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.

This thesis is executed in cooperation with RUAG Space AB, which specializes in highly reliable on-board satellite equipment. The thesis focuses on the effect, which disturbs the amplitude and phase of a Global Positioning System (GPS) signal, called scintillation effect. It has a substantial impact on a GPS signal, during Radio Occultation (RO). RO is a method of analysis of a refracted signal which passes through the atmosphere. RO can be used for measuring climate change and for weather forecasting. By retrieving the bending angle of a GPS signal, three basic parameters of the Earth’s atmosphere can be obtained at different heights: temperature, pressure and humidity. As the scintillation effect causes prominent errors in the bending angle calculations, it is crucial to provide possibly the most precise mathematical model, which allows to conceive proper ionospheric corrections. In this thesis, the model using Rytov approach is implemented and optimised with different optimisation functions. It is shown that the scintillation model can be optimized, which may contribute to a more accurate retrieval of the atmospheric profiles.

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.