The integrity of positioning systems has become an increasingly important requirement for location-based Intelligent Transports Systems (ITS). The navigation systems, such as Global Positioning System (GPS), used in ITS cannot provide the high quality positioning information required by most services, due to the various type of errors from GPS sensor, such as signal outage, and atmospheric effects, all of which are difficult to measure, or from the map matching process. Consequently, an error in the positioning information or map matching process may lead to inaccurate determination of a vehicle’s location. Thus, the integrity is require when measuring both vehicle’s positioning and other related information such as speed, to locate the vehicle in the correct road segment, and avoid errors. The integrity algorithm for the navigation system should include a guarantee that the systems do not produce misleading or faulty information; as this may lead to a significant error arising in the ITS services. Hence, to achieve the integrity requirement a navigation system should have a robust mechanism, to notify the user of any potential errors in the navigation information. The main aim of this research is to develop a robust and reliable mechanism to support the positioning requirement of ITS services. This can be achieved by developing a high integrity GPS monitoring algorithm with the consideration of speed, based on the concept of context-awareness which can be applied with real time ITS services to adapt changes in the integrity status of the navigation system. Context-aware architecture is designed to collect contextual information about the vehicle, including location, speed and heading, reasoning about its integrity and reactions based on the information acquired. In this research, three phases of integrity checks are developed. These are, (i) positioning integrity, (ii) speed integrity, and (iii) map matching integrity. Each phase uses different techniques to examine the consistency of the GPS information. A receiver autonomous integrity monitoring (RAIM) algorithm is used to measure the quality of the GPS positioning data. GPS Doppler information is used to check the integrity of vehicle’s speed, adding a new layer of integrity and improving the performance of the map matching process. The final phase in the integrity algorithm is intended to verify the integrity of the map matching process. In this phase, fuzzy logic is also used to measure the integrity level, which guarantees the validity and integrity of the map matching results. This algorithm is implemented successfully, examined using real field data. In addition, a true reference vehicle is used to determine the reliability and validity of the output. The results show that the new integrity algorithm has the capability to support a various types of location-based ITS services.

International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / This paper introduces the frequency spectrum characteristic of FM radio broadcast and the message format of RBDS (Radio Broadcast Data System). DGPS correction message in RBDS is described in detail. A design method of RBDS/DGPS system is proposed and the RBDS/DGPS system developed by us is introduced. Finally, some special advantages of RBDS/DGPS system are given.

International Telemetering Conference Proceedings / October 23-26, 2000 / Town & Country Hotel and Conference Center, San Diego, California / Global Positioning System (GPS) technology is being used as a sensor in telemetry systems to provide time, space and position information (TSPI) as well as end game or vector scoring. The accuracy of these measurements depends on precisely locating the phase center of the GPS antenna. A procedure has not currently been addressed by anyone to measure the phase center of a conformal wrap-around GPS antenna. This paper will discuss some techniques on determining the antenna phase center.

International Telemetering Conference Proceedings / October 21, 2002 / Town & Country Hotel and Conference Center, San Diego, California / The Joint Advanced Missile Instrumentation (JAMI) program is integrating Global Positioning System (GPS) technology into missile telemetry systems. The weakest link appears to be the GPS antenna. The antenna on a missile is required to be flush mounted for aerodynamic reasons. Due to the missile’s tendency to roll, the antenna needs to be a multi-element omnidirectional antenna array. Therefore an antenna used on missiles is a wrap-around antenna since it will meet the flush mount and rolling requirements by giving omnidirectional coverage. JAMI has used readily available techniques for designing wrap-around telemetry antennas to develop a GPS wrap-around antenna and has discovered a major problem. The Phase Center of a wrap-around antenna tends to be a surface, not a point, and not necessarily at the centerline of the missile body. GPS measurements have been conducted to determine the Phase Center of the antenna. When the Phase Center is large, the GPS receiver perceives it as multipath and integer ambiguities cannot be resolved. This paper addresses the problems that have been uncovered and outlines the steps that are planned to resolve them.

International Telemetering Conference Proceedings / October 21, 2002 / Town & Country Hotel and Conference Center, San Diego, California / The intelligent vehicle navigation system is the multifunctional and complex integrate system that involved in auto positioning technology, geography information system and digital map database, computer technology, multimedia and wireless communication technology. In this paper, the autonomous navigation system based on the embedded hardware and embedded software platform is proposed. The system has advantages of low cost, low power consumption, multifunction and high stability and reliability.

International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The U.S. Air Force has developed GPS-based instrumentation systems to support both test and training activities. In support of recent large-scale exercises, interfaces were developed to employ existing test and training assets in a synthetic battlefield. The writers propose exploration of similar approaches to overcome the challenge of developing a common approach to test and training instrumentation.

published_or_final_version / abstract / Electrical and Electronic Engineering / Master / Master of Philosophy

The focus of this validation study is to develop and use Global Positioning System (GPS) technology as a tool for psychological research. GPS technology was used to estimate the number of places participants visited over a four day period. To test the convergent validity of this method, this estimate was compared to two self-report methods of measuring the same behavior over the same time frame. All three of these methods were significantly correlated with each other. Results of the split-plot GLM further validated the convergent validity of the GPS method. The test of construct validity was successful when it comes to covitality, however, negative affect did not predict NPV.

Complex defense acquisition programs, such as the Global Positioning System program, have many requirements engineering challenges to overcome in order to deliver capabilities to customers and satisfy other stakeholders. To meet these challenges and stay within cost and schedule constraints, engineers and managers need system requirements information organized in a clear, complete, and efficient manner to support decision making. An effective methodology tailored to the needs of the program decision makers will ensure that important information is correct, organized, and readily accessible. The GPS program is implementing a methodology that includes standardized processes across its segments. However, the GPS program refrained from implementing a better requirements engineering approach and using its current requirements engineering tool to take advantage of this approach.

São inúmeras as atividades que fazem uso do sistema Global Navigation Satellite System - GNSS, sendo o Global Positioning System - GPS, desenvolvido pelos Estados Unidos, o mais utilizado. Na área de agricultura de precisão há a necessidade de posicionamento estático e cinemático com demandas de distintos níveis de acurácia e precisão para diferentes aplicações. A deficiência de informações técnicas dos fabricantes causa incertezas nos usuários, quanto à classe de receptor a ser utilizado para determinadas atividades agrícolas. Por esses motivos os objetivos deste trabalho foram: avaliar o uso de correções diferenciais através de ensaio estático, testar o uso do receptor GPS RTK como referência para avaliar o desempenho de receptores de baixo custo em condição cinemática e desenvolver uma plataforma instrumentada para avaliar os receptores de GPS sob condição cinemática representativa para operações agrícolas. No primeiro caso foram realizados ensaios com oito receptores, sobre uma torre livre de impedimentos físicos, na qual foi montada uma plataforma em formato de cruz e nos receptores foram ativadas e desativadas as correções diferenciais WAAS, EGNOS, SF1 e SF2 e também testadas as várias intensidades de filtragem disponíveis em alguns dos receptores. No ensaio cinemático utilizando um receptor GPS RTK como referência foram utilizados dois receptores de navegação, fixados sobre a cabine de um trator e foram coletados dados com diferentes freqüências. Para ensaios cinemáticos foi construída uma plataforma móvel instrumentada com um detector óptico de pulsos (encoder), um sensor foto elétrico e dois coletores de dados responsáveis por realizar o sincronismo entre os pulsos do encoder e as atualizações da sentença do GPS e armazenamento dos dados. Assim foi possível determinar as coordenadas de referência para o cálculo dos erros de precisão e acurácia do receptor GPS submetido à avaliação. Na avaliação dos receptores em ensaio estático os resultados mostraram que as correções WAAS e EGNOS não adicionam qualidade ao posicionamento na região de Piracicaba, SP. Com a ativação dessas correções os erros de precisão e de acurácia aumentaram. As correções diferencias SF1 e SF2 via satélite demonstraram ser mais acuradas que os demais sistemas ensaiados. O ensaio sob condição cinemática, com GPS RTK de referência, permitiu o cálculo de erros somente no sentido perpendicular ao percurso. A plataforma instrumentada funcionou, cumprindo as expectativas e permitindo o cálculo dos erros de precisão e acurácia, porém demonstrou problemas de robustez nos coletores de dados, necessitando de pequenas melhorias. / The activities that use the Global Navigation Satellite System - GNSS, are countless, and the Global Positioning System - GPS, developed by the United States is the most used today. In precision agriculture there is a need of static and cinematic positioning with demands of distinct levels of accuracy and precision for different applications. Technical information deficiencies from the manufacturers causes uncertainties to the users, as the receiver class to be used for certain agricultural activities. For these reasons the objectives of this work were: evaluate the use of differential corrections through static test, to test the use of RTK GPS as reference to evaluate the performance of low cost receivers under cinematic condition and develop an instrumented platform to evaluate GPS receivers under cinematic condition that represents agricultural operations. In the first case were realized tests with eight receivers, in the top of a tower free of physical obstacles, where it was mounted a platform with cross shape. The differential corrections WAAS, EGNOS, SF1 and SF2 were tested and also some intensities of filtering available in some of the receivers. In one of the cinematic tests, using a RTK GPS as reference, we used two navigation receivers, fixed over a tractor cabin and the data were collected with different frequencies. For the second cinematic test it was built a moving platform instrumented with a pulse optical detector (encoder), a photoelectric sensor and two data loggers, responsible for the synchronization between the encoder pulses and the GPS strings, and also log the data. With that it was possible to determine the reference coordinates to calculate the errors of precision and accuracy of the GPS receiver submitted to evaluation. The evaluation in static way showed that the corrections WAAS and EGNOS do not work in the region of Piracicaba, SP. Activating these corrections the precision and accuracy errors increased. The data collected with the satellite differential corrections SF1 and SF2 got closer to the real coordinate than the other evaluated systems. The test under cinematic condition, with the RTK GPS as reference, allowed the errors calculation only in the perpendicular direction of the course. The instrumented platform worked, accomplishing the expectation and allowing the errors calculation of precision and accuracy, however, showed problems of robustness in the data loggers, needing some improvement.