Posicionamento GPS utilizando o conceito de estação virtual

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estimativas do IWV utilizando receptores GPS em bases terrestres no Brasil: sinergia entre a geodésia e a meteorologia

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Desenvolvimento de um sistema informatizado de menor custo para aquisição e armazenamento de dados de sensores analógicos e receptor GPS

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Uso do receptor GPS topográfico na obtenção de cartas e modelo digital do terreno

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Avaliação do posicionamento plano-altimétrico com receptor gps em diferentes tipos de uso do solo

Pós-graduação em Agronomia (Energia na Agricultura) - FCA

Modelo estocástico para dados GNSS e séries temporais de coordenadas GNSS

Pós-graduação em Ciências Cartográficas - FCT

Investigação da cintilação ionosférica no Brasil e seus efeitos no posicionamento por GNSS

Pós-graduação em Ciências Cartográficas - FCT

Análise de deformação da rede GNSS/SP com base na teoria da elasticidade

Pós-graduação em Ciências Cartográficas - FCT

Influence of distance, geometry and number of control stations on quality of local geodetic networks for the purpose of georeferencing of rural properties

The implementation of local geodetic networks for georeferencing of rural properties has become a requirement after publication of the Georeferencing Technical Standard by INCRA. According to this standard, the maximum distance of baselines to GNSS L1 receivers is of 20 km. Besides the length of the baseline, the geometry and the number of geodetic control stations are other factors to be considered in the implementation of geodetic networks. Thus, this research aimed to examine the influence of baseline lengths higher than the regulated limit of 20 km, the geometry and the number of control stations on quality of local geodetic networks for georeferencing, and also to demonstrate the importance of using specific tests to evaluate the solution of ambiguities and on the quality of the adjustment. The results indicated that the increasing number of control stations has improved the quality of the network, the geometry has not influenced on the quality and the baseline length has influenced on the quality; however, lengths higher than 20 km has not interrupted the implementation, with GPS L1 receiver, of the local geodetic network for the purpose of georeferencing. Also, the use of different statistical tests, both for the evaluation of the resolution of ambiguities and for the adjustment, have enabled greater clearness in analyzing the results, which allow that unsuitable observations may be eliminated.

Potencialidade do gps de navegação garmin 12 xl utilizando um sistema de baixo custo

Since 2000 the use of the GPS navigation increases considerably. The reason for that was the deactivation of the selective availability in May 2000. However, these receivers do not register the observables, they just estimate and store them and that prevents the post-processing data. Based in this aspect some softwares were developed and are available for free. They allow recording the GPS observables, pseudorange and carrier phase. These programs are able to read in binary files and record information concerning the GPS observables and to convert binary format to a RINEX format. This study presents the GPS Garmin 12 XL evaluation using free programs. Two experiments were carried out in Presidente Prudente-SP region using the relative static survey. The processing was carried out with intervals of 30, 15, 10 and 5 minutes. The results were compared with the coordinates from a geodetic receiver and show that 98.9 % of the points, the values in relation to the planimetric accuracy were better than 0.50 m. The only baseline which the value was larger or equal to 0.50 m is the point M0001 (baseline lesser than 2 km) referred to the first experiment. In terms of precision the values did not exceeded 0.30 m.

Introdução e aplicação da diluição da precisão das ambiguidades GNSS - ADOP

The main topic of this paper is the Ambiguity Dilution of Precision known as ADOP. Basically, ADOP is defined as a diagnostic measure for assessing the precision of the float scalar ambiguities. Among the several possibilities, the ADOP can provide help in predicting the behavior of a baseline or a network of GNSS receivers, concerning the problem of ambiguity resolution, either in real-time (instantaneous) or in the post-processing mode. The main advantage of using ADOP is possibility of the extraction of a closed analytical expression, considering various factors that affect the ambiguity resolution. Furthermore, the ADOP is related to the success rate of ambiguity resolution. The expressions here used, takes into account several factors, for example, a priori information of the measurement precision of GNSS carrier phase and pseudorange, the number of stations and satellites, the number of available frequencies and the behavior of the atmosphere (ionosphere and troposphere). Several scenarios were established so as to analyze the impact of each factor in ambiguities resolution, within the context of some stations of the São Paulo GNSS network (GNSS-SP).

Análise de robustez de estações da rede GNSS-SP

Currently, the need of reliable coordinates has been one of the main objectives of the scientific and practice community. Thus, the robustness analysis of a geodetic network, aims, at analyzing if the network is robust or not, based on the maximum undetectable errors. The network will be robust if the influence of these errors is small, otherwise it is weak, or not robust. This analysis is performed with the merger of two techniques, one which deals with the statistical analysis of reliability and the other one with the geometric strength analysis. The reliability analysis will provide the maximum error that cannot be detected by tests, after the adjustment. After finding these errors, the geometric strength analysis will determine the potential strain that the network will have, based on these errors. It is emphasized that the robustness analysis doesn't depend of the datum, reflecting only the geometry of the network and the accuracy of the observations (VANÌCEK et al., 2001). Therefore, this work aims at contributing to the scientific research on geodetic networks, checking the same, based on their geometry and observations.

First results from an airborne GPS radio occultation system for atmospheric profiling

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

ZTD em tempo quase real via Estações GNSS Terrestres: estratégia de processamento para o GIPSY-OASIS II e combinação das séries temporais

Pós-graduação em Ciências Cartográficas - FCT

AVALIAÇÃO ROBUSTA DA MODELAGEM NEUTROSFÉRICA SOBRE O TERRITÓRIO BRASILEIRO BASEADA EM MODELOS DE PREVISÃO NUMÉRICA DE TEMPO DA AMÉRICA DO SUL

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)