Author: John F. Raquet
Publisher:
ISBN: 9781423554561
Category : Global Positioning System
Languages : en
Pages : 282
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Book Description
To perform the most precise relative positioning using GPS, it is necessary to resolve the carrier-phase integer cycle ambiguities. This process becomes increasingly difficult as the distance between the mobile and reference GPS receivers increases, due to the decorrelation of the GPS errors with distance, resulting in a practical limit on the distance over which ambiguity resolution can be performed when using a single reference receiver. This thesis proposes a novel method, called NetAdjust, which uses multiple reference receivers to reduce code and carrier-phase differential measurement errors and improve the ability to resolve carrier-phase ambiguities. The NetAdjust method is based upon an optimal linear minimum error variance estimator, and it "encapsulates" all of the network information into the measurements of a single reference receiver, so standard single-reference differential GPS processing algorithms can be used. The geometry of the reference receiver network is embedded within the error covariance matrix, and a functional form of this covariance matrix is described. The NetAdjust method was tested using two different GPS networks, an 11-receiver network covering a 400 km x 600 km region in southern Norway, and a 4-receiver network covering a 50 km x 150 km region at Holloman AFB in New Mexico. The results for L1 code, L1 phase, and widelane phase measurements are analyzed in the measurement domain and the position domain, showing improvements in RMS errors of up to 50% when using NetAdjust. Significant improvements in the ability to resolve carrier-phase ambiguities are also demonstrated for the Holloman and Norway test networks. Issues relating to development of an operational, real-time NetAdjust system are discussed. Also, a covariance analysis method is developed which can be used to predict NetAdjust effectiveness under various conditions and network configurations.
Author: John Foster Raquet
Publisher:
ISBN:
Category : Global Positioning System
Languages : en
Pages : 259
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Book Description
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Author: Brian L. Bracy
Publisher:
ISBN: 9781423535768
Category :
Languages : en
Pages : 77
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Book Description
New applications for GPS have driven a demand for increased positioning accuracy. The emerging GPS technology particularly affects the test community. The testing equipment and method must provide a solution that is an order of magnitude more precise than the tested equipment to achieve the desired accuracy. Carrier-phase differential GPS methods using a network of reference receivers can provide the centimeter-level accuracy required over a large geographical area. This thesis evaluates the performance of a 5-receiver network over a 50 km x 120 km area of New Mexico, using a GPS network algorithm called NetAdjust. The percentage of time a fixed integer solution was available for a kinematic baseline was investigated for three types of measurements. Results showed that the virtual reference receiver method using NetAdjust-corrected measurements outperformed the raw and NetAdjust-corrected file results. However, these results were only obtained for the shortest baseline receivers. The receivers with longer baselines did not experience the same degree of success, but did lead to several important insights gained from the research. Most importantly, the accuracy of the reference receiver coordinates is critical to the performance of a reference receiver network. Further testing must be accomplished before a full implementation is recommended.
Author: Brian Bracy (L.)
Publisher:
ISBN:
Category : Artificial satellites in navigation
Languages : en
Pages : 154
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Book Description
Author: Paul E. Henderson
Publisher:
ISBN: 9781423528678
Category : Global Positioning System
Languages : en
Pages : 164
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Book Description
The most precise relative positioning obtained using differential GPS depends on accurately determining carrier-phase integer ambiguities. To achieve high precision, many current static and kinematic algorithms use a floating- point solution until enough information becomes available to fix the carrier- phase ambiguities accurately. A mew method is presented that uses a multiple model Kalman filter to resolve the carrier-phase integer ambiguities. This method starts with the floating-point results, yet smoothly and rapidly attains the precision of the correct fixed-integer solution, eliminating the need to decide when to switch from the floating to the fixed-integer solution. This method is based on a theoretically correct blending of solutions from multiple filters. This new technique is computationally efficient, providing a robust navigation solution useful in demanding applications such as precision landing and autonomous navigation. The new method was evaluated during static ground and flight tests. Initial results indicate that the new method is capable of quickly resolving the carrier-phase ambiguities and provides a highly accurate (centimeter-level) navigation solution. However, the performance of the new method depends on the correct carrier-phase ambiguity set being hypothesized by one of the multiple filters. Recommendations for further research are included.
Author: Jaewoo Jung
Publisher:
ISBN:
Category :
Languages : en
Pages : 172
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Book Description
Author: Guochang Xu
Publisher: Springer
ISBN: 3662503670
Category : Science
Languages : en
Pages : 508
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Book Description
This reference and handbook describes theory, algorithms and applications of the Global Positioning System (GPS/Glonass/Galileo/Compass). It is primarily based on source-code descriptions of the KSGsoft program developed at the GFZ in Potsdam. The theory and algorithms are extended and verified for a new development of a multi-functional GPS/Galileo software. Besides the concepts such as the unified GPS data processing method, the diagonalisation algorithm, the adaptive Kalman filter, the general ambiguity search criteria, and the algebraic solution of variation equation reported in the first edition, the equivalence theorem of the GPS algorithms, the independent parameterisation method, and the alternative solar radiation model reported in the second edition, the modernisation of the GNSS system, the new development of the theory and algorithms, and research in broad applications are supplemented in this new edition. Mathematically rigorous, the book begins with the introduction, the basics of coordinate and time systems and satellite orbits, as well as GPS observables, and deals with topics such as physical influences, observation equations and their parameterisation, adjustment and filtering, ambiguity resolution, software development and data processing and the determination of perturbed orbits.
Author: Fritz K. Brunner
Publisher: Springer Science & Business Media
ISBN: 3662037149
Category : Science
Languages : en
Pages : 407
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Book Description
IAG Scientific Assembly, Rio de Janeiro, Brazil, September, 3-9, 1997
Author: Peter J.G. Teunissen
Publisher: Springer Science & Business Media
ISBN: 3642720110
Category : Science
Languages : en
Pages : 629
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Book Description
An in-depth description of the theory and mathematical models behind the application of the global positioning system in geodesy and geodynamics. The contributions by leading experts in the field ensure a continuous flow of ideas and developments. The mathematical models for GPS measurements are developed in the first half of the book, and these are followed by GPS solutions for geodetic applications on local, regional and global scales.
