scholarly journals Robust Estimators in Geodetic Networks Based on a New Metaheuristic: Independent Vortices Search

Sensors ◽  
2019 ◽  
Vol 19 (20) ◽  
pp. 4535 ◽  
Author(s):  
Ismael Érique Koch ◽  
Ivandro Klein ◽  
Luiz Gonzaga ◽  
Marcelo Tomio Matsuoka ◽  
Vinicius Francisco Rofatto ◽  
...  
Keyword(s):  
Large Scale ◽  
Three Dimensional ◽  
Search Space ◽  
Global Navigation Satellite Systems ◽  
Robust Estimator ◽  
Satellite Systems ◽  
Original Algorithm ◽  
Geodetic Networks ◽  
Global Navigation Satellite ◽  
Better Than

Geodetic networks provide accurate three-dimensional control points for mapping activities, geoinformation, and infrastructure works. Accurate computation and adjustment are necessary, as all data collection is vulnerable to outliers. Applying a Least Squares (LS) process can lead to inaccuracy over many points in such conditions. Robust Estimator (RE) methods are less sensitive to outliers and provide an alternative to conventional LS. To solve the RE functions, we propose a new metaheuristic (MH), based on the Vortex Search (IVS) algorithm, along with a novel search space definition scheme. Numerous scenarios for a Global Navigation Satellite Systems (GNSS)-based network are generated to compare and analyze the behavior of several known REs. A classic iterative RE and an LS process are also tested for comparison. We analyze the median and trim position of several estimators, in order to verify their impact on the estimates. The tests show that IVS performs better than the original algorithm; therefore, we adopted it in all subsequent RE computations. Regarding network adjustments, outcomes in the parameter estimation show that REs achieve better results in large-scale outliers’ scenarios. For detection, both LS and REs identify most outliers in schemes with large outliers.

scholarly journals Adjustment of an Integrated Geodetic Network Composed of GNSS Vectors and Classical Terrestrial Linear Pseudo-Observations

2021 ◽  
Vol 11 (10) ◽  
pp. 4352
Author(s):  
Tadeusz Gargula
Keyword(s):  
Three Dimensional ◽  
Geodetic Network ◽  
Global Navigation Satellite Systems ◽  
Adjustment Process ◽  
Dimensional System ◽  
Integrated Network ◽  
Satellite Systems ◽  
Linear Distance ◽  
Easy Integration ◽  
Global Navigation Satellite

The paper proposes a new method for adjusting classical terrestrial observations (total station) together with satellite (GNSS-Global Navigation Satellite Systems) vectors. All the observations are adjusted in a single common three-dimensional system of reference. The proposed method does not require the observations to be projected onto an ellipsoid or converted between reference systems. The adjustment process follows the transformation of a classical geodetic network (distances and horizontal and vertical angles) into a spatial linear (distance) network. This step facilitates easy integration with GNSS vectors when results are numerically processed. The paper offers detailed formulas for calculating pseudo-observations (spatial distances) from input terrestrial observations (horizontal and vertical angles, horizontal distances, height of instrument and height of target). The next stage was to set observation equations and transform them into a linear form (functional adjustment model of geodetic observations). A method was provided as well for determining the mean errors of the pseudo-observations, necessary to assess the accuracy of the values following the adjustment (point coordinates). The proposed algorithm was verified in practice whereby an integrated network made up of a GNSS vector network and a classical linear-angular network was adjusted.

scholarly journals A New Acquisition Algorithm with Elimination Side Peak for All BOC Signals

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Fang Liu ◽  
Yongxin Feng
Keyword(s):  
Correlation Function ◽  
Global Navigation Satellite Systems ◽  
Navigation Satellite ◽  
Binary Offset Carrier ◽  
Side Peak ◽  
Acquisition Performance ◽  
Satellite Systems ◽  
Simulation Results ◽  
Global Navigation Satellite ◽  
Better Than

A new inhibition side peak acquisition (ISPA) algorithm is proposed for binary offset carrier (BOC) modulated signals, which will be utilized in global navigation satellite systems (GNSS). We eliminate all side peaks of the BOC correlation function (CF) by structuring special sequences composed of PRN code and cycle rectangular sequences. The new algorithm can be applied to both generic sine- and cosine-phased BOC signals, as well as to all modulation orders. Theoretical and simulation results demonstrate that the new algorithm can completely eliminate the ambiguity threat in the acquisition process, and it can adapt to lower SNR. In addition, this algorithm is better than the traditional algorithms in acquisition performance and inhibition side peak ability.

scholarly journals The contribution of engineering surveys by means of GPS to the determination of crustal movements in Istanbul

2011 ◽  
Vol 11 (6) ◽  
pp. 1705-1713 ◽  
Author(s):  
M. Özyaşar ◽  
M. T. Özlüdemir
Keyword(s):  
Positional Information ◽  
Global Navigation Satellite Systems ◽  
Marmara Region ◽  
Satellite Systems ◽  
Geodetic Networks ◽  
The North ◽  
Richter Scale ◽  
Tectonically Active ◽  
Vertical Displacements ◽  
Global Navigation Satellite

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.

Bit Sign Transition Cancellation Method for GNSS Signal Acquisition

2011 ◽  
Vol 65 (1) ◽  
pp. 73-97 ◽  
Author(s):  
Kewen Sun ◽  
Letizia Lo Presti
Keyword(s):  
Doppler Shift ◽  
Signal To Noise Ratio ◽  
Search Space ◽  
Global Navigation Satellite Systems ◽  
Main Peak ◽  
Signal Acquisition ◽  
Satellite Systems ◽  
Gps Modernization ◽  
Improved Performance ◽  
Global Navigation Satellite

The next generation Global Navigation Satellite Systems (GNSS), such as Galileo and Global Positioning System (GPS) modernization, will use signals with equal code and bit periods, resulting in a potential bit sign transition in each primary code period of the received signal segments. A bit sign transition occurring within an integration period usually causes a splitting of the Cross Ambiguity Function (CAF) main peak into two smaller side lobes along the Doppler shift axis in the search space and it may lead to an incorrect Doppler shift estimate, which results in a serious performance degradation of the acquisition system. This paper proposes a novel two steps based bit sign transition cancellation method which can overcome the bit sign transition problem and remove or mitigate the CAF peak splitting impairments. The performance of the proposed technique has been comprehensively evaluated with Monte Carlo simulations in terms of detection and false alarm probabilities, which are presented by Receiver Operating Characteristic (ROC) and Signal-to-Noise-Ratio (SNR) curves. The test results show that the proposed acquisition technique can provide improved performance in comparison with the state-of-the-art acquisition approaches.

scholarly journals Intelligent Urban Positioning: Integration of Shadow Matching with 3D-Mapping-Aided GNSS Ranging

2017 ◽  
Vol 71 (1) ◽  
pp. 1-20 ◽  
Author(s):  
Mounir Adjrad ◽  
Paul D. Groves
Keyword(s):  
Urban Areas ◽  
Three Dimensional ◽  
Covariance Matrices ◽  
Global Navigation Satellite Systems ◽  
3D Mapping ◽  
Deterministic Approach ◽  
Satellite Systems ◽  
Gnss Positioning ◽  
Error Covariance ◽  
Global Navigation Satellite

In dense urban areas, conventional Global Navigation Satellite Systems (GNSS) positioning can exhibit errors of tens of metres due to the obstruction and reflection of the signals by the surrounding buildings. By using Three-Dimensional (3D) mapping of the buildings, the accuracy can be significantly improved. This paper demonstrates the first integration of GNSS shadow matching with 3D-mapping-aided GNSS ranging. The integration is performed in the position domain, whereby separate ranging and shadow matching position solutions are computed, then combined using direction-dependent weighting. Two weighting strategies are compared, one based on the computation of ranging-based and shadow matching position error covariance matrices, and a deterministic approach based on the street azimuth. Using experimental data collected from a u-blox GNSS receiver, it is shown that both integrated position solutions are significantly more accurate than either shadow matching or 3D-mapping-aided ranging on their own. The overall Root Mean Square (RMS) horizontal accuracy obtained using covariance-based weighting was 6·1 m, a factor of four improvement on the 25·9 m obtained using conventional GNSS positioning. Results are also presented using smartphone data, where shadow matching is integrated with conventional GNSS positioning.

scholarly journals Three-dimensional data assimilation for ionospheric reference scenarios

2017 ◽  
Vol 35 (2) ◽  
pp. 203-215 ◽  
Author(s):  
Tatjana Gerzen ◽  
Volker Wilken ◽  
David Minkwitz ◽  
Mainul M. Hoque ◽  
Stefan Schlüter
Keyword(s):  
Data Assimilation ◽  
Three Dimensional ◽  
Model Space ◽  
Initial Guess ◽  
Global Navigation Satellite Systems ◽  
Background Model ◽  
Electron Content ◽  
Total Electron ◽  
Satellite Systems ◽  
Global Navigation Satellite

Abstract. The reliable estimation of ionospheric refraction effects is an important topic in the GNSS (Global Navigation Satellite Systems) positioning and navigation domain, especially in safety-of-life applications. This paper describes a three-dimensional ionosphere reconstruction approach that combines three data sources with an ionospheric background model: space- and ground-based total electron content (TEC) measurements and ionosonde observations. First the background model is adjusted by F2 layer characteristics, obtained from space-based ionospheric radio occultation (IRO) profiles and ionosonde data, and secondly the final electron density distribution is estimated by an algebraic reconstruction technique.The method described is validated by TEC measurements of independent ground-based GNSS stations, space-based TEC from the Jason 1 and 2 satellites, and ionosonde observations. A significant improvement is achieved by the data assimilation, with a decrease in the residual errors by up to 98 % compared to the initial guess of the background. Furthermore, the results underpin the capability of space-based measurements to overcome data gaps in reconstruction areas where less GNSS ground-station infrastructure exists.

scholarly journals Methods for studying the morphology of abrasion-accumulative coast of the West coast of the Crimea using UAV and GNSS (on the example of a land of the territory of Great Sevastopol)

2021 ◽  
Vol 27 (1) ◽  
pp. 351-363
Author(s):  
Aleksandr Suchilin ◽  
Nadezhda Belay ◽  
Ivan Voskresensky ◽  
Svetlana Mikheeva ◽  
Victoria Zorina ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Large Scale ◽  
Geodetic Network ◽  
Field Studies ◽  
Research Area ◽  
Global Navigation Satellite Systems ◽  
The Black Sea ◽  
Western Coast ◽  
Satellite Systems ◽  
Global Navigation Satellite

The method of studying the abrasion-accumulative coast of the Western coast of Crimea within the urban area of Sevastopol includes remote sensing using unmanned aerial vehicles (UAVs) and field studies of the morphology and structure of abrasion and landslide landforms of the coast. As a result of the research, the morphological zoning of the abrasion-accumulative coast was established. The formation of the morphological zoning of the abrasion-accumulative coast (according to I.S. Shchukin) during the last 150 years took place at a constant level of the Black Sea. Analysis of the coast from previously published multi-temporal maps and aerospace photographs revealed different stages in the movement of the coastline and landslide scarp. Since 1966, the coastal area has been used for low-rise residential development, which may have influenced the activity of landslide processes in the coastal strip. Remote sensing using UAVs consists of aerial photography of the research area along the planned flight route at altitudes of 20–100 m, with further compilation of a large-scale orthophotomap from a mosaic of images with geospatial fixation of images to the signs of the reference long-term local geodetic network, previously measured by the methods of global navigation satellite systems (GNSS ), as well as the formation of a digital elevation model (DEM) and the compilation of derived maps and plans on its basis in the environment of geographic information systems (GIS), for the analysis of the morphometry of the relief and modeling. The developed method of remote sensing of the Earth with the use of UAVs and simultaneous field studies makes it possible to organize operational monitoring of dynamically developing abrasion-accumulative shores.

scholarly journals Dual-parameter regularization method in three-dimensional ionospheric reconstruction

2018 ◽  
Vol 36 (5) ◽  
pp. 1255-1266
Author(s):  
Sicheng Wang ◽  
Sixun Huang ◽  
Hanxian Fang
Keyword(s):  
Regularization Method ◽  
Three Dimensional ◽  
Global Navigation Satellite Systems ◽  
Electron Content ◽  
Regularization Algorithm ◽  
Total Electron ◽  
Satellite Systems ◽  
Regularization Parameters ◽  
Global Navigation Satellite ◽  
Parameter Regularization

Abstract. Ionospheric tomography based on the total electron content (TEC) data along the ray path from Global Navigation Satellite Systems (GNSS) satellites to ground receivers is a typical ill-posed inverse problem. The regularization method is an effective method to solve this problem, which incorporates prior constraints to approximate the real ionospheric variations. When two or more prior constraints are used, the corresponding multiple regularization parameters are introduced in the cost functional. Assuming that the ionospheric spatial variations can be separable in the horizontal and vertical directions, different prior constraints are used in each direction, and the dual-parameter regularization algorithm is established to reconstruct the three-dimensional ionospheric electron density in the present paper. To make the reconstruction results comprehensively reflect the observation information and background (prior) information, it is crucial to determine the optimal regularization parameters. The linear model function method is used to choose these regularization parameters. Both an ideal test and a real test show that this regularization algorithm can effectively improve the background model output.

scholarly journals Software-Defined Radio Technologies for GNSS Receivers: A Tutorial Approach to a Simple Design and Implementation

2011 ◽  
Vol 2011 ◽  
pp. 1-27 ◽  
Author(s):  
Fabio Principe ◽  
Giacomo Bacci ◽  
Filippo Giannetti ◽  
Marco Luise
Keyword(s):  
Software Defined Radio ◽  
Global Navigation Satellite Systems ◽  
Satellite Systems ◽  
Gnss Receivers ◽  
Software Receivers ◽  
Global Navigation Satellite ◽  
Architecture And Design ◽  
General Architecture ◽  
Configurable Architecture ◽  
Better Than

The field of satellite navigation has witnessed the advent of a number of new systems and technologies: after the landmark design and development of the Global Positioning System (GPS), a number of new independent Global Navigation Satellite Systems (GNSSs) were or are being developed all over the world: Russia's GLONASS, Europe's GALILEO, and China's BEIDOU-2, to mention a few. In this ever-changing context, the availability of reliable and flexible receivers is becoming a priority for a host of applications, including research, commercial, civil, and military. Flexible means here both easily upgradeable for future needs and/or on-the-fly reprogrammable to adapt to different signal formats. An effective approach to meet these design goals is the software-defined radio (SDR) paradigm. In the last few years, the availability of new processors with high computational power enabled the development of (fully) software receivers whose performance is comparable to or better than that of conventional hardware devices, while providing all the advantages of a flexible and fully configurable architecture. The aim of this tutorial paper is surveying the issue of the general architecture and design rules of a GNSS software receiver, through a comprehensive discussion of some techniques and algorithms, typically applied in simple PC-based receiver implementations.

“After 300 meters turn right” – the future of Russia’s GLONASS and the development of global satellite navigation systems

foresight ◽  
2014 ◽  
Vol 16 (5) ◽  
pp. 448-461 ◽  
Author(s):  
Mikhail B. Bokov ◽  
Anastasia Edelkina ◽  
Marina Klubova ◽  
Thomas Thurner ◽  
Natalia P. Velikanova ◽  
...  
Keyword(s):  
Large Scale ◽  
Global Navigation Satellite Systems ◽  
Navigation Systems ◽  
Niche Markets ◽  
Content Type ◽  
Satellite Systems ◽  
The Future ◽  
Comprehensive Picture ◽  
Satellite Navigation Systems ◽  
Global Navigation Satellite

Purpose – Global navigation satellite systems (GNSS) were designed to determine the exact location of objects on land, water and air for military purposes. With the opening of the satellite signal for civilian use, the technology created business opportunities for various applications. Today, satellite positioning technology is used by transporters, carriers, motorists, surveyors, builders, foresters, etc. through a wide array of devices like mobile phones or multimedia devices with built-in receiver modules. Design/methodology/approach – This paper provides the results of a recently held foresight exercise on the future development of Russia’s GLONASS system. Findings – The foresight exercise suggested a number niche markets where the GLONASS technology could be of great use, like monitoring of buildings and construction sides or the monitoring of shipments. In addition, in the case of Russia, large-scale government-driven investment programs will be key drivers for GLONASS’ growth perspectives. Originality/value – The paper provides a comprehensive picture of the development of GNSS for civilian use until 2020.

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