Dinâmica ressonante de alguns satélites artificiais terrestres no sistema Terra-Lua-Sol

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Investigações sobre o impacto da modernização do GNSS no Posicionamento

Pós-graduação em Ciências Cartográficas - FCT

Avaliação operacional do controle mecânico de plantas aquáticas imersas no reservatório de Jupiá

O presente trabalho foi realizado com o objetivo de estudar a coleta e o descarte de plantas aquáticas em diferentes locais e infestações do sistema Tietê/Paraná, no reservatório de Jupiá. A operação foi realizada com auxílio de instrumentação instalada em uma colhedora de plantas aquáticas, com sistema de GPS dotado de sinal de correção diferencial. Os tempos gastos para carregar e descarregar a colhedora foram determinados por cronometragem, e a distância do ponto final de coleta ao ponto de descarte e o tempo de deslocamento, por cronometragem e uso de GPS convencional. em algumas coletas foram demarcados polígonos, instruindo-se o operador a trabalhar exclusivamente na área correspondente. A interpretação dos resultados permitiu determinar a participação do tempo de coleta em relação ao tempo total de operação, indicando um valor significativo do ponto de vista operacional (>70%). Considerando o descarte em áreas infestadas com taboa, o deslocamento total médio foi de apenas 383 m, com gasto médio de 200,96 s. Os valores de capacidade operacional da colhedora oscilaram entre 0,23 e 1,60 ha h-1, indicando valor médio de 4,48 ha dia-1. A maior limitação à capacidade operacional associou-se à velocidade média de deslocamento, com maior agravante em áreas com altas infestações ou profundas. Considerando-se o deslocamento da colhedora, houve grande dificuldade de orientação em condições normais de operação, inviabilizando a manutenção de espaçamentos uniformes entre as faixas de coleta e sobrepondo as passagens. Conclui-se que a avaliação operacional indicou a impossibilidade de operar a colhedora sem o auxílio de um sistema de navegação que permita orientar a sua movimentação nas áreas de controle.

Some Initial Conditions for Disposed Satellites of the Systems GPS and Galileo Constellations

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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)

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.

Sistema GPS: uma órbita em evolução - número de satélites e periodicidade

The objective of this project was to monitor the satellites of the Global Positioning System (GPS) from a fixed point on Earth and to verify the rate of recurrence respect to their rotation and displacement. A topographic GPS signal receiver connected to a personal computer was used to recorded, for five days, the displacement of the satellites. This work was based on the fact that many literature references state that satellites complete one orbit around the Earth every 12 hours, then, it is assumed that the satellite would be seen twice in a day from the same fixed point on Earth.Although, this does not occur, as thise time interval correspond to 12 hours sidereal time and not solar time. In addition, this study was carried out in order toconfirm and update the information related to the number of satellites in operation today, found to be 31. In that sense, some references concerning the space segment of this system were defined in details.

Carga de trabalho de equinos da raça Quarto de Milha monitorados com Sistema de Posicionamento Global (GPS) e monitor cardíaco durante exercício de Três Tambores

Pós-graduação em Biotecnologia Animal - FMVZ

Levantamento planimétrico de pequenas propriedades rurais pelo sistema convencional e pelo receptor (gps) de navegação

The present study aimed to compare the planimetric survey data of an area equivalent to a small rural property, through values of longitudes e latitudes obtained by a GPS navigation with a conventional survey data. The value of the area obtained with the navigation receiver showed a small difference when compared with the conventional system. Points located under large vegetal cover had impaired reading of coordinates. The navigation receiver can be used to get measurements inside the property for planning purposes and also for measuring he land perimeter, but not for legal purposes. The Google planimeter result in the same area as the one from the conventional survey data.

Metodologia para avaliação do desempenho de receptor de GPS de uso agrícola em condição cinemática

Activities that use Global Navigation Satellite System (GNSS) are countless and the most used one is the Global Positioning System (GPS) developed by the United States. In precision agriculture there are demands for static and cinematic positioning with distinct levels of accuracy for different applications; nevertheless cinematic performance data are not available as manufacturers of GPS receivers present only static performance information. For this reason it was developed an instrumented vehicle to test a methodology of performance evaluation of GPS receivers in kinematic conditions, which is representative to agricultural operations. A set of instrumentation was composed and used for collecting data under variable speed and rotation direction. Tests were conducted showing that the methodology allows to measure accuracy and precision, but improvements have to be implemented on the instrumentation equipment for long term tests.

Assimilação do IWV-GPS no Brasil: otimização das estimativas do atraso zenital troposférico em tempo real

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

Determinação altimétrica através do sistema de posicionamento global

Este estudo tem por objetivo verificar a influência do tempo de coleta de dados com receptores GPS nas determinações altimétricas. O levantamento altimétrico é realizado através do método de posicionamento relativo estático, utilizando dois receptores GPS de uma freqüência, em diferentes tempos de ocupação (30, 15, 10 e 5 minutos) com uma taxa de gravação de dois segundos. As altitudes obtidas com receptores GPS são comparadas com as altitudes determinadas por nivelamento trigonométrico com Estação Total. Os resultados mostraram que os tempos de ocupação menores que 30 minutos (15, 10 e 5 minutos) também são adequados para a obtenção de diferenças centimétricas nas altitudes analisadas. Mesmo considerando a precisão dos métodos topográficos convencionais, este estudo demonstra a possibilidade da utilização do Sistema de Posicionamento Global (GPS) de forma precisa nos levantamentos altimétricos, desde que se efetue a modelagem da ondulação geoidal.

Implantação do pilar ruju Botucatu na UNESP para integração ao Sistema Geodésico Brasileiro

The objective of this work was to implant a geodesic pillar in the campus of Botucatu (Rubião Júnior) of the São Paulo State University (UNESP), using active stations of the Brazilian Net of Continuous Monitoring (RBMC) as reference, aiming at inclusion in the Brazilian Geodesic System (BGS). In the planning of the trace, some aspects of the pillar optimization were considered: the field evaluation, the equipment Receiver GPS Topcon Hiper GGD and the net RBMC were used to trace the height, and the Topcon Tools 6.04 version software was use for the data processing, the ambiguity solution, as well as the treatment of injunctions during the column adjustment. The obtained results allowed the implantation of a more accurate pillar then 1ppm compatible to the RBMC net, meeting the specification of IBGE.

Planejamento agrícola e implantação de sistema de cultivo de cana-de-açúcar com auxílio de técnicas geoestatísticas

Sugarcane is one of the most important crops of the Brazilian agribusiness and this importance justifies the use of techniques that allow the implementation of cultivation systems capable of reducing the variability of soil characteristics and the establishment of efficient agricultural planning. The aim of the present work was the planning and implementation of cultivation systems for sugarcane using geostatistical techniques, in the Pereira Barreto region, SP. An area of 505 ha was mapped using the global positioning system (GPS) and a Digital Elevation Model was elaborated (MDE). Soil samples were collected for 0-0.25 m depth, in each 7 ha, for their chemical attributes and texture characterization. Data were analyzed by descriptive statistics and geostatistics. The determination of the spatial distribution of soil granulometric and chemical attributes allowed the allocation of the studied sugarcane varieties according to soil fertility and clay content. The kriging maps of soil granulometric and chemical attributes brought useful information to the establishment of production environments with different soil and crop managements. The identification of different environments by means of geostatistical techniques allowed the precise planning of the sugarcane cultivation, as well as the adequacy of fertilization practices and the allocation of suitable sugarcane varieties adapted to the conditions imposed by differences in the soil attributes.

Galileo's surveying potential E5 pseudorange precision

New Galileo signals have great potential for pseudorange-based surveying and mapping in both optimal open-sky conditions and suboptimal under-canopy environments. This article reviews the main features of Galileo's E5 AItBO( and El (BOC signals, describes generation of realistic E5 and El pseudoranges with and without multipath sources, and presents anticipated horizontal positioning accuracy results, ranging from 4 centimeters (open-sky) to 14 centimeters (under-canopy) for E5/El.