No description available.

No description available.

International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The accurate determination of test aircraft position and velocity is a very strong requirement in several certification and development flight test applications. This requirement often requires availability of test ranges properly instrumented with optical or radar tracking systems, precision time for data reduction and dependency on environmental and meteorological conditions. The capabilities of GPS (Global Positioning System) technology, in terms of data accuracy, speed of data availability and reduction of test operating cost, moved Bombardier Flight Test Center to make an investment and integrate a system utilizing GPS for extensive use in flight and ground test activity. Through the use of differential GPS (DGPS) procedures, Bombardier Flight Test Center was able to implement a complete system which could provide real-time data results to a very acceptable output rate and accuracy. Furthermore, the system was capable of providing post-processed data results which greatly exceeded required output rate and accuracy. Regardless of the type of aircraft testing conducted, the real-time or post-processed data could be generated for the same test. After conducting various types of testing, Bombardier Flight Test Center has accepted the DGPS as an acceptable and proper flight and ground test measurement tool for its various aircraft test platforms.

Resumo: Atualmente é cada vez mais presente na comunidade civil a utilização do Global Positioning System (GPS). Um dos métodos de posicionamento GPS de grande destaque é o Differential GPS (DGPS). Esse método utiliza dois receptores, um como base e outro como móvel. O DGPS tem como princípio básico considerar a alta correlação dos erros provocados pela ionosfera, troposfera e órbita dos satélites. No entanto, com o afastamento entre o usuário e a estação base, a eficiência do método diminui, pois a correlação dos erros é reduzida. Mas, quando se utiliza uma rede de estações de referência, pode-se ter uma melhor modelagem dos erros na área de abrangência da rede. Surge então o conceito de DGPS em Rede (DGPSR). Alguns experimentos realizados com o DGPSR em modo pós-processados apontaram acurácia da ordem de 50 cm. Portanto, nesta pesquisa foi proposta a implementação do DGPSR em tempo real. As correções DGPSR são calculadas em tempo real por meio dos dados obtidos via Internet utilizando o protocolo Ntrip (Networked Transport of RTCM via Internet Protocol). Para isso, foram introduzidas várias alterações no software BNC, software este que foi desenvolvido pelo BKG e realiza a função do NtripClient. No que concerne às estações de referência GPS, foram utilizados dados da rede GNSS do oeste do estado de São Paulo (Rede GNSS/SP). A rede está composta, até o momento, por 10 receptores de alta tecnologia que podem ser conectados diretamente a Internet. Com relação aos resultados pode-se observar que o DGPSR utilizando 4 estações de referência apresentou melhorias de até 32% em planimetria e de 28% em altimetria, quando comparados ao DGPS utilizando somente uma estação de referência. Com relação a avaliação da latência pode-se verifica que latências de até 12 segundos parecem não causar influência nos resultados. / Abstract: Nowadays, the Global Positioning System (GPS) has been very used by the civil community. One of the GPS positioning methods that have been emphasized is the Differential GPS (DGPS). In this method, two receivers are used. One of them as base and the other as rover station. The DGPS has the basic concept of considering high correlation of the errors caused by ionosphere, troposphere and satellite orbits. However, with the baseline growth the method efficiency decreases, because the errors correlation is reduced. But, using a reference station network it is possible to obtain an error modeling in the area of the network, using the network DGPS concept. Some experiments accomplished with DGPSR post processed mode presented promising results. Accuracy better than 50 cm was obtained. Therefore, in this research the goal is to implement the DGPS in real time. The corrections will be computed through data received by Internet using the Ntrip (Networked Transport of RTCM via Internet Protocol). In order to accomplish that, it was implemented several modifications in the BNC software. This software was developed by BKG and make the function of a NtripClient. It will be used a GPS network that is set up in the west of São Paulo State. This network is composed by 10 receivers of high technology that can be directly connected by Internet. Regarding the results, the DGPSR using 4 reference stations showed improvements of up to 32% in planimetry and 28% in altimetry when compared to pure DGPS. Regarding the assessment of latency it was noted that latencies of up to 12 seconds seems not to cause influence the results. / Orientador: João Francisco Galera Monico / Coorientador: Milton Hirokazu Shimabukuro / Coorientador: Daniele Barroca Marra Alves / Banca: Eniuce Menezes de Souza / Banca: Eno Darci Saatkamp / Mestre

<p>This Master’s thesis is a pilot study that investigates different systems to drive autonomous and non-autonomous vehicles simultaneously on test tracks. The thesis includes studies of communication, positioning, collision avoidance, and techniques for surveillance of vehicles which are suitable for implementation. The investigation results in a suggested system outline.</p><p>Differential GPS combined with laser scanner vision is used for vehicle state estimation (position, heading, velocity, etc.). The state information is transmitted with IEEE 802.11 to all surrounding vehicles and surveillance center. With this information a Kalman prediction of the future position for all vehicles can be estimated and used for collision avoidance.</p>

This Master’s thesis is a pilot study that investigates different systems to drive autonomous and non-autonomous vehicles simultaneously on test tracks. The thesis includes studies of communication, positioning, collision avoidance, and techniques for surveillance of vehicles which are suitable for implementation. The investigation results in a suggested system outline. Differential GPS combined with laser scanner vision is used for vehicle state estimation (position, heading, velocity, etc.). The state information is transmitted with IEEE 802.11 to all surrounding vehicles and surveillance center. With this information a Kalman prediction of the future position for all vehicles can be estimated and used for collision avoidance.

Orientador: Nelson Luis Cappelli / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agricola / Made available in DSpace on 2018-08-06T21:31:33Z (GMT). No. of bitstreams: 1 Lima_ThalesCoelhoBorges_D.pdf: 3224309 bytes, checksum: 0b88922a88b1f511034fc43574f8d0e3 (MD5) Previous issue date: 2006 / Resumo: Este trabalho apresenta o desenvolvimento de um equipamento microprocessado, de custo reduzido, para geração de sinal de correção diferencial para GPS, em tempo real e configuração e supervisão do receptor GPS base. Foi estruturado em duas etapas. Na primeira, desenvolveu-se um protótipo com o intuito de comprovar a viabilidade técnica e econômica e na segunda, o desenvolvimento do equipamento de correção diferencial capaz de atuar de forma autônoma. O aplicativo computacional desenvolvido é responsável pela geração do sinal de correção diferencial no formato do protocolo RTCM SC-104, configuração e inicialização do receptor GPS e operações de geo-referenciamento. O equipamento de correção diferencial possui um microcontrolador dedicado, display alfanumérico, teclado multifunção para configuração e operação do sistema e interfaces de comunicação. A placa processadora possui duas interfaces seriais padrão RS-232C. Uma delas tem a função de configuração e leitura das informações geradas pelo receptor GPS base. A outra atua somente como saída, enviando o sinal de correção diferencial. Desenvolveu-se um sistema de modulação/demodulação e conversão de taxa, de custo reduzido, para ajustar o sinal ao meio de comunicação. Este sistema é constituído por dois módulos independentes, onde um deles está conectado ao equipamento de correção diferencial na transmissão e o outro no módulo receptor para o envio ao receptor GPS móvel. Fez-se uso de rádios de comunicação VHF/UHF para o envio do sinal de correção. Foram realizados diversos testes ao longo do desenvolvimento de todas as etapas deste trabalho. Inicialmente, avaliou-se o aplicativo computacional responsável pela geração do sinal de correção diferencial no formato RTCM-SC 104. Nos testes subseqüentes avaliaram-se o sistema de comunicação proposto, as rotinas desenvolvidas para a configuração do receptor GPS e o equipamento de correção diferencial final. O projeto do equipamento microprocessado mostrou que é possível a construção de uma estação privada para a geração do sinal de correção diferencial, de custo reduzido, possibilitando o aumento do número de usuários no segmento agrícola, por meio da redução do custo dos sistemas de posicionamento / Abstract: This work presents the development of low cost microprocessor-based equipment that generates differential correction signal to GPS, in real time, and the configuration and supervision of GPS base receptor. It was structured in two phases. In the first one, a prototype was developed aiming to prove its economical and technical viability and in the second one, the development of the equipment of differential correction able to act in an autonomous way. The computer application developed is responsible to generate the differential correction signal in the RTCM SC-104 protocol format, the configuration and initialization of the GPS receptor and the geo-reference operations. The equipment developed has a dedicated microcontroller, alphanumeric display, multifunctional keyboard for the configuration and operation of the system and the communication interfaces. The motherboard has two serial interfaces RS-232C standard. The first interface function is to configure and to read the information generated by the GPS base receptor. The second performs only as ¿gate¿, to send the differential correction signal. A low cost system of modulation/demodulation and ¿tax¿ conversion was developed, to adjust the signal and communication channel. This system has two independent modules, one module is connected to the differential correction equipment in the transmission and the second is connected to the receptor to send the signal to the mobile GPS. Radio communication UHF/VHF was used to send the correction signal. Several tests were performed during the all the phases of the development. First, the computer application responsible to generate the differential correction signal RTCM-SC 104 standard was evaluated. Second, the proposed communication system and the configuration routines for the GPS receptor and the final differential correction equipment were tested. The micro processed equipment project proved that is possible to build a private low cost station to generate the differential correction signal, allowing the increase the number of agriculturist business users, by reducing the cost of the positioning systems / Doutorado / Maquinas Agricolas / Doutor em Engenharia Agrícola

>Magister Scientiae - MSc / Globally climate variability and anthropogenic effects are causing more perennial rivers to become non-perennial rivers. Non-perennial rivers are distinguished by their isolated pools which serve as refugia for aquatic organisms, water birds, and riparian vegetation. The literature on non-perennial rivers demonstrates that pools are poorly understood in terms of their location, nature, and geomorphic persistence. Therefore, this study examines the relationships between the spatial distribution, morphology, and substrate characteristics of pools in reaches of the Prins and Touws rivers in the Klein Karoo. A greater understanding of pools will facilitate better management, monitoring, and restoration strategies for pool ecology since the geomorphology of pools provides a key part of the ecological template. Worldview-2 satellite imagery (2017) and orthorectified aerial photography (2014, 2013, and 1944) were used to assess the effects of major flooding events on pools over time. A DGPS (Differential Global Positioning System) was used to survey the pool widths, lengths, depths, and valley widths, cross-sections, and longitudinal profiles of the river. Sediment samples and Wolman pebble counts were used to assess the grain size and organic matter content of each pool in the study area. Detailed descriptions of the characteristics of each pool in terms of position in the channel, valley form, and obstruction presence and type were also assessed. Results indicate that most of the large pools occur at bedrock outcrops of the valley margins, and smaller pools are associated with Vachellia karroo debris bar features. Larger and highly persistent pools are associated with valley confinement and smaller less persistent, scour pools occur mid-channel where the valley expands. Analysis of the results shows that the valley width is the dominant control on these forced pools. The type of obstruction also plays a role in the formation of the pool as large woody debris results in smaller pools whereas, bedrock outcrops result in larger sized pools. A significant relationship was found between the grain size and organic matter content of pools. Aerial photography of the spatial distribution of the pools revealed that before a major flood, the pools were small and patchy, whereas afterward, they were larger and more elongated. It is suggested that at the bedrock outcrops, major scouring and eddy processes drive the formation of larger pools during large flood events, whereas pool dissection by sediment deposits prevails during intervening intermediate to low flow periods. The results are discussed in terms of the geomorphic controls (valley width, pool dimensions, morphology, substrate, and obstruction characteristics) on the formation and maintenance of pools in dryland settings. A conceptual model is proposed to explain the geomorphic changes of the pools in the four geomorphological zones of non-perennial rivers.

This master’s thesis is the design of the system of the differential GPS, creation of the software for basic wireless communication between 2 GPS receivers, and practical tests of the designed system. Parameters and characteristics of system were determined and they should inform us better about the appropriateness of the designed system for navigation of a mobile robot in outside conditions.

O desenvolvimento técnico da eletrônica, a contínua redução do tamanho dos receptores GNSS, associada à diminuição do consumo de energia, transformaram estes produtos em alguns circuitos integrados ou apenas pequenos chips do tamanho de um botão de uma camisa. Desta forma pode-se promover a sua integração com inúmeros dispositivos eletrônicos. A associação com os telefones celulares foi principalmente impulsionada pelo mandato de aprimoramento dos serviços 911 (E911) da Federal Communications Commission (FCC) nos Estados Unidos, exigindo que todas as operadoras de telefonia móvel daquele país fornecessem a localização com boa precisão das chamadas de emergência. Esta necessidade estimulou a produção dos chips em larga escala e, portanto, a diminuição do custo e a sua popularização. Desta maneira quase que em sua totalidade, os telefones celulares são hoje fabricados com receptores GPS, o que torna estes dispositivos uma das fontes mais baratas de se obter o Geoposicionamento. Acontece que existe uma lacuna na literatura quanto à precisão e a exatidão das coordenadas fornecidas por estes equipamentos. O presente trabalho visa, através de testes estatísticos e da comparação com outros receptores GPS e métodos, quantificar estes valores e propor uma metodologia para melhorar tal posicionamento. Para conseguir o objetivo, a estrutura do Sistema Operacional do telefone foi modificada de tal modo que fosse possível o acesso às observáveis do chipset do GPS embarcado e convertidos para o padrão RINEX de arquivamento de dados brutos. Os testes foram executados com o equipamento original e com o equipamento modificado com a instalação de uma antena externa e mostraram que com a utilização da medida de fase da portadora o equipamento pode fornecer o posicionamento com uma precisão média de 0,069m, com o desvio padrão de 0,047m e erro planimétrico de posicionamento máximo de 0,218m e mínimo de 0,004m. / The technical development of electronics, the continuous reduction in the size of GNSS receptors, allied with the energy consumption decrease, transformed these products into some integrated circuits or in small Chips as small as size of a button of a shirt. In this way one can promote its integration with countless electronic devices. The association with cell phones was mainly driven by the mandate to enhance services 911 (E911) of the Federal Communications Commission (FCC) in the United States, requiring that all mobile carriers of that country provide all the emergency calls location with good accuracy. So as to fulfill this necessity, the production of Chips in a large scale has been stimulated and therefore the decrease in cost and its popularity. In this way almost in its entirety, cell phones are now manufactured with GPS receivers, which makes these devices one of the cheapest sources to obtain the geopositioning. It turns out that there is a gap in the literature about how precise and accurate the coordinates provided by these equipments can be. This thesis aims through statistical tests and comparison with other GPS receivers and methods, quantify these values and propose a methodology to improve such positioning. To achieve the objective, the structure of the phone\'s operating system was modified in such a way that it was possible to access the embedded GPS Chipset observables and then converted into the RINEX standard raw data file. The tests were carried out with the original equipment and with the modified ones, with an external antenna installation which showed that using the phase measure of the carrier, the equipment can provide a positioning with an average accuracy of 0, 069m, with a default deviation of 0, 047m and a maximum planimetric positioning error of 0, 218m and a minimum of 0, 004m.