Partial Carrier-Phase Integer Ambiguity Resolution for High Accuracy GNSS Positioning PDF Download
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Author: Andreas Brack
Publisher: Verlag Dr. Hut
ISBN: 3843942293
Category : Technology & Engineering
Languages : en
Pages : 159
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Book Description
Global navigation satellite systems provide ranging based positioning and timing services. The use of the periodic carrier-phase signals is the key to fast and accurate solutions, given that the inherent ambiguities of the carrier-phase measurements are correctly resolved. The idea of partial ambiguity resolution is to resolve a subset of all ambiguities, which enables faster solutions but does not fully exploit the high precision of the carrier-phase measurements. Theory, methods, and algorithms for partial ambiguity resolution are discussed and analyzed with simulated and real data.
Author: Andreas Brack
Publisher: Verlag Dr. Hut
ISBN: 3843942293
Category : Technology & Engineering
Languages : en
Pages : 159
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Book Description
Global navigation satellite systems provide ranging based positioning and timing services. The use of the periodic carrier-phase signals is the key to fast and accurate solutions, given that the inherent ambiguities of the carrier-phase measurements are correctly resolved. The idea of partial ambiguity resolution is to resolve a subset of all ambiguities, which enables faster solutions but does not fully exploit the high precision of the carrier-phase measurements. Theory, methods, and algorithms for partial ambiguity resolution are discussed and analyzed with simulated and real data.
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:
Publisher:
ISBN:
Category :
Languages : en
Pages : 12
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Book Description
The U.S. Army Corps of Engineers has been developing a GPS carrier phase based positioning system for hydrographic surveying and dredging since 1988. This system provides real-time three dimensional positions with horizontal and vertical accuracies better the one decimeter over ranges up to 20 kilometers from a single reference station without static initialization. The project has passed from concept development through feasibility studies, system analysis, resolution of carrier ambiguities on-the-fly (OTF), to final system integration which is nearing completion. The real-time testing of the system began in March of 1993. This testing was performed under varying operating conditions to evaluate the limits of OTF ambiguity resolution for precisely positioning moving platforms. This paper will summarize the results of those tests. Early realtime tests performed have shown 1-3 centimeters in all three dimensions. The final design of the realtime system and its integration to hydrographic. survey platforms will also be discussed.
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: Sandra Verhagen
Publisher:
ISBN:
Category : Geodesy
Languages : en
Pages : 204
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Book Description
Fast and high precision relative positioning with a Global Navigations Satellite System (GNSS) is only possible by using the very precise carrier phase measurements. However, these carrier phases are ambiguous by an unknown number of cycles. The knowledge that the ambiguities are integer-valued has been exploited in the past 15 years for the development of integer ambiguity resolution algorithms.
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: Michael Joseph Gabor
Publisher:
ISBN:
Category : Global Positioning System
Languages : en
Pages : 396
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Author: John Foster Raquet
Publisher:
ISBN:
Category : Global Positioning System
Languages : en
Pages : 259
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Author: Garrett Goberdhan Seepersad
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Conventional Precise Point Positioning (PPP) has always required a relatively long initialization period (few tens of minutes at least) for the carrier-phase ambiguities to converge to constant values and for the solution to reach its optimal precision. The classical PPP convergence period is primarily caused by the estimation of the carrier-phase ambiguity from the relatively noisy pseudoranges and the estimation of atmospheric delay. If the underlying integer nature of the ambiguity is known, it can be resolved, thereby reducing the convergence time of conventional PPP. To recover the underlying integer nature of the carrier-phase ambiguities, different strategies for mitigating the satellite and receiver dependent equipment delays have been developed, and products made publicly available to enable ambiguity resolution without any baseline restrictions. There has been limited research within the scope of interoperability of the products, combining the products to improve reliability and assessment of ambiguity resolution within the scope of being an integrity indicator. This study seeks to develop strategies to enable each of these and examine their feasibility. The advantage of interoperability of the different PPP ambiguity resolution (PPP-AR) products would be to permit the PPP user to transform independently generated PPP-AR products to obtain multiple fixed solutions of comparable precision and accuracy. The ability to provide multiple solutions would increase the reliability of the solution for, e.g., real-time processing: if there were an outage in the generation of the PPP-AR products, the user could instantly switch streams to a different provider. The satellite clock combinations routinely produced within the International GNSS Service (IGS) currently disregard that analysis centers (ACs) provide products which enable ambiguity resolution. Users have been expected to choose either an IGS product which is a combined product from multiple ACs or select an individual AC solution which provides products that enable PPP-AR. The goal of the novel research presented was to develop and test a robust satellite clock combination preserving the integer nature of the carrier-phase ambiguities at the user end. mm-level differences were noted, which was expected as the strength lies mainly in its reliability and stable median performance and the combined product is better than or equivalent to any single ACs product in the combination process. As have been shown in relative positioning and PPP-AR, ambiguity resolution is critical for enabling cm-level positioning. However, what if specifications where at the few dm-level, such as 10 cm and 20 cm horizontal what role does ambiguity resolution play? The role of ambiguity resolution relies primarily on what are the user specifications. If the user specifications are at the few cm-level, ambiguity resolution is an asset as it improves convergence and solution stability. Whereas, if the users specification is at the few dm-level, ambiguity resolution offers limited improvement over the float solution. If the user has the resources to perform ambiguity resolution, even when the specifications are at the few dm-level, it should be utilized.
Author:
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ISBN:
Category :
Languages : en
Pages :
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