Modeling and Modification of Global Positioning System Tropospheric Delay Mapping Function

The accuracy of Global Positioning System (GPS) measurement is determined by the sum of several sources of error, such as orbit error, satellite clock error, multipath error, receiver noise error, selective availability, ephemeris error and also atmospheric error. The principal error source in the G...

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Main Author:	Sakidin, Hamzah
Format:	Thesis
Language:	English English
Published:	2008
Subjects:	Global Positioning System.
Online Access:	http://psasir.upm.edu.my/id/eprint/5145/1/FS_2008_32.pdf
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spelling	my-upm-ir.51452013-05-27T07:20:42Z Modeling and Modification of Global Positioning System Tropospheric Delay Mapping Function 2008 Sakidin, Hamzah The accuracy of Global Positioning System (GPS) measurement is determined by the sum of several sources of error, such as orbit error, satellite clock error, multipath error, receiver noise error, selective availability, ephemeris error and also atmospheric error. The principal error source in the GPS technology is a delay experienced by the GPS signal in propagating through the electrically neutral atmosphere, usually referred to as a tropospheric delay. This delay is normally calculated in the zenith direction, and is referred to as a zenith tropospheric delay. The delay consists of a zenith hydrostatic delay, which can be modeled accurately using surface barometric measurements, and a zenith wet delay, which cannot be modeled from surface barometric measurements and depends on atmospheric water vapor. The mapping function is the coefficient for the zenith delay, either hydrostatic (dry) or non-hydrostatic (wet) delay that can be used to increase or reduce the tropospheric delay. In this research, 3 mapping function models which are known as, and Neill () are selected to be simplified, where as 2 mapping function models which are known as and Neill () are selected to be modified. For the simplification of the mapping function models, regression method has been used to find the suitable equation. The simplified mapping function models for, and Neill (), can reduce the computing time by reducing the percentage of number of operations between 71.4% to 92.3% for linear equations and 28.6% to 80.8% for quadratic equations. The calculations of the sum of errors show that the deviation of the simplified model from the original model is not significant. The simplification of the mapping function models can also create better understanding of the models by using hyperbolic, linear and also quadratic equations rather than continued fractions. Results indicate that the modification of the mapping function models can give smaller value especially for less than 5 degree elevation angles. As the coefficient of the zenith delay, it can improve the tropospheric delay directly. The improvement of the tropospheric delay for UNBabcand Neill mapping functions,can be obtained up to 19.1% and 17.8% respectively at 2 degree elevation angle. Global Positioning System. 2008 Thesis http://psasir.upm.edu.my/id/eprint/5145/ http://psasir.upm.edu.my/id/eprint/5145/1/FS_2008_32.pdf application/pdf en public phd doctoral Universiti Putra Malaysia Global Positioning System. Science English
institution	Universiti Putra Malaysia
collection	PSAS Institutional Repository
language	English English
topic	Global Positioning System.
spellingShingle	Global Positioning System. Sakidin, Hamzah Modeling and Modification of Global Positioning System Tropospheric Delay Mapping Function
description	The accuracy of Global Positioning System (GPS) measurement is determined by the sum of several sources of error, such as orbit error, satellite clock error, multipath error, receiver noise error, selective availability, ephemeris error and also atmospheric error. The principal error source in the GPS technology is a delay experienced by the GPS signal in propagating through the electrically neutral atmosphere, usually referred to as a tropospheric delay. This delay is normally calculated in the zenith direction, and is referred to as a zenith tropospheric delay. The delay consists of a zenith hydrostatic delay, which can be modeled accurately using surface barometric measurements, and a zenith wet delay, which cannot be modeled from surface barometric measurements and depends on atmospheric water vapor. The mapping function is the coefficient for the zenith delay, either hydrostatic (dry) or non-hydrostatic (wet) delay that can be used to increase or reduce the tropospheric delay. In this research, 3 mapping function models which are known as, and Neill () are selected to be simplified, where as 2 mapping function models which are known as and Neill () are selected to be modified. For the simplification of the mapping function models, regression method has been used to find the suitable equation. The simplified mapping function models for, and Neill (), can reduce the computing time by reducing the percentage of number of operations between 71.4% to 92.3% for linear equations and 28.6% to 80.8% for quadratic equations. The calculations of the sum of errors show that the deviation of the simplified model from the original model is not significant. The simplification of the mapping function models can also create better understanding of the models by using hyperbolic, linear and also quadratic equations rather than continued fractions. Results indicate that the modification of the mapping function models can give smaller value especially for less than 5 degree elevation angles. As the coefficient of the zenith delay, it can improve the tropospheric delay directly. The improvement of the tropospheric delay for UNBabcand Neill mapping functions,can be obtained up to 19.1% and 17.8% respectively at 2 degree elevation angle.
format	Thesis
qualification_name	Doctor of Philosophy (PhD.)
qualification_level	Doctorate
author	Sakidin, Hamzah
author_facet	Sakidin, Hamzah
author_sort	Sakidin, Hamzah
title	Modeling and Modification of Global Positioning System Tropospheric Delay Mapping Function
title_short	Modeling and Modification of Global Positioning System Tropospheric Delay Mapping Function
title_full	Modeling and Modification of Global Positioning System Tropospheric Delay Mapping Function
title_fullStr	Modeling and Modification of Global Positioning System Tropospheric Delay Mapping Function
title_full_unstemmed	Modeling and Modification of Global Positioning System Tropospheric Delay Mapping Function
title_sort	modeling and modification of global positioning system tropospheric delay mapping function
granting_institution	Universiti Putra Malaysia
granting_department	Science
publishDate	2008
url	http://psasir.upm.edu.my/id/eprint/5145/1/FS_2008_32.pdf
_version_	1747810360867422208

Modeling and Modification of Global Positioning System Tropospheric Delay Mapping Function

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