Solução rápida das ambigüidades GPS para aplicações no posicionamento relativo de linhas de base curtas
Data
2002
Autores
Machado, Wagner Carrupt [UNESP]
Título da Revista
ISSN da Revista
Título de Volume
Editor
Universidade Estadual Paulista (Unesp)
Resumo
O posicionamento com GPS no nível de precisão centimétrico é baseado na medida da fase de batimento da onda portadora. No entanto, esta observável é ambígua de um número inteiro de ciclos entre as antenas do satélite e do receptor no instante da primeira observação, denominado de ambigüidade GPS. Tais ambigüidades são introduzidas como parâmetros nas equações de observação e, devido à sua natureza inteira, não existe um método padrão para solucioná-las diretamente. Uma estratégia comumente utilizada é aplicar o método dos mínimos quadrados seqüencial condicionado juntamente com técnicas de busca. A resolução das ambigüidades pode ser dividida em duas etapas: a estimação e a validação. A estimação diz respeito ao cálculo do valor da ambigüidade. A validação é utilizada para inferir se a solução pode ser aceita ou não. Desde o final da década de 1980, até os dias de hoje, a solução da ambigüidade vem sendo um dos principais tópicos de pesquisa em posicionamento geodésico e vários métodos foram propostos. Atenção especial vem sendo dada à solução rápida das ambigüidades. Essa dissertação apresenta uma nova contribuição no desenvolvimento do software GPSeq, o qual é um software de processamento de dados GPS desenvolvido em meio acadêmico. Inicialmente, o software comportava apenas o processamento de dados coletados através de posicionamento relativo estático de linhas de base curtas. Durante o desenvolvimento de um projeto de iniciação científica (IC) financiado pela Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), o método LAMBDA...
Centimeter level GPS positioning is based on the very precise carrier beat phase measurements. However, this observable is ambiguous by a number of whole cycles between the satellite and receiver antenna at the first epoch of data collecting, which is called the ambiguity. GPS ambiguities are introduced as parameters to be estimated in the observation equations. However, since they are integer numbers there is no standard techniques for solve them. One of the ways is to apply sequential conditional least-squares estimation together with integer search techniques. The ambiguity resolution can be divided in two steps: estimation and validation. The estimation is concerned with the computation of the ambiguities values. The validation step is used to infer if the estimated value can be accepted or not. From the last decade until nowadays ambiguity resolution has been one of the most important research topic in geodetic positioning and a several methods have been proposed. Special attention has been made about the fast ambiguity resolution. This project presents a new contribution to the GPSeq software implementation, which is a GPS data processing software developed in academic environment. Initially, the software was able to process data from static relative positioning for short baselines. During the development of a Scientific Initiation project supported by FAPESP (Fundação de Amparo a Pesquisa do Estado de São Paulo), the LAMBDA method for rapid ambiguity resolution was implemented. In this contribution, local Detection Identification Adaptation (DIA) for float quality control and an algorithm for processing both, kinematic and static relative data, was implemented. An initial study about fixed ambiguity validation was also carried out. Some experiments are presented, whose results shown that the GPSeq solution is compatible on the centimeter level with commercial software... (Complete abstract click electronic address below)
Centimeter level GPS positioning is based on the very precise carrier beat phase measurements. However, this observable is ambiguous by a number of whole cycles between the satellite and receiver antenna at the first epoch of data collecting, which is called the ambiguity. GPS ambiguities are introduced as parameters to be estimated in the observation equations. However, since they are integer numbers there is no standard techniques for solve them. One of the ways is to apply sequential conditional least-squares estimation together with integer search techniques. The ambiguity resolution can be divided in two steps: estimation and validation. The estimation is concerned with the computation of the ambiguities values. The validation step is used to infer if the estimated value can be accepted or not. From the last decade until nowadays ambiguity resolution has been one of the most important research topic in geodetic positioning and a several methods have been proposed. Special attention has been made about the fast ambiguity resolution. This project presents a new contribution to the GPSeq software implementation, which is a GPS data processing software developed in academic environment. Initially, the software was able to process data from static relative positioning for short baselines. During the development of a Scientific Initiation project supported by FAPESP (Fundação de Amparo a Pesquisa do Estado de São Paulo), the LAMBDA method for rapid ambiguity resolution was implemented. In this contribution, local Detection Identification Adaptation (DIA) for float quality control and an algorithm for processing both, kinematic and static relative data, was implemented. An initial study about fixed ambiguity validation was also carried out. Some experiments are presented, whose results shown that the GPSeq solution is compatible on the centimeter level with commercial software... (Complete abstract click electronic address below)
Descrição
Palavras-chave
Sistema de Posicionamento Global, GPS (Programa de computador), Cartografia
Como citar
MACHADO, Wagner Carrupt. Solução rápida das ambigüidades GPS para aplicações no posicionamento relativo de linhas de base curtas. 2002. 128 f. Dissertação (mestrado) - Universidade Estadual Paulista, Faculdade de Ciências e Tecnologia, 2002.