No description available.

O GPS é um sistema de radio navegação baseado em satélites operando 24 horas por dia no fornecimento de sinais de rádio para determinação de coordenadas em todo o globo terrestre. Estas coordenadas apresentam uma precisão de 10 metros, que em muitas aplicações é inadequada. O DGPS ou GPS diferencial é uma técnica que permite passar a precisão para o nível do metro por meio da recepção de informações adicionais. Estas informações são recebidas pelo receptor de GPS por meio de rádio a partir de satélites geo-estacionários ou enlaces locais. Este trabalho apresenta um sistema DGPS com enlace local para aplicações urbanas com a utilização de um receptor de mensagens de texto, e de baixo custo, pager Motoro-la Creatalink operando na faixa de 931 MHz. Foi montado um projeto piloto na Escola de Engenharia de São Carlos (EESC) com a Base de Referência no Departamento de Engenharia Elétrica. Os resultados mostram que o método apresenta uma sensível melhora na qualidade das coordenadas e que apresenta um grande potencial para aplicação em cidades de médio porte. / GPS is a radio navigation system base on a satellite network providing 24 hours radio data to determine point coordinates and world wide coverage. The precision is in the decametric range which is not adequate to many applications. DGPS or Differential GPS is a technique used to improve this precision down to metric level adding informa-tion to the receiver. The GPS receiver can receive the information from geostationary satellites or radio links. This work presents a DGPS system with local radio link to support urban applications based on the low price pager Motorola Creatalink, operating in 931 MHz band. A pilot project was developed at the Engineering School of Sao Carlos (EESC) with the Refer-ence Station at the roof of Electrical Engineering Department. The results show a good improvement in the precision of the coordinates, presenting a high potential usage in medium size cities.

O GPS é um sistema de radio navegação baseado em satélites operando 24 horas por dia no fornecimento de sinais de rádio para determinação de coordenadas em todo o globo terrestre. Estas coordenadas apresentam uma precisão de 10 metros, que em muitas aplicações é inadequada. O DGPS ou GPS diferencial é uma técnica que permite passar a precisão para o nível do metro por meio da recepção de informações adicionais. Estas informações são recebidas pelo receptor de GPS por meio de rádio a partir de satélites geo-estacionários ou enlaces locais. Este trabalho apresenta um sistema DGPS com enlace local para aplicações urbanas com a utilização de um receptor de mensagens de texto, e de baixo custo, pager Motoro-la Creatalink operando na faixa de 931 MHz. Foi montado um projeto piloto na Escola de Engenharia de São Carlos (EESC) com a Base de Referência no Departamento de Engenharia Elétrica. Os resultados mostram que o método apresenta uma sensível melhora na qualidade das coordenadas e que apresenta um grande potencial para aplicação em cidades de médio porte. / GPS is a radio navigation system base on a satellite network providing 24 hours radio data to determine point coordinates and world wide coverage. The precision is in the decametric range which is not adequate to many applications. DGPS or Differential GPS is a technique used to improve this precision down to metric level adding informa-tion to the receiver. The GPS receiver can receive the information from geostationary satellites or radio links. This work presents a DGPS system with local radio link to support urban applications based on the low price pager Motorola Creatalink, operating in 931 MHz band. A pilot project was developed at the Engineering School of Sao Carlos (EESC) with the Refer-ence Station at the roof of Electrical Engineering Department. The results show a good improvement in the precision of the coordinates, presenting a high potential usage in medium size cities.

International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Low cost, commercial off-the-shelf Global Positioning System (GPS) receivers can be used to provide real-time track of ground launched subsonic, sea-skimming missile targets when integrated with existing telemetry equipment and commercial radio modems. GPS reference stations can be deployed that are capable of generating, broadcasting and monitoring Differential GPS corrections that effectively eliminate the deliberate position errors imposed by the Department of Defense. Commercial GPS receivers are effective and provide contiguous position data even during the boost phase of flight when G forces exceed the receiver manufacturer’s published specifications.

This thesis evaluates a hypothesis about how to implement a low cost Differential GPS (DGPS) solution, able to find a current location with a precision almost as good as more expensive DGPS solution.  For this purpose two Smartphone’s are used, one used as a fixed reference station and another used as a roving receiver. The reference station calculates the temporary error at its location at every second and transmits these errors to a server over the internet.  The roving receiver requests to the server to get the latest error from the reference station over the internet. By using these errors or differences, the roving receiver finds a corrected location. The results are in the same range as dedicated DGPS solutions.

The thesis deals with the possibility of fixing the position of the machine through the use of satellite systems for agriculture. It is divided into theoretical and practical part. The theoretical part includes three chapters, which are described most famous satellite navigation systems which include GPS systems GLONAS, Galileo and Beidou. Most attention is paid to the GPS system, the work is described its history, functions, each system accuracy, influences affecting the precision guidance signals and correcting their mistakes. Error correction is divided into DGPS, RTK and VRS RTK systems. This is followed by describing the indicators that affect the accuracy of broadcast signals from space satellites. The last theoretical part describes the benefits of parallel guidance of machinery in agriculture in collaboration with boundary management. The practical part is focused on field trail measure, which described the impact of working conditions stand for precision guidance for land assessment and evaluation of the measurement results.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / To make the DGPS data link can be easily modified and updated, the ‘software radio’ technology becomes a logical architecture choice applying in a DGPS transceiver. This paper will discuss the system architecture and the key technology of software DGPS transceiver, which will become a multi-band and multi-function transceiver. It will operate at the uniform hardware platform to realize two receivers’ functions ¾ both the GPS receiver and the data link receiver (or transmitter). Then, this paper will give the design and implementation of the transceiver. Finally, it will demonstrate the simulation results of the system.

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No description available.

Network-based Differential GPS (DGPS), regardless of its global, regional or local scales, is enabling technology to improve GPS positioning accuracy from tens of meters, to the levels of meters, decimetres and centimetres level in real time, depending on geographical coverage of the network and measurement types. The method is to use the data from a permanent network of reference stations to model errors due to inaccurate GPS satellite orbit ephemeris and clock data, ionospheric and tropospheric effects as well as other GPS satellite and receiver biases. Then error correction messages can be sent to users via any communication link in real time. This PhD research involves algorithm development for generating satellite orbit and tropospheric delay corrections using a regional or local reference network, especially tropospheric grid corrections, which have not been included in the existing DGPS correction vector messages, for the next generation of regional GNSS positioning services. Contributions of the research are made in the following three areas: First of all, research has been undertaken to test orbit interpolation methods, in order to represent GPS orbits and orbital corrections accurately and efficiently for (near) real-time GPS applications. For precise and predicted GPS orbits given in SP3 format and orbital corrections with respect to the broadcast ephemeris, numerical tests were conducted using different terms of Lagrange, Chebyshev and trigonometric polynomial functions. Secondly, this research has implemented a short-arc (9-hour) sliding-window orbit monitoring strategy to identify larger orbit errors in the predicted part of IGS ultra-rapid orbit solutions in near real time, using GPS tracking data from a regional network around Australia. The strategy is to predict the uncertainty estimates of each orbit over a short orbit arc in near real time, which allows users to down-weight the problematic satellites and reduces the effects of orbital errors for improved near real time ZTD estimation. Unlike long-arc orbit determination, we only estimate 6 orbital elements for each satellite. Finally, this research has proposed a new tropospheric delay correction model, which uses the Ordinary Kriging (OK) method to interpolate the residual ZTD within a regional area GPS network to improve the positioning accuracy. ZTD estimates from 129 EUREF Permanent Network (EPN) stations across Europe for over 3 months and from 17 GPSnet reference stations (Victoria, Australia) for one week were collected and processed for this study, respectively. It is concluded that interpolating residual ZTD is an efficient way to improve regional area differential GPS positioning.