GPS Satellite Surveying — Practical Aspects

1984 ◽  
Vol 38 (3) ◽  
pp. 177-192 ◽  
Author(s):  
Larry D. Hothem ◽  
Clyde C. Goad ◽  
Benjamin W. Remondi
Keyword(s):  
Three Dimensional ◽  
Field Tests ◽  
Geodetic Survey ◽  
National Geodetic Survey ◽  
Extensive Experience ◽  
Global Positioning ◽  
Position Data ◽  
Survey System ◽  
And Storage ◽  
Processing Steps

No satellite-based survey system has gained as much attention and interest as the Global Positioning System (GPS). Establishing precise positions by use of the GPS is rapidly becoming a powerful and economical tool for surveyors. The extensive experience gained at the National Geodetic Survey (NGS), from field tests in March 1983 to operational projects performed later in 1983 and early 1984, has demonstrated that observations of the GPS satellite signals yield very accurate three-dimensional relative position data. Baselines of up to 100 km are routinely measured to accuracies of 1 cm to 5 cm rms. Differential ellipsoid height accuracies at the few centimeter level have been achieved; depending on accuracies of geoidal undulations, useful elevation differences can be computed. This paper focuses on the more mundane activities required to obtain such results. Although GPS satellite surveying employs sophisticated methodology and instrumentation, there are many practical aspects to be considered. These include requirements for ties to existing control, station selection criteria, field procedures, data handling and storage, and processing steps.

scholarly journals Seeking a Reference Frame for Cartographic Sonification

2018 ◽  
Author(s):  
Megen Brittell
Keyword(s):  
Dimensional Space ◽  
Three Dimensional ◽  
Visual Display ◽  
Data Cube ◽  
Geospatial Data ◽  
Data Sets ◽  
Extensive Experience ◽  
Map Design ◽  
Position Data ◽  
New Perspective

Sonification of geospatial data must situate data values in two (or three) dimensional space. The need to position data values in space distinguishes geospatial data from other multi-dimensional data sets. While cartographers have extensive experience preparing geospatial data for visual display, the use of sonification is less common. Beyond availability of tools or visual bias, an incomplete understanding of the implications of parameter mappings that cross conceptual data categories limits the application of sonification to geospatial data. To catalyze the use of audio in cartography, this paper explores existing examples of parameter mapping sonification through the framework of the geographic data cube. More widespread adoption of auditory displays would diversify map design techniques, enhance accessibility of geospatial data, and may also provide new perspective for application to non-geospatial data sets.

scholarly journals A INFLUÊNCIA DOS PARÂMETROS DE CALIBRAÇÃO DE ANTENAS GPS NAS ALTITUDES ELIPSOIDAIS NO POSICIONAMENTO RELATIVO ESTÁTICO

2015 ◽  
Vol 21 (3) ◽  
pp. 532-547
Author(s):  
Renata Magda Cavalcante Werlich ◽  
Claudia Pereira Krueger ◽  
Günter Schmitt
Keyword(s):  
Global Positioning System ◽  
Geodetic Survey ◽  
National Geodetic Survey ◽  
Positioning System ◽  
Phase Center ◽  
Global Positioning ◽  
Phase Center Variation ◽  
America Latina

Resumo:Alta acurácia em posicionamento GPS (Global Positioning System) é obtida através da eliminação parcial ou total dos erros presentes nas observações, particularmente os sistemáticos. Um deles é o erro de centro de fase da antena GPS. Ele é diretamente dependente da antena utilizada, visto que cada uma delas tem suas características próprias de construção e recepção do sinal GPS. Portanto, é de extrema importância o conhecimento individual do centro de fase da antena (Phase Center Offset- Phase Center Variation). Entre outros, existem parâmetros fornecidos pelo NGS (National Geodetic Survey), no entanto, esses valores são médios e não são valores próprios das antenas usadas nos posicionamentos GPS. Os parâmetros individuais das antenas, neste trabalho, foram fornecidos pela BCAL/UFPR (Base de Calibração de Antenas GNSS na UFPR). Realizaram-se posicionamentos GPS em 9 (nove) pontos. Estes foram distribuidos em 3 (três) grupos de linhas de base (9km, 45km e 105km). Para cada comprimento de linha de base os rastreios GPS seguiram simultâneos aplicando o Método de Posicionamento Relativo Estático, com um intervalo de gravação de dados de 15 segundos e máscara de elevação de 15°. Foram encontradas diferenças na comparação das altitudes elipsoidais e no comprimento das linhas de bases, quando não se utilizou parâmetros, na ordem do centímetro. De fato, os valores obtidos da BCAL/UFPR são provenientes da utilização dos próprios equipamentos, desta forma, fiéis às antenas utilizadas, enquanto que os fornecidos pelo NGS são valores médios. Destaca-se que a BCAL/UFPR é a primeira base de calibração de antenas GPS/GLONASS no Brasil e na América Latina

Ultrasonographic 3D Evaluation in the Diagnosis of Bladder Endometriosis: A Prospective Comparative Diagnostic Accuracy Study

2021 ◽  
pp. 1-8
Author(s):  
Fabio Barra ◽  
Franco Alessandri ◽  
Carolina Scala ◽  
Simone Ferrero
Keyword(s):  
Diagnostic Accuracy ◽  
Three Dimensional ◽  
3D Ultrasound ◽  
Diagnostic Accuracy Study ◽  
Extensive Experience ◽  
Deep Endometriosis ◽  
3D Reconstructions ◽  
Analysis Group ◽  
Bladder Endometriosis ◽  
Accuracy Study

<b><i>Objective:</i></b> The use of three-dimensional (3D) transvaginal ultrasonography (TVS) has been investigated for the diagnosis of deep endometriosis (DE). This study aimed to evaluate if 3D reconstructions improve the performance of TVS) in assessing the presence and characteristics of bladder endometriosis (BE). <b><i>Design:</i></b> This was a single-center comparative diagnostic accuracy study. <b><i>Participants/Materials, Setting, Methods:</i></b> Patients referred to our institution (Piazza della Vittoria 14 Srl, Genova, Italy) with clinical suspicion of DE were included. In case of surgery, women underwent systematic preoperative ultrasonographic imaging; an experienced sonographer performed a conventional TVS; another experienced sonographer, blinded to results of the previous exam, performed TVS, with the addition of 3D modality. The presence and characteristics of BE nodules were described in accord with International DE Analysis group consensus. Ultrasound data were compared with surgical and histological results. <b><i>Results:</i></b> Overall, BE was intraoperatively found in 34 out of 194 women who underwent surgery for DE (17.5%; 95% confidence interval: 12.8–23.5%). TVS without and with 3D reconstructions were able to detect endometriotic BE in 82.2% (<i>n</i> = 28/34) and 85.3% (<i>n</i> = 29/34) of the cases (<i>p</i> = 0.125). Both the exams similarly estimated the largest diameter of BE (<i>p</i> = 0.652) and the distance between the endometriotic nodule and the closest ureteral meatus (<i>p</i> = 0.341). However, TVS with 3D reconstructions was more precise in estimating the volume of BE (<i>p</i> = 0.031). In one case (2.9%), TVS without and with 3D reconstructions detected the infiltration of the intramural ureter, which was confirmed at surgery and required laparoscopic ureterovesical reimplantation. <b><i>Limitations:</i></b> The extensive experience of the gynecologists performing the ultrasonographic scans, the lack of prestudy power analysis, and the population selected, which may have been influenced by the position of the institution as a referral center specialized in the treatment of severe endometriosis, are limitations of the current study. <b><i>Conclusion:</i></b> Our results demonstrated the high accuracy of ultrasound for diagnosing BE. The addition of 3D reconstructions does not improve the performance of TVS in diagnosing the presence and characteristics of BE. However, the volume of BE may be more precisely assessed by 3D ultrasound.

scholarly journals Hydrothermal Synthesis and Structural Investigation of a Crystalline Uranyl Borosilicate

Inorganics ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 25
Author(s):  
Kristen A. Pace ◽  
Vladislav V. Klepov ◽  
Mark D. Smith ◽  
Travis Williams ◽  
Gregory Morrison ◽  
...  
Keyword(s):  
Synthesis Method ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Exploratory Research ◽  
The Novel ◽  
Orthorhombic Space Group ◽  
Crystalline Materials ◽  
Waste Remediation ◽  
And Storage ◽  
X Ray Absorption

The relevance of multidimensional and porous crystalline materials to nuclear waste remediation and storage applications has motivated exploratory research focused on materials discovery of compounds, such as actinide mixed-oxoanion phases, which exhibit rich structural chemistry. The novel phase K1.8Na1.2[(UO2)BSi4O12] has been synthesized using hydrothermal methods, representing the first example of a uranyl borosilicate. The three-dimensional structure crystallizes in the orthorhombic space group Cmce with lattice parameters a = 15.5471(19) Å, b = 14.3403(17) Å, c = 11.7315(15) Å, and V = 2615.5(6) Å3, and is composed of UO6 octahedra linked by [BSi4O12]5− chains to form a [(UO2)BSi4O12]3− framework. The synthesis method, structure, results of Raman, IR, and X-ray absorption spectroscopy, and thermal stability are discussed.

Digital transformation of the educational and methodological support of the railway university

2021 ◽  
Vol 2 (4) ◽  
pp. 427-434
Author(s):  
E. V. Boikov ◽  
A. I. Orlenko ◽  
S. V. Domnin
Keyword(s):  
Training Programs ◽  
Three Dimensional ◽  
Educational Process ◽  
Learning System ◽  
Interactive Training ◽  
Distance Learning System ◽  
Processing Information ◽  
Processing And Storage ◽  
Independent Work ◽  
And Storage

A full-fledged transformation is impossible without the use of new didactic approaches and without the creation of a qualitatively new educational and methodological support. This is due to the peculiarities of the modern student. Modern students were born and grew up in an information-saturated world and they are dominated by clip thinking, which is focused on processing information in short portions. Based on this, the problem of developing such training programs that would be aimed at independent work, based on game methods of presenting information, would take into account the psychophysiological features of perception, processing and storage of information by a modern person becomes urgent.To solve this problem, the authors analyzed the results of cognitive psychology research, conducted a self-analysis of the experience of developing and implementing three-dimensional interactive training programs in the educational process.The paper reveals the problems and disadvantages of traditional ways of presenting information. Examples of the implementation of interactive training applications are shown. The method of organizing a distributed distance learning system is presented.The conducted research allowed us to outline ways to modernize educational and methodological support by using interactive applications, mobile learning, resource allocation, introduction of modern digital solutions and creation of a comfortable educational environment.

Multi-GNSS Single-Difference Baseline Processing at NGS with newly developed M-PAGES software

2021 ◽  
Author(s):  
Bryan Stressler ◽  
Andria Bilich ◽  
Clement Ogaja ◽  
Jacob Heck
Keyword(s):  
Geodetic Survey ◽  
Integer Ambiguity ◽  
National Geodetic Survey ◽  
Processing Strategy ◽  
Dual Frequency ◽  
Software Suite ◽  
Legacy Software ◽  
Double Differences ◽  
Single Difference ◽  
Gps Observations

&lt;p&gt;The U.S. National Geodetic Survey (NGS) has historically processed dual-frequency GPS observations in a double-differenced mode using the legacy software called the Program for the Adjustment of GPS Ephemerides (PAGES). As part of NGS&amp;#8217; modernization efforts, a new software suite named M-PAGES (i.e., Multi-GNSS PAGES) is being developed to replace PAGES. M-PAGES consists of a suite of C++ and Python libraries, programs, and scripts built to process observations from all GNSS constellations. The M-PAGES team has developed a single-difference baseline processing strategy that is suitable for multi-GNSS. This approach avoids the difficulty of forming double-differences across systems or frequencies, which may inhibit integer ambiguity resolution. The M-PAGES suite is expected to deploy to NGS&amp;#8217; Online Positioning User Service (OPUS) later this year. Here, we present the processing strategy being implemented along with a performance evaluation from sample baseline solutions obtained from data collected within the NOAA CORS Network.&lt;/p&gt;

A Method for the Evaluation of Vertical Crustal Movement from Scattered Geodetic Relevellings

1974 ◽  
Vol 11 (5) ◽  
pp. 605-610 ◽  
Author(s):  
P. Vaníček ◽  
D. Christodulidis
Keyword(s):  
Chesapeake Bay ◽  
Statistical Significance ◽  
Geodetic Survey ◽  
National Geodetic Survey ◽  
Specific Level ◽  
Vertical Crustal Movement ◽  
Crustal Movements ◽  
Velocity Surface ◽  
Vertical Crustal Movements ◽  
The U.S

The existing techniques for the quantitative evaluation of vertical crustal movements from geodetic spirit levelling have one common feature. They can deal only with a complete network of systematically relevelled connected lines. This paper presents a method, based on the least-squares fitting of a velocity surface, capable of using scattered as well as connected relevelled segments. A facility to choose a specific level of statistical significance of the results is built in. The performance of the method is tested on data for the vicinity of Chesapeake Bay. The results compare well with those of the U.S. National Geodetic Survey.

STATIC AND DYNAMIC PERFORMANCE EVALUATION OF A PRE-STRESSED CONCRETE BRIDGE THROUGH FIELD TESTING AND MONITORING

2009 ◽  
Vol 09 (04) ◽  
pp. 711-728 ◽  
Author(s):  
C. S. CAI ◽  
M. ARAUJO ◽  
A. NAIR ◽  
X. SHI
Keyword(s):  
Quantitative Methods ◽  
Dynamic Performance ◽  
Three Dimensional ◽  
Field Tests ◽  
Field Measurements ◽  
Field Testing ◽  
Concrete Bridge ◽  
Bridge Structures ◽  
Dimensional Finite Element ◽  
Three Dimensional Finite Element

This paper presents field tests performed on a slab-on-girder pre-stressed concrete bridge. The bridge was tested under static loading, crawling loading, and dynamic loading. A full three-dimensional finite element prediction under both static and dynamic loadings was carried out and the results were compared with the field measurements. While acoustic emission (AE) monitoring of bridge structures is not a new vista, the method has not been fully exploited in bridge monitoring. Though numerous quantitative methods have been proposed, they have not yet developed to be useful for actual field tests of bridges. Therefore, in this study, an attempt was made to use the intensity analysis technique for damage quantification using the AE method.

The experimental geoid 2020 – the first joint geoid model for the North American and Pacific Geopotential Datum 

2021 ◽  
Author(s):  
Yan Ming Wang ◽  
Xiaopeng Li ◽  
Kevin Ahlgren ◽  
Jordan Krcmaric ◽  
Ryan Hardy ◽  
...  
Keyword(s):  
North American ◽  
Gravity Data ◽  
The United States ◽  
Geodetic Survey ◽  
Airborne Gravity ◽  
Data Sets ◽  
National Geodetic Survey ◽  
Geoid Model ◽  
Satellite Gravity ◽  
The North

&lt;p&gt;For the upcoming North American-Pacific Geopotential Datum of 2022, the National Geodetic Survey (NGS), the Canadian Geodetic Survey (CGS) and the&amp;#160;National Institute of Statistics and Geography of Mexico (INEGI) computed the first joint experimental gravimetric geoid model (xGEOID) on 1&amp;#8217;x1&amp;#8217; grids that covers a region bordered by latitude 0 to 85 degree, longitude 180 to 350 degree east.&amp;#160;xGEOID20 models are computed using terrestrial gravity data, the latest satellite gravity model GOCO06S, altimetric gravity data DTU15, and an additional nine airborne gravity blocks of the GRAV-D project, for a total of 63 blocks. In addition, a digital elevation model in a 3&amp;#8221; grid was produced by combining MERIT, TanDEM-X, and USGS-NED and used for the topographic/gravimetric reductions. The geoid models computed from the height anomalies (NGS) and from the Helmert-Stokes scheme (CGS) were combined using two different weighting schemes, then evaluated against the independent GPS/leveling data sets. The models perform in a very similar way, and the geoid comparisons with the most accurate Geoid Slope Validation Surveys (GSVS) from 2011, 2014 and 2017 indicate that the&amp;#160;relative geoid accuracy&amp;#160;could be around 1-2 cm baseline lengths up to 300 km for these GSVS lines in the United States. The xGEOID20 A/B models were selected from the combined models based on the validation results. The geoid accuracies were also estimated using the forward modeling.&lt;/p&gt;

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