). The GGRF is derived by combining several space geodetic techniques, and the reference points of these techniques are the physical points of such a realization. Due to the weak physical connection between the space geodetic techniques, so-called local ties are introduced to the combination procedure. A local tie is the spatial vector defined between the reference points of two space geodetic techniques. It is derivable by local measurements at multitechnique stations, which operate more than one space geodetic technique. Local ties are a crucial component within the intertechnique combination; therefore, erroneous or outdated vectors affect the global results. In order to reach the ambitious accuracy goal of 1 mm for a global position, the global geodetic observing system (GGOS) aims for strategies to improve local ties, and, thus, the reference point determination procedures. In this contribution, close range photogrammetry is applied for the first time to determine the reference point of a laser telescope used for satellite laser ranging (SLR) at Geodetic Observatory Wettzell (GOW). A measurement campaign using various configurations was performed at the Satellite Observing System Wettzell (SOS-W) to evaluate the achievable accuracy and the measurement effort. The bias of the estimates were studied using an unscented transformation. Biases occur if nonlinear functions are replaced and are solved by linear substitute problems. Moreover, the influence of the chosen stochastic model onto the estimates is studied by means of various dispersion matrices of the observations. It is shown that the resulting standard deviations are two to three times overestimated if stochastic dependencies are neglected.
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IWATA, Takahiro, Koji MATSUMOTO, Yoshiaki ISHIHARA, Fuyuhiko KIKUCHI, Yuji HARADA, and Sho SASAKI. "Measurements of Martian Rotational Variations by Space Geodetic Techniques." TRANSACTIONS OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES, AEROSPACE TECHNOLOGY JAPAN 10, ists28 (2012): Pk_25—Pk_29. http://dx.doi.org/10.2322/tastj.10.pk_25.

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5

Govind, R., J. Dawson, D. Sproule, and G. Luton. "Combination of high precision space geodetic techniques: The Asia and Pacific Regional Geodetic Project 1997." Advances in Space Research 23, no. 4 (January 1999): 797–807. http://dx.doi.org/10.1016/s0273-1177(99)00157-x.

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6

Lagler, K., M. Schindelegger, J. Böhm, H. Krásná, and T. Nilsson. "GPT2: Empirical slant delay model for radio space geodetic techniques." Geophysical Research Letters 40, no. 6 (March 22, 2013): 1069–73. http://dx.doi.org/10.1002/grl.50288.

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7

Guo, Jinyun, Qiaoli Kong, Jian Qin, and Yu Sun. "On precise orbit determination of HY-2 with space geodetic techniques." Acta Geophysica 61, no. 3 (January 24, 2013): 752–72. http://dx.doi.org/10.2478/s11600-012-0095-8.

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8

Robaudo, Stefano, and Christopher G. A. Harrison. "Measurements of strain at plate boundaries using space based geodetic techniques." Geophysical Research Letters 20, no. 17 (September 3, 1993): 1811–14. http://dx.doi.org/10.1029/93gl01380.

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9

Robbins, J. W. "Geophysics 1990: Regional deformation and global tectonics from space geodetic techniques." Eos, Transactions American Geophysical Union 72, no. 14 (1991): 162. http://dx.doi.org/10.1029/90eo00125.

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10

Boucher, C., and Z. Altamimi. "The use of space techniques for the connection of geodetic datums." Advances in Space Research 6, no. 9 (January 1986): 23–27. http://dx.doi.org/10.1016/0273-1177(86)90345-5.

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11

El-Rabbany, Ahmed. "Assessment of Hydrographic Data Uncertainty for Seamless Reference Surface." Journal of Navigation 59, no. 2 (April 6, 2006): 213–20. http://dx.doi.org/10.1017/s0373463306003729.

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The development of a seamless vertical reference surface is accompanied by a number of challenges pertinent to the availability, volume and uncertainty of bathymetric and topographic data. Data uncertainty, which is by far the most difficult to deal with, is attributed to various sources of errors including those of geodetic and hydrographic origin. The uncertainties in the geodetic measurements originate mainly from the limitations in the geodetic technique employed, i.e. terrestrial or space. Old nautical charts and topographic maps were based on terrestrial techniques, which are far less accurate than modern space techniques. In addition, the distribution of the positioning uncertainty is not expected to follow a consistent pattern across the chart (map). This is mainly due to the inconsistent datum distortion as well as the discrepancies in the measuring techniques in the subsequent chart (map) versions. The existing paper (and digitized) charts in many areas of the world were also based on old hydrographic surveying methods, for example the lead-line, which are far less accurate than modern techniques such as multibeam echo-sounding surveys. This creates inconsistent depth uncertainty across the chart. As uncertainties are propagated into the estimated transformation parameters, estimated positions and their covariance matrix, it is of utmost importance that they are properly modelled. This paper addresses the issue of uncertainty in hydrographic data and suggests ways to account for it.
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12

Lahaye, François, Giancarlo Cerretto, and Patrizia Tavella. "GNSS geodetic techniques for time and frequency transfer applications." Advances in Space Research 47, no. 2 (January 2011): 253–64. http://dx.doi.org/10.1016/j.asr.2010.05.032.

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13

Dettmering, Denise, Robert Heinkelmann, and Michael Schmidt. "Systematic differences between VTEC obtained by different space-geodetic techniques during CONT08." Journal of Geodesy 85, no. 7 (May 4, 2011): 443–51. http://dx.doi.org/10.1007/s00190-011-0473-z.

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14

Hernández-Pajares, Manuel, J. Miguel Juan, Jaume Sanz, Àngela Aragón-Àngel, Alberto García-Rigo, Dagoberto Salazar, and Miquel Escudero. "The ionosphere: effects, GPS modeling and the benefits for space geodetic techniques." Journal of Geodesy 85, no. 12 (September 11, 2011): 887–907. http://dx.doi.org/10.1007/s00190-011-0508-5.

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15

Kulkarni, Madhav N. "Monitoring Earth Rotation and Polar Motion Using Space VLBI: A Feasibility Study." Symposium - International Astronomical Union 156 (1993): 195–202. http://dx.doi.org/10.1017/s007418090017319x.

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Space Very Long Baseline Interferometry is an extension of the ground based VLBI to the space. With the launching of two Space VLBI satellites in the future, Space VLBI observations will be available for astrometric, geodetic and geodynamic applications. This new technique holds potential for various important applications including monitoring Earth rotation. The aim of this feasibility study has been to investigate the possibility of precise estimation of Earth rotation parameters from the Space VLBI observations. A simplified mathematical model is derived in terms of estimable parameters. Sensitivity analysis has been carried out to study the sensitivity of this system to the geodetic parameters of interest. Some of the dominant systematic effects have been investigated. Simulation studies have been carried out to study the influence of these systematic effects and a priori information on the estimation of the Earth rotation parameters. The results indicate that the Space VLBI technique may be used to complement other existing techniques for monitoring Earth rotation, only if the orbital systematic effects can be modeled to a high degree of accuracy (or the satellites can be tracked, with high accuracy, independently), and precise a priori information on station coordinates from other sources is used.
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16

Wu, Xiaoping, Jürgen Kusche, and Felix W. Landerer. "A new unified approach to determine geocentre motion using space geodetic and GRACE gravity data." Geophysical Journal International 209, no. 3 (March 3, 2017): 1398–402. http://dx.doi.org/10.1093/gji/ggx086.

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Abstract Geocentre motion between the centre-of-mass of the Earth system and the centre-of-figure of the solid Earth surface is a critical signature of degree-1 components of global surface mass transport process that includes sea level rise, ice mass imbalance and continental-scale hydrological change. To complement GRACE data for complete-spectrum mass transport monitoring, geocentre motion needs to be measured accurately. However, current methods of geodetic translational approach and global inversions of various combinations of geodetic deformation, simulated ocean bottom pressure and GRACE data contain substantial biases and systematic errors. Here, we demonstrate a new and more reliable unified approach to geocentre motion determination using a recently formed satellite laser ranging based geocentric displacement time-series of an expanded geodetic network of all four space geodetic techniques and GRACE gravity data. The unified approach exploits both translational and deformational signatures of the displacement data, while the addition of GRACE's near global coverage significantly reduces biases found in the translational approach and spectral aliasing errors in the inversion.
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17

Jordan, Thomas H., and J. Bernard Minster. "Beyond Plate Tectonics: Looking at Plate Deformation with Space Geodesy." Symposium - International Astronomical Union 129 (1988): 341–50. http://dx.doi.org/10.1017/s0074180900134941.

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We address the requirements that must be met by space-geodetic systems to place useful, new constraints on horizontal secular motions associated with the geological deformation of the earth's surface. Plate motions with characteristic speeds of about 50 mm/yr give rise to displacements that are easily observed by space geodesy. However, in order to improve the existing plate-motion models, the tangential components of relative velocities on interplate baselines must be resolved to an accuracy of < 3 mm/yr. Because motions considered small from a geodetic point of view have rather dramatic geological effects, especially when taken up as compression or extension of continental crust, detecting plate deformation by space-geodetic methods at a level that is geologically unresolvable places rather stringent requirements on the precision of the measurement systems: the tangential components on intraplate baselines must be observed with an accuracy of < 1 mm/yr. Among the measurements of horizontal secular motions that can be made by space geodesy, those pertaining to the rates within the broad zones of deformation characterizing the active continental plate boundaries are the most difficult to obtain by conventional ground-based geodetic and geological techniques. Measuring the velocities between crustal blocks to ± 5 mm/yr on 100-km to 1000-km length scales can yield geologically significant constraints on the integrated deformation rates across continental plate-boundary zones such as the western United States. However, baseline measurements in geologically complicated zones of deformation are useful only to the extent that the endpoints can be fixed in a local kinematical frame that includes major crustal blocks. For this purpose, the establishment of local geodetic networks around major VLBI and SLR sites in active areas should receive high priority.
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18

Marchandon, M., M. Vergnolle, O. Cavalié, H. Sudhaus, and J. Hollingsworth. "Earthquake sequence in the NE Lut, Iran: observations from multiple space geodetic techniques." Geophysical Journal International 215, no. 3 (September 5, 2018): 1604–21. http://dx.doi.org/10.1093/gji/ggy364.

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19

Gambis, D. "Monitoring Earth orientation using space-geodetic techniques: state-of-the-art and prospective." Journal of Geodesy 78, no. 4-5 (September 10, 2004): 295–303. http://dx.doi.org/10.1007/s00190-004-0394-1.

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20

Camacho and Fernández. "Modeling 3D Free-geometry Volumetric Sources Associated to Geological and Anthropogenic Hazards from Space and Terrestrial Geodetic Data." Remote Sensing 11, no. 17 (August 29, 2019): 2042. http://dx.doi.org/10.3390/rs11172042.

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Recent decades have shown an explosion in the quantity and quality of geodetic data, mainly space-based geodetic data, that are being applied to geological and anthropogenic hazards. This has produced the need for new approaches for analyzing, modeling and interpreting these geodetic data. Typically, modeling of deformation and gravity changes follows an inverse approach using analytical or numerical solutions, where normally regular geometries (point sources, disks, prolate or oblate spheroids, etc.) are assumed at the initial stages and the inversion is carried out in a linear context. Here we review an original methodology for the simultaneous, nonlinear inversion of gravity changes and/or surface deformation (measured with different techniques) to determine 3D (three-dimensional) bodies, without any a priori assumption about their geometries, embedded into an elastic or poroelastic medium. Such a fully nonlinear inversion has led to interesting results in volcanic environments and in the study of water tables variation due to its exploitation. This methodology can be used to invert geodetic remote sensing data or terrestrial data alone, or in combination.
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21

Kodet, J., K. U. Schreiber, J. Eckl, C. Plötz, S. Mähler, T. Schüler, T. Klügel, and S. Riepl. "Co-location of space geodetic techniques carried out at the Geodetic Observatory Wettzell using a closure in time and a multi-technique reference target." Journal of Geodesy 92, no. 9 (January 17, 2018): 1097–112. http://dx.doi.org/10.1007/s00190-017-1105-z.

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22

Zerbini, Susanna, Sara Bruni, Maddalena Errico, and Efisio Santi. "Observing the earth at regional and local scale by means of space geodetic techniques." Rendiconti Lincei. Scienze Fisiche e Naturali 29, S1 (September 6, 2017): 41–49. http://dx.doi.org/10.1007/s12210-017-0638-7.

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23

Suara, Gafar, and Timothy Oluwadare Idowu. "Optimum Techniques for the Conversion of Space Rectangular and Curvilinear Coordinates." European Journal of Engineering Research and Science 4, no. 10 (October 28, 2019): 147–51. http://dx.doi.org/10.24018/ejers.2019.4.10.1588.

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Conversion between space rectangular (X, Y, Z) and curvilinear (φ, λ, h) coordinates is an important task in the field of Surveying, geodesy, positioning, navigation, mapping etc. Different techniques which include iterative methods, non-iterative techniques and closed form algebraic methods have been applied over the years to carry out the coordinate conversion. However, the results obtained using these techniques are deficient in one way or the other due to the inherent limitations such as inability to produce results for curvilinear coordinates when the values of X, Y and Z are subsequently or simultaneously equal to zero. Therefore, this study attempts to put forth an optimum coordinate conversion technique between space rectangular and curvilinear coordinates. The data used are coordinates of points which include the space rectangular coordinates and their equivalent curvilinear coordinates. They were observed and processed in Nigeria using Doppler 9 software by African Doppler Survey (ADOS) and they were confirmed to be of first order accuracy and hence of high quality. The data processing involved the design of the optimum techniques equations, coding of the algorithms and necessary computations to obtain results. Analyzing the results obtained, it can be inferred that the designed optimum model has successfully carried out the conversion between space rectangular and curvilinear coordinates. Therefore, the optimum technique model is recommended for use for the conversions from Space rectangular coordinates to Geocentric, Geodetic, Reduced coordinates and vice versa.
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24

Schutz, B. E. "New Observational Techniques and Precise Orbit Determination of Artificial Satellites." International Astronomical Union Colloquium 165 (1997): 79–85. http://dx.doi.org/10.1017/s025292110004639x.

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AbstractModern observational techniques using ground-based and space-based instrumentation have enabled the measurement of the distance between the instrument and satellite to better than one centimeter. Such high precision instrumentation has fostered applications with centimeter-level requirements for satellite position knowledge. The determination of the satellite position to such accuracy requires a comparable modeling of the forces experienced by the satellite, especially when classical orbit determination methods are used. Geodetic satellites, such as Lageos, in conjunction with high precision ground-based laser ranging, have been used to improve for modeling of forces experienced by the satellite. Space-based techniques, such as Global Positioning System (GPS), offer alternatives, including kinematic techniques which require no modeling of the satellite forces, or only rudimentary models. This paper will describe the various techniques and illustrate the accuracies achieved with current satellites, such as TOPEX/POSEIDON, GPS/MET and the expectations for some future satellites.
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25

He, Bing, Xiao-Ya Wang, Xiao-Gong Hu, and Qun-He Zhao. "Combination of terrestrial reference frames based on space geodetic techniques in SHAO: methodology and main issues." Research in Astronomy and Astrophysics 17, no. 9 (September 2017): 089. http://dx.doi.org/10.1088/1674-4527/17/9/89.

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26

Gambis, D., and C. Bizouard. "Monitoring UT1 from astro-geodetic techniques at the EOP Center of the IERS." Proceedings of the International Astronomical Union 5, H15 (November 2009): 207–8. http://dx.doi.org/10.1017/s1743921310008781.

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AbstractMonitoring the Earth rotation is essential in various domains linked to reference frames firstly with applications in orbit determination, space geodesy or Astronomy. Secondly for geophysical studies where are involved mass motions within the different external fluid layers, atmosphere, hydrosphere, core and mantle of the earth, this on time scales ranging from a few hours to decades. The Earth Orientation Centre of the IERS is continuously monitoring the earth orientation variations from results derived from the various astro-geodetic techniques. It has in particular the task of deriving an optimal combined series of UT1 which is now based mainly on Very Long Baseline Interferometry (VLBI) with some contribution of LOD derived from GPS. We give here a brief summary concerning the contribution of the various techniques to UT1 and in aprticular how the use of LOD derived from GPS can improve the combination. More details are available in Gambis (2004) and Bizouard and Gambis (2009) and the website http://hpiers.obspm.fr/eop-pc/
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27

Doukas, Ioannis D., Dimitrios Ampatzidis, and Vassileios Kampouris. "THE VALIDATION OF THE TRANSFORMATION BETWEEN AN OLD GEODETIC REFERENCE FRAME AND A MODERN REFERENCE FRAME, BY USING EXTERNAL SPACE TECHNIQUES SITES: THE CASE STUDY OF THE HELLENIC GEODETIC REFERENCE SYSTEM OF 1987." Boletim de Ciências Geodésicas 23, no. 3 (September 2017): 434–44. http://dx.doi.org/10.1590/s1982-21702017000300029.

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Abstract: Many of the old geodetic reference frames which realized in the previous decades using classical observations carry biases. These biases are mainly caused due to the problematic observations and/or the tectonic motion. That is the case of the official Greek geodetic reference frame which consists of classical and satellite observations. Herein, we present a rigorous approach of the reconstruction of the Greek official reference frame based on the modern geodetic reference frames and their ability to express the spatial position and the dynamic change of the stations. We applied the rigorous approach to ninety stations located in Greece and we compare it with the officially accepted procedure. We found a consistency at 59.4cm between the rigorous and the officially accepted approaches, respectively. The associated mean bias estimation was estimated at 51.4 cm, indicating the resistance of a rather large amount of systematic effects. In addition, the observed discrepancies between the two approaches show great inhomogeneity all over the country.
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28

Mazurkiewicz, Ewelina, Łukasz Ortyl, and Jerzy Karczewski. "Application of Geodetic Techniques for Antenna Positioning in a Ground Penetrating Radar Method." E3S Web of Conferences 35 (2018): 03005. http://dx.doi.org/10.1051/e3sconf/20183503005.

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The accuracy of determining the location of detectable subsurface objects is related to the accuracy of the position of georadar traces in a given profile, which in turn depends on the precise assessment of the distance covered by an antenna. During georadar measurements the distance covered by an antenna can be determined with a variety of methods. Recording traces at fixed time intervals is the simplest of them. A method which allows for more precise location of georadar traces is recording them at fixed distance intervals, which can be performed with the use of distance triggers (such as a measuring wheel or a hip chain). The search for methods eliminating these discrepancies can be based on the measurement of spatial coordinates of georadar traces conducted with the use of modern geodetic techniques for 3-D location. These techniques include above all a GNSS satellite system and electronic tachymeters. Application of the above mentioned methods increases the accuracy of space location of georadar traces. The article presents the results of georadar measurements performed with the use of geodetic techniques in the test area of Mydlniki in Krakow. A satellite receiver Leica system 1200 and a electronic tachymeter Leica 1102 TCRA were integrated with the georadar equipment. The accuracy of locating chosen subsurface structures was compared.
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29

Dickey, Jean O. "Earth Rotation Variations from Hours to Centuries." Highlights of Astronomy 10 (1995): 17–44. http://dx.doi.org/10.1017/s1539299600010339.

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AbstractThe study of Earth rotation encompasses the complex nature of orientation changes, the excitation of these changes and their geophysical implications in a broad variety of areas. Studies have embarked on a new era with the advent of highly accurate space geodetic techniques and the increasing availability of complementary geophysical data sets. This paper provides an overview of Earth rotation variations from hours to centuries with a brief discussion of polar motion and nutation results.
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30

Glaus, R., B. Bürki, and H. G. Kahle. "Recent results of water vapor radiometry in assessing vertical lithospheric movements by using space geodetic radiowave techniques." Journal of Geodynamics 20, no. 1 (September 1995): 31–39. http://dx.doi.org/10.1016/0264-3707(94)00024-p.

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31

Farolfi, Gregorio, Aldo Piombino, and Filippo Catani. "Fusion of GNSS and Satellite Radar Interferometry: Determination of 3D Fine-Scale Map of Present-Day Surface Displacements in Italy as Expressions of Geodynamic Processes." Remote Sensing 11, no. 4 (February 15, 2019): 394. http://dx.doi.org/10.3390/rs11040394.

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We present a detailed map of ground movement in Italy derived from the combination of the Global Navigation Satellite System (GNSS) and Satellite Synthetic Aperture Radar (SAR) interferometry. These techniques are two of the most used space geodetic techniques to study Earth surface deformation. The above techniques provide displacements with respect to different components of the ground point position; GNSSs use the geocentric International Terrestrial Reference System 1989 (ITRS89), whereas the satellite SAR interferometry components are identified by the Lines of Sight (LOSs) between a satellite and ground points. Moreover, SAR interferometry is a differential technique, and for that reason, displacements have no absolute reference datum. We performed datum alignment of InSAR products using precise velocity fields derived from GNSS permanent stations. The result is a coherent ground velocity field with detailed boundaries of velocity patterns that provide new information about the complex geodynamics involved on the Italian peninsula and about local movements.
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32

Zecevic, Megan, Thomas S. Eyre, and David W. Eaton. "Static Ground Displacement for an Induced Earthquake Recorded on Broadband Seismometers." Bulletin of the Seismological Society of America 110, no. 5 (August 4, 2020): 2216–24. http://dx.doi.org/10.1785/0120200074.

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ABSTRACT Using geodetic methods, significant static ground deformation has been observed for many large natural earthquakes. Some of the largest earthquakes induced by hydraulic-fracturing operations have been observed in the Western Canada Sedimentary Basin; however, because of the size and depths of these events, the associated static ground deformations have not yet been observed using traditional geodetic techniques. A seismic processing technique, developed for small volcano-seismic events, has the potential to resolve micrometer-scale static displacements using broadband seismic data. In this study, we test this processing method using vertical component broadband recordings of an Mw 4.1 event acquired at four nearby broadband seismometers. Estimated static displacements at the four stations are compared with the theoretical surface displacement field for a dislocation on a finite rectangular source within a homogeneous, elastic half-space. The theoretical displacements have the same polarities as the measured displacements across the seismic network and have similar amplitudes for three of the four stations. However, one station yielded unstable results, which shows that care must be taken when using this method. These results suggest that this processing method has potential for obtaining surface deformation for small to moderate-sized earthquakes using broadband data.
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33

Giniotis, Vytautas, and Darius Mariūnas. "ANALYSIS OF DISCRETISATION STRATEGY FOR AREA AND SPACE MEASUREMENT." Geodesy and cartography 31, no. 1 (August 3, 2012): 28–31. http://dx.doi.org/10.3846/13921541.2005.9636661.

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Measurement strategy is discussed in the article. It is important to optimise the data selection (sampling) from the object for the determination of its geometrical features within some limits of accuracy. The minimal and maximal intervals of measurement must be selected ensuring the maximal efficiency of operation and the accuracy as well. In machine engineering the typical case is in the calibration of coordinate measuring machines (CMMs) as it is a quite complicated task because of the variety of accuracy parameters to be checked and the high accuracy that must be assured. Some new techniques for the two- and three-dimensional measurements are discussed in this paper leading to a more efficient calibration process. This is relevant to machine engineering where geometric accuracy parameters are to be determined, to the geodetic measurements where slopes of terrain, area flatness and volumetric features are surveyed, in structural engineering, etc.
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Hellmers, Hendrik, Daniela Thaller, Mathis Bloßfeld, Alexander Kehm, and Anastasiia Girdiuk. "Combination of VLBI Intensive Sessions with GNSS for generating Low latency Earth Rotation Parameters." Advances in Geosciences 50 (December 10, 2019): 49–56. http://dx.doi.org/10.5194/adgeo-50-49-2019.

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Abstract. The Earth Orientation Parameters (EOPs) are published by the Earth Orientation Centre of the International Earth Rotation and Reference Systems Service (IERS). They are provided as the low-latency Bulletin A and the 30 d latency long-term EOP time series IERS 14 C04. The EOPs are a combined product derived from different geodetic space techniques, namely Global Navigation Satellite Systems (GNSS), Satellite Laser Ranging (SLR) and Lunar Laser Ranging (LLR), Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) and Very Long Baseline Interferometry (VLBI). Since not all techniques are equally sensitive to every EOP, several parameters rely on specific observation techniques. As an example, dUT1 can only be estimated from VLBI observations. This means VLBI is an essential part of the estimation procedure for consistent EOPs. Within this paper, we are performing a combination of two low-latency space geodetic techniques as they enable the estimation of the full set of Earth Rotation Parameters (ERPs; polar motion, dUT1 and the corresponding rates). In particular, we focus on the development of a robust combination scheme of 1 h VLBI Intensive sessions with so-called GNSS Rapid solutions on the normal equation level of the Gauß-Markov model. The aim of the study is to provide highly accurate low-latency ERPs. So far, a latency of approximately only 1–3 d cold be reached since the main limiting factor is still the latency of the input data. The mathematical background of the applied algorithm is discussed in detail and evaluated by numerical results of empirical investigations. The combination yields a numerical stabilization of the equation system as well as an improvement (reduction) of the corresponding root mean square deviation of the epoch-wise estimated parameters w.r.t. the IERS 14 C04 reference time series.
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Younes, Sobhy Abdel Monem, and Hafez Abbas Afify. "ACCURACY IMPROVEMENT OF TROPOSPHERIC DELAY CORRECTION MODELS IN SPACE GEODETIC DATA. CASE STUDY: EGYPT." Geodesy and cartography 40, no. 4 (December 16, 2014): 148–55. http://dx.doi.org/10.3846/20296991.2014.987465.

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The tropospheric delay still remains a limiting factor to the accuracy of space based positioning techniques. The estimation of station positioning, especially height component, which is particularly important for more applications is susceptible to errors in modeling the tropospheric delay due to correlations between the station positioning and residual troposphere delay parameters. As the demand on positioning accuracy and precision has increased, it has begun a necessary of relaying on large external data sets, rather than relatively simple models for treating the tropospheric delay. This method has been possible by advances made in numerical weather models which provide accurate representations of global atmospheric conditions and by advances in computing speed which allow us to perform a large number of computations over a short period of time. The purpose of this work is to develop a new model for estimating the tropospheric delay and then assess the benefits of applying this model at various geographic atmospheric conditions of Egypt. By comparing new model with some common models such as Saastamoinen model, Hopfield model, Niell-MF, Black & Eisner-MF, UNB3 model and Vienna-MF, the results show that, new model for estimation tropospheric delay has an acceptable level of accuracy in describing the dry tropospheric delay in Egypt as it agrees closely with the numerical integration based model. The mean accuracy of this new model has been assessed to be about 9.64 mm with rms 11 mm at an elevation angle of 30° and for an elevation angle of 5°, the mean accuracy is about 83.23 mm with rms 96.42 mm for atmospheric conditions of Egypt.
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Hang, Yu, Sylvain Barbot, Justin Dauwels, Teng Wang, Priyamvada Nanjundiah, and Qiang Qiu. "Outlier-insensitive Bayesian inference for linear inverse problems (OutIBI) with applications to space geodetic data." Geophysical Journal International 221, no. 1 (December 12, 2019): 334–50. http://dx.doi.org/10.1093/gji/ggz559.

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SUMMARY Inverse problems play a central role in data analysis across the fields of science. Many techniques and algorithms provide parameter estimation including the best-fitting model and the parameters statistics. Here, we concern ourselves with the robustness of parameter estimation under constraints, with the focus on assimilation of noisy data with potential outliers, a situation all too familiar in Earth science, particularly in analysis of remote-sensing data. We assume a linear, or linearized, forward model relating the model parameters to multiple data sets with a priori unknown uncertainties that are left to be characterized. This is relevant for global navigation satellite system and synthetic aperture radar data that involve intricate processing for which uncertainty estimation is not available. The model is constrained by additional equalities and inequalities resulting from the physics of the problem, but the weights of equalities are unknown. We formulate the problem from a Bayesian perspective with non-informative priors. The posterior distribution of the model parameters, weights and outliers conditioned on the observations are then inferred via Gibbs sampling. We demonstrate the practical utility of the method based on a set of challenging inverse problems with both synthetic and real space-geodetic data associated with earthquakes and nuclear explosions. We provide the associated computer codes and expect the approach to be of practical interest for a wide range of applications.
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Sánchez, José L. Carrión, Sílvio R. C. de Freitas, and Riccardo Barzaghi. "OFFSET EVALUATION OF THE ECUADORIAN VERTICAL DATUM RELATED TO THE IHRS." Boletim de Ciências Geodésicas 24, no. 4 (December 2018): 503–25. http://dx.doi.org/10.1590/s1982-21702018000400031.

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Abstract Considering the definition of the International Height Reference System (IHRS) in the geopotential space (Resolution 1/2015, International Association of Geodesy - IAG), among the present main objectives of the international geodetic community is the materialization of IHRS around the world. One fundamental task for this is the offset determination of each national vertical datum related to the IHRS. In this manuscript we establish the relationship between the Ecuadorian Vertical Datum (EVD) and the IHRS in the geopotential space following the foundations of the Resolution 1/2015 IAG. Gravity data, heights from the Ecuadorian Fundamental Vertical Network, Global Geopotential Models and Digital Elevation Models were used in the computations. Based on the Least Squares Collocation method, empirical covariance functions and spectral decomposition techniques, we realized the modelling of the geopotential in the study region (4° x 4° centered in the La Libertad tide gauge, Ecuador). Based on the referred approaches, we solved the free Geodetic Boundary Value Problem for determining the discrepancy of the EVD related to the IHRS. An offset of approximately 29 cm ± 3 cm was estimated for the W 0 - W 0 i relation when the GO_CONS_GCF_2_DIR_R5 model was used in the modeling of the medium and long wavelengths of the terrestrial gravity field, and approximately 43 cm ± 3 cm when the EIGEN6C4 model was used.
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Teke, Kamil, Tobias Nilsson, Johannes Böhm, Thomas Hobiger, Peter Steigenberger, Susana García-Espada, Rüdiger Haas, and Pascal Willis. "Troposphere delays from space geodetic techniques, water vapor radiometers, and numerical weather models over a series of continuous VLBI campaigns." Journal of Geodesy 87, no. 10-12 (October 10, 2013): 981–1001. http://dx.doi.org/10.1007/s00190-013-0662-z.

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39

Vitagliano, Eleonora, Umberto Riccardi, Ester Piegari, Jean-Paul Boy, and Rosa Di Maio. "Multi-Component and Multi-Source Approach for Studying Land Subsidence in Deltas." Remote Sensing 12, no. 9 (May 5, 2020): 1465. http://dx.doi.org/10.3390/rs12091465.

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The coupled effects of climate change and land sinking make deltas and coastal areas prone to inundation and flooding, meaning that reliable estimation of land subsidence is becoming crucial. Commonly, land subsidence is monitored by accurate continuous and discrete measurements collected by terrestrial and space geodetic techniques, such as Global Navigation Satellite System (GNSS), Interferometry Synthetic Aperture Radar (InSAR), and high precision leveling. In particular, GNSS, which includes the Global Positioning System (GPS), provides geospatial positioning with global coverage, then used for deriving local displacements through time. These site-positioning time series usually exhibit a linear trend plus seasonal oscillations of annual and semi-annual periods. Although the periodic components observed in the geodetic signal affect the velocity estimate, studies dealing with the prediction and prevention of risks associated with subsidence focus mainly on the permanent component. Periodic components are simply removed from the original dataset by statistical analyses not based on the underlying physical mechanisms. Here, we propose a systematic approach for detecting the physical mechanisms that better explain the permanent and periodic components of subsidence observed in the geodetic time series. It consists of three steps involving a component recognition phase, based on statistical and spectral analyses of geodetic time series, a source selection phase, based on their comparison with data of different nature (e.g., geological, hydro-meteorological, hydrogeological records), and a source validation step, where the selected sources are validated through physically-based models. The application of the proposed procedure to the Codigoro area (Po River Delta, Northern Italy), historically affected by land subsidence, allowed for an accurate estimation of the subsidence rate over the period 2009–2017. Significant differences turn out in the retrieved subsidence velocities by using or not periodic trends obtained by physically based models.
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40

Reilinger, Robert. "Geodetic Evidence for Tectonic Deformation in the Eastern United States." Seismological Research Letters 59, no. 4 (October 1, 1988): 314. http://dx.doi.org/10.1785/gssrl.59.4.314.

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Abstract The historic geodetic data base in the eastern United States dates back over 100 years. Although instrumentation and hence measurement precision has improved since the initial observations, the basic techniques [leveling, triangulation, water level gauging] remained unchanged until the recent introduction of space geodesy [Very Long Baseline Interferometry (VLBI), Satellite Laser Ranging (SLR), Global Positioning System (GPS)]. Because of this, it has been possible to compare repeated observations to identify apparent changes in relative positions. Such “changes” can reflect observational errors, non-tectonic movements (water level effects, monument instability, loading, etc.) or tectonic/isostatic deformation. A number of possible deformation features in the eastern U. S. have been reported in the literature, including uplift of the southern Appalachian and Adirondack mountains, doming of the Gulf coast inland of the Mississippi delta, subsidence of Chesapeak Bay and along the coast of Maine, horizontal deformation in New York and Connecticut, and possible fault related deformation near Charleston and in the New Madrid area. Unfortunately, it is not dear to what extent any of these features represent tectonic deformations and hence what their significance may be for the earthquake problem. An important recent development in monitoring regional deformation has been the establishment of the eastern U. S. GPS strain network by the National Geodetic Survey. The network consists of roughly 45 sites uniformly distributed east of the Rocky Mountains. The network was established in 1987 and will be reobserved in 1989. Subsequent reobservations will be made at 2 to 5 year intervals depending on analysis of the early measurements. Given the precision of the GPS measurements (few cm in 3-D relative positions), a considerable time period will be required to detect the subtle deformations expected for this intraplate region. Perhaps more immediate information will result from recent progress in recognizing and correcting systematic errors in the historic geodetic data base. This, together with the newly automated historic data base, and improved techniques for integrating and analyzing these extensive observations, provide the necessary basis for effectively evaluating the deformational features listed above. Given the potential importance of these data for understanding tectonic processes (and the huge expense of collecting these measurements over the pst century), such studies should be an integral part of future earthquake studies in the eastern U. S.
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Dimc, Franc, Polona Pavlovčič-Prešeren, and Matej Bažec. "Robustness against Chirp Signal Interference of On-Board Vehicle Geodetic and Low-Cost GNSS Receivers." Sensors 21, no. 16 (August 4, 2021): 5257. http://dx.doi.org/10.3390/s21165257.

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Robust autonomous driving, as long as it relies on satellite-based positioning, requires carrier-phase-based algorithms, among other types of data sources, to obtain precise and true positions, which is also primarily true for the use of GNSS geodetic receivers, but also increasingly true for mass-market devices. The experiment was conducted under line-of-sight conditions on a straight road during a period of no traffic. The receivers were positioned on the roof of a car travelling at low speed in the presence of a static jammer, while kinematic relative positioning was performed with the static reference base receiver. Interference mitigation techniques in the GNSS receivers used, which were unknown to the authors, were compared using (a) the observed carrier-to-noise power spectral density ratio as an indication of the receivers’ ability to improve signal quality, and (b) the post-processed position solutions based on RINEX-formatted data. The observed carrier-to-noise density generally exerts the expected dependencies and leaves space for comparisons of applied processing abilities in the receivers, while conclusions on the output data results comparison are limited due to the non-synchronized clocks of the receivers. According to our current and previous results, none of the GNSS receivers used in the experiments employs an effective type of complete mitigation technique adapted to the chirp jammer.
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42

Krishna, S., J. Mathew, R. Majumdar, P. Roy, and K. Vinod Kumar. "Geodynamics of the Indian Lithospheric Plate relative to the neighbouring Plates as revealed by Space Geodetic Measurements." ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL-8 (November 27, 2014): 53–56. http://dx.doi.org/10.5194/isprsarchives-xl-8-53-2014.

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The Indian Plate is highly dynamic in nature which in turn makes the Indo-Eurassian collision zone the foci of most of the historic large magnitude earthquakes. Processing of positional information from continuously observing reference stations is one of the space based geodetic techniques used globally and nationally to understand the crustal dynamics. The present study evaluates the dynamic nature of the Indian plate relative to its adjoining plates using the permanent GPS data (2011 to 2013) of 12 International GNSS Service (IGS), which are spread across the Indian, Eurassian, Australian, Somaliyan and African plates. The data processing was carried out using GAMIT/GLOBK software. The results indicate that the average velocity for the two IGS stations on the Indian Plate (Hyderabad and Bangalore) is 54.25 mm/year towards NE in the ITRF-2008 reference frame. The relative velocity of various stations with respect to the Indian plate has been estimated using the Bangalore station and has been found that the stations in the Eurasian plate (Lhasa, Urumqi, Bishkek and Kitab) are moving with velocity ranging from 25 to 33 mm/year in the SE direction resulting in compressional interaction with the Indian plate. This study reveals and confirms to the previous studies that the Indian- Eurassian-Australian Plates are moving at different relative velocities leading to compressional regimes at their margins leading to seismicity in these zones.
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43

Wilkins, G. A. "The Terrestrial Coordinate System and International Earth-rotation Services." Journal of Navigation 38, no. 02 (May 1985): 216–17. http://dx.doi.org/10.1017/s0373463300031337.

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New techniques of measurement make it possible in 1984 to determine positions on the surface of the Earth to a much higher precision than was possible in 1884. If we look beyond the requirements of navigation we can see useful applications of global geodetic positioning to centimetric accuracy for such purposes as the control of mapping and the study of crustal movements. These new techniques depend upon observations of external objects, such as satellites or quasars rather than stars, and they require that the positions of these objects and the orientation of the surface of the Earth are both known with respect to an appropriate external reference system that is ‘fixed’ in space. We need networks of observing stations and analysis centres that monitor the motions of the external objects and the rotation of the Earth. Observations of stars by a transit circle are no longer adequate for this purpose.
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Kong, Qiaoli, Linggang Zhang, Litao Han, Jinyun Guo, Dezhi Zhang, and Wenhao Fang. "Analysis of 25 Years of Polar Motion Derived from the DORIS Space Geodetic Technique Using FFT and SSA Methods." Sensors 20, no. 10 (May 16, 2020): 2823. http://dx.doi.org/10.3390/s20102823.

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Polar motion (PM) has a close relation to the Earth’s structure and composition, seasonal changes of the atmosphere and oceans, storage of waters, etc. As one of the four major space geodetic techniques, doppler orbitography and radiopositioning integrated by satellite (DORIS) is a mature technique that can monitor PM through precise ground station positioning. There are few articles that have analyzed the PM series derived by the DORIS solution in detail. The aim of this research was to assess the PM time-series based on the DORIS solution, to better capture the time-series. In this paper, Fourier fast transform (FFT) and singular spectrum analysis (SSA) were applied to analyze the 25 years of PM time-series solved by DORIS observation from January 1993 to January 2018, then accurately separate the trend terms and periodic signals, and finally precisely reconstruct the main components. To evaluate the PM time-series derived from DORIS, they were compared with those obtained from EOP 14 C04 (IAU2000). The results showed that the RMSs of the differences in PM between them were 1.594 mas and 1.465 mas in the X and Y directions, respectively. Spectrum analysis using FFT showed that the period of annual wobble was 0.998 years and that of the Chandler wobble was 1.181 years. During the SSA process, after singular value decomposition (SVD), the time-series was reconstructed using the eigenvalues and corresponding eigenvectors, and the results indicated that the trend term, annual wobble, and Chandler wobble components were accurately decomposed and reconstructed, and the component reconstruction results had a precision of 3.858 and 2.387 mas in the X and Y directions, respectively. In addition, the tests also gave reasonable explanations of the phenomena of peaks of differences between the PM parameters derived from DORIS and EOP 14 C04, trend terms, the Chandler wobble, and other signals detected by the SSA and FFT. This research will help the assessment and explanation of PM time-series and will offer a good method for the prediction of pole shifts.
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45

Kluykov, A. A. "Determination of vector Euler parameters." Geodesy and Cartography 932, no. 2 (March 20, 2018): 2–9. http://dx.doi.org/10.22389/0016-7126-2018-932-2-2-9.

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Improving the accuracy of points coordinates determination from geodetic networks with the use of modern space geodesy techniques (GPS, SLR, VLBI, DORIS) identified factors that were earlier considered as insignificant. Such factors include the movement of tectonic plates. This made possible the transition from the static coordinate system model to the kinematic one. For the effect of the tectonic plates movement on the points coordinates you must know kinematic parameters of the tectonic plates movement – the Euler vector parameters – angular velocity of the tectonic plates rotation and the poles rotation coordinates (latitude and longitude) of tectonic plates. Many modern kinematic models of tectonic plates are used observations, performed by geophysical methods, to estimate kinematic parameters of the tectonic plates movement. The article presents the algorithm that allows to estimate the parameters of the tectonic plates movement from mathematical processing of geodetic measurements carried out at points distributed over the surface of tectonic plates. Based on the presented algorithm the EULER program was developed in the algorithmic FORTRAN language, which was experimentally tested. The analysis results showed that the parameters of the Euler vector obtained by the EULER program are in good agreement with the results obtained by using ITRF 2005 and ITRF 2008 models.
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46

Amarjargal, Sharav, and Gankhuyag Bulgan. "On the modernization of National Geodetic Network with GNSS CORS Reference Frame." Mongolian Geoscientist, no. 48 (July 4, 2019): 28–39. http://dx.doi.org/10.5564/mgs.v0i48.1146.

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New technical developments, growing applications and requests for higher accuracy in georeferencing of national reference frame raise a demand on high accuracy National Terrestrial Reference Frame based on Global Navigation Satellite System (GNSS) and other space geodetic techniques. Since the last decades many countries decided to switch main geodetic control points from triangulation points to Continuously Operating Reference Stations (CORS). This task is currently undertaken by the geodetic authority of Mongolia in collaboration with research and private organizations. The first continuous Global Positioning System (GPS) station in Mongolia became operational in the late 1995 for the global geodetic scientific applications. Since 1997 the survey-mode GPS observations were utilized in Mongolia for crustal deformation studies and for re-survey of the national triangulation network. During the years 2011-2013 CORS network of nearly 18 stations has been built to modernize the old geodetic network. Currently the total number of the reference stations counts to nearly 40. Since Mongolia is located in the tectonically active region, its geodetic reference frame is continuously deforming, which requires regular updates of reference frame. In this paper we discuss the technical issues of the national reference frame of Mongolia considering the crustal deformation of Mongolia and the data management of the national CORS network. Үндэсний геодезийн сүлжээг GNSS CORS тулгуур тогтолцоогоор шинэчлэх асуудалд Хураангуй: Техникийн шинэчлэл болон өндөр нарийвчлалтай газарзүйн холболт хийх хэрэгцээ, шаардлагын өсөлт нь Глобаль Навигацийн Дагуулын Систем болон бусад сансрын геодезийн техникт суурилсан илүү өндөр нарийвчлалтай Үндэсний Тулгуур Тогтолцоог шаардах боллоо. Сүүлийн арваад жилд олон улс орон геодезийн хяналтын цэгүүдээ триангуляцийн цэгээс байнгын ажиллагаатай тулгуур станцаар орлуулах үйл ажиллагаа явуулж эхэлсэн бөгөөд хөгжингүй орнууд динамик тогтолцоо руу шилжиж байна. Энэ ажлыг Монгол улсад Газрын Харилцаа Геодези Зурагзүйн Газар толгойлон судалгааны болон хувийн хэвшлийн байгууллагуудтай хамтран хэрэгжүүлж байгаа билээ. Байнгын ажиллагаатай GPS станц Монголд анх 1995 оны сүүлээс ажиллаж эхэлсэн бөгөөд геодезийн шинжлэх ухааны глобаль хэрэглээнд зориулагдаж байв. 1997 оноос эхлэн давтан хэмжилтийн GPS ажиглалтуудыг царцдасын деформац болон триангуляцийн сүлжээг хэмжихэд ашиглаж эхлэв. 2011-2013 оны хооронд триангуляцийн сүлжээг шинэчлэх зориулалтаар ~18 байнгын ажиллагаатай тулгуур станцуудын сүлжээ байгуулагдсан бөгөөд эдгээр станцуудын тоо одоо 40 гарсан байна. Монгол улсын нутаг дэвсгэр нь тектоникийн идэвхтэй бүс нутагт оршдог тул геодезийн тулгуур тогтолцоо нь байнгын деформацд байна. Тиймээс тулгуур тогтолцоог тогтмол шинэчилж байх шаардлагатай. Энэ өгүүлэлд бид үндэсний тулгуур тогтолцооны техник нөхцлийг байнгын ажиллагаатай станцуудын ажиллагаа, Монгол орны царцдасын деформацыг тооцон тусгасан бөгөөд үндэсний CORS (Байнгын Ажиллагаатай Тулгуур Станцын) сүлжээний өгөгдөл, түүний зохицуулалтын талаар илтгэх болно. Түлхүүр үг: GPS геодези, царцдасын деформацын мониторинг, геодезийн сүлжээ
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47

Özyaşar, M., and M. T. Özlüdemir. "The contribution of engineering surveys by means of GPS to the determination of crustal movements in Istanbul." Natural Hazards and Earth System Sciences 11, no. 6 (June 17, 2011): 1705–13. http://dx.doi.org/10.5194/nhess-11-1705-2011.

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Abstract. Global Navigation Satellite Systems (GNSS) are space based positioning techniques and widely used in geodetic applications. Geodetic networking accomplished by engineering surveys constitutes one of these tasks. Geodetic networks are used as the base of all kinds of geodetic implementations, Co from the cadastral plans to the relevant surveying processes during the realization of engineering applications. Geodetic networks consist of control points positioned in a defined reference frame. In fact, such positional information could be useful for other studies as well. One of such fields is geodynamic studies that use the changes of positions of control stations within a network in a certain time period to understand the characteristics of tectonic movements. In Turkey, which is located in tectonically active zones and struck by major earthquakes quite frequently, the positional information obtained in engineering surveys could be very useful for earthquake related studies. For this purpose, a GPS (Global Positioning System) network of 650 stations distributed over Istanbul (Istanbul GPS Triangulation Network; abbreviated IGNA) covering the northern part of the North Anatolian Fault Zone (NAFZ) was established in 1997 and measured in 1999. From 1998 to 2004, the IGNA network was extended to 1888 stations covering an area of about 6000 km2, the whole administration area of Istanbul. All 1888 stations within the IGNA network were remeasured in 2005. In these two campaigns there existed 452 common points, and between these two campaigns two major earthquakes took place, on 17 August and 12 November 1999 with a Richter scale magnitude of 7.4 and 7.2, respectively. Several studies conducted for estimating the horizontal and vertical displacements as a result of these earthquakes on NAFZ are discussed in this paper. In geodynamic projects carried out before the earthquakes in 1999, an annual average velocity of 2–2.5 cm for the stations along the NAFZ were estimated. Studies carried out using GPS observations in the same area after these earthquakes indicated that point displacements vary depending on their distance to the epicentres of the earthquakes. But the directions of point displacements are similar. The results obtained through the analysis of the IGNA network also show that there is a common trend in the directions of point displacements in the study area. In this paper, the past studies about the tectonics of Marmara region are summarised and the results of the displacement analysis on the IGNA network are discussed.
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48

Bazanowski, Maciej, Anna Szostak-Chrzanowski, and Adam Chrzanowski. "Determination of GPS Session Duration in Ground Deformation Surveys in Mining Areas." Sustainability 11, no. 21 (November 3, 2019): 6127. http://dx.doi.org/10.3390/su11216127.

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Extraction of underground minerals causes subsidence of the ground surface due to gravitational forces. The subsidence rate depends on the type of extracted ore, as well as its shape, thickness, and depth. Additionally, the embedding and overburden rock properties influence the time needed for the deformations to reach the surface. Using the results of geodetic deformation monitoring, which supply the information on pattern and magnitude of surface deformation, the performance of the mine may be evaluated. The monitoring can supply information on the actual rock mass behaviour during the operation and in many cases during the years after the mining operations have ceased. Geodetic methods of deformation monitoring supply information on the absolute and relative displacements (changes in position in a selected coordinate system) from which displacement and strain fields for the monitored object may be derived. Thus, geodetic measurements provide global information on absolute and relative displacements over large areas, either at discrete points or continuous in the space domain. The geodetic methods are affected by errors caused by atmospheric refraction and delay of electromagnetic signal. Since geodetic measurements allow for redundancy and statistical evaluation of the quality of the data, they generally provide reliable results. Usually, the designed accuracy of deformation measurements should allow for the detection of at least one third of the expected maximum deformations over the desired time span at the 95% probability level. In ground subsidence studies in mining areas, 10 mm accuracy at 95% level in both vertical and horizontal displacements is typically required. In the case of salt mines, the process of ground subsidence in viscous rock is slow; therefore, subsidence monitoring surveys may be performed once a year. In subsidence determination, two techniques are commonly used: leveling and satellite positioning. The satellite positioning technique is used to determine the 3D (horizontal coordinates and height) or 2D position of monitored points (only horizontal coordinates). When comparing the heights determined from satellite and leveling surveys, it has to be noted that the leveling heights are referred with respect to the geoid (orthometric heights), while heights determined from satellite surveys are referred with respect to the ellipsoid (ellipsoidal height). In the case of satellite surveys, the accuracy of horizontal position is typically 2–3 times better than vertical. The analysis of the optimal session duration lead to the conclusion that in order to achieve the sub-cm accuracy of horizontal coordinates at 95% confidence level, the satellite positioning session length using Global Positioning System (GPS) should be at least three hours long. In order to achieve the sub-cm accuracy of height coordinate at 95% confidence level in a single observation session, the GPS session length should be at least twelve hours long.
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Nishimura, Sou, Masataka Ando, and Keiichi Tadokoro. "An application of numerical simulation techniques to improve the resolution of offshore fault kinematics using seafloor geodetic methods." Physics of the Earth and Planetary Interiors 151, no. 3-4 (August 2005): 181–93. http://dx.doi.org/10.1016/j.pepi.2005.03.002.

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50

Muszyński, Zbigniew, and Jarosław Rybak. "Application of Geodetic Measuring Methods for Reliable Evaluation of Static Load Test Results of Foundation Piles." Remote Sensing 13, no. 16 (August 5, 2021): 3082. http://dx.doi.org/10.3390/rs13163082.

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Abstract:
Geodetic measuring methods are widely used in the course of various geotechnical works. The main purpose is usually related to the location in space, geometrical dimensions, settlements, deflections, and other forms of displacements and their consequences. This study focuses on the application of selected surveying methods in static load tests (SLTs) of foundation piles. Basic aspects of the SLT are presented in the introductory section, together with the explanation of the authors’ motivation behind the novel (but already sufficiently tested) application of remote methods introduced to confirm, through inverse analysis, the load applied to the pile head under testing at every stage of its loading. Materials and methods are described in the second section in order to provide basic information on the test site and principles of the SLT method applied. The case study shows the methodology of displacement control in the particular test, which is described in light of a presented review of geodetic techniques for displacement control, especially terrestrial laser scanning and robotic tacheometry. The geotechnical testing procedure, which is of secondary importance for the current study, is also introduced in order to emphasize the versatility of the proposed method. Special attention is paid to inverse analysis (controlling of the pile loading force on the basis of measured deflections, and static calculations by means of standard structural analysis and the finite element method (FEM)) as a tool to raise the credibility of the obtained SLT results. The present case study from just one SLT, instrumented with various geodetic instrumentation, shows the results of a real-world dimensions test. The obtained variability of the loading force within a range of 15% (depending on real beam stiffness) proves good prospects for the application of the proposed idea in practice. The results are discussed mainly in light of the previous authors’ experience with the application of remote techniques for reliable displacement control. As only a few references could be found (mainly by private communication), both the prospects for new developments using faster and more accurate instruments as well as the need for the validation of these findings on a larger number of SLTs (with a very precise definition of beam stiffness) are underlined in the final remarks.
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