Thesis (MScIng)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: The purpose of this study was to develop a Global Positioning System (GPS) receiver for use on a Low-Earth Orbit (LEO) satellite. The study includes an examination of some of the fundamental GPS theory and how the LEO environment affects the operation of a GPS receiver. The hardware and software that was selected for the implementation are discussed. The reasons for porting the software to a new hardware platform and methods employed in the port are given. Thereafter the process of adapting the receiver software for use in space is given. To verify the operation in space, the receiver was subjected to LEO simulations using a GPS signal simulator. These results are shown and discussed. The tests indicated that the adaptations were successful and that the receiver will function on a LEO satellite. / AFRIKAANSE OPSOMMING: Die doel van die tesis was om ’n Globale Posisionerings Stelsel (GPS) ontvanger to ontwikkel vir gebruik op ’n lae-wentelbaan satelliet. Die studie begin met fundamentele GPS teorie en hoe die funksionering van die ontvanger be¨ınvloed word deur die wentelbaan van ’n satelliet. Die hardeware en sagteware vir die implementasie word bespreek. Die rede en metodes om die sagteware aan te pas om te werk op nuwe hardeware word gegee. Daarna word die proses om die sagteware aan te pas vir ruimtegebruik gegee. Om the verifieer dat die ontvanger wel sal kan werk op ’n satelliet was dit getoets in ’n gesimuleerde ruimte-omgewing met ’n GPS seinsimulator. Hierdie resultate word gegee en bespreek. Die toetse het gewys dat die aanpassings suksesvol was en dat die ontvanger in die ruimte sal funksioneer.

Unmanned ground mobile robots are land-based robots which do not have a human passenger on board. They can be either autonomous, or controlled via telecommunication. For navigational purposes, GPS is often used. However, the GPS signal can be distorted in obstructive environments such as tunnels, urban canyons, and dense forests. IMUs can be used to provide an internal navigational solution, free from external input. However, low cost IMUs are prone to various intrinsic sources of error, which leads to large errors in the long run. Using the short term accuracy of the IMU, and the long term accuracy of the GPS, these two technologies are often integrated to combine the aforementioned aspects of the two systems. For integration of the two, various methods are implemented. Such integration methods include Particle Filters, and Kalman Filters. Kalman Filters are commonly used due to their simplicity in calculations. However, the Kalman Filter linearizes the nonlinear error estimates which are inherent with low cost IMUs. The Kalman Filter also does not account for IMU measurement drift, which is present when the measurement unit is used for a long period of time. In this thesis, a Parallel Cascade Identification (PCI) algorithm is augmented with the Kalman Filter (KF) to model the nonlinear errors which are intrinsic to the low cost IMU. The method of integration used was 2D GPS/RISS loosely coupled integration using a Kalman Filter. The PCI algorithm modelled the nonlinear error for the z-axis gyroscope while the GPS signal was available. During a GPS outage, the PCI nonlinear error model was combined with the KF estimated error and the mechanization error, to provide a corrected azimuth. The KFPCI algorithm showed an improvement over the KF algorithm in RMS position error, maximum position error, RMS azimuth error, and maximum azimuth error by an average of 30.76%, 34.71%, 66.76%, and 53.58% in each of the respective areas. / Thesis (Master, Electrical & Computer Engineering) -- Queen's University, 2013-06-11 18:13:12.625

U.S. Army Corps of Engineers (USACE) regulates fill of jurisdictional waters of the United States including wetlands. Recent USACE regulations set a threshold of impacts to wetlands at one-half acre. Impact area can be determined by Global Positioning System (GPS) measurement of wetland boundary and Geographic Information System (GIS) calculation of impact area. GPS point selection methods include (1) equal time interval, (2) transect and (3) intuition. Four two-acre shapes were measured with each GPS method and brought into GIS for area calculation. Analysis of variance and Root Mean Square Error analyses determine that the transect method is an inferior point selection method in terms of accuracy and efficiency.

International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, Nevada / GPS user equipment has matured and is now available to support the use of live players in integrated ranges and simulations. P-code GPS provides true WGS-84 based coordinate information anywhere in the world at any time and to accuracies at the 5 ft (1s) level (demonstrated in high dynamic aircraft using differential P-code GPS). C/A code GPS shows lower accuracy and is especially vulnerable to multipath degradation over water. In supporting networked ranges with simulations, GPS is directly applicable to the dead reckoning requirements of the Distributed Interactive Simulation (DIS) community. DIS dead reckoning provides the capability of much reduced data rates in recovering TSPI information from platforms. The on-board state vector for an integrated GPS/Inertial Reference Unit provides accurate position, velocity and acceleration as well as attitude and attitude rate information so that dead reckoning thresholds can be both position and attitude driven. A simplified analysis is presented in the paper to derive dead reckoning update rates from the G loading levels of various player dynamics. Also, information is provided which results in word length requirements for GPS-based state vector information for transmission over minimum word length DIS Field Instrumentation Protocol Data Units (PDUs, which are the data block formats). The coordinate frame problem in use of GPS-based state vector information from fixed ranges is also addressed, showing that the use of a local geodetic frame is preferable to the use of an earth centered earth fixed frame, in that it is more efficient of network PDU word length.

The Deployable Navigation System (DeNS) is a prototype system designed to facilitate Command and Control during over the horizon small boat operations. It is designed to allow small boats to deploy from their host ships with a Bluetooth GPS (Global Positioning System) receiver and PDA (Personal Digital Assistant) running the appropriate software which provides a real time navigational picture in terms of position and relation to a predetermined track. This same data is shipped immediately back to the control ship via a wireless network and displayed on a laptop computer to allow the mission commander to monitor the small boatâ s progress and position, also in real time. The small boatâ s relation to the track is compared on every received fix and appropriate indicators are displayed to inform both users if a predetermined distance from track (track tolerance) has been exceeded. It utilizes jpg formatted maps that are derived directly from the Digital Nautical Chart (DNC) library overlaid with track information. Positions received from the GPS are converted to pixel coordinates that correspond to their original positions on the jpg chart and plotted, providing an electronic display that is very similar in appearance to the traditional plot maintained on paper charts.

M.Ing. / The increase of interest in the development of radio communications, both terrestrial and satellite is reaching far and beyond the most optimistic expectations. There has been an accelerated emergence of newer technologies, all claiming highly coveted radio frequency spectrum resources. With the push for the development of location based services, utilizing satellite com- communications for military purposes and later for civilian use; there has been a parallel development in terrestrial communications technology making it possible to implement cost efficient reliable user systems for voice and data services ...

M. Tech. (Engineering: Electrical; Department of Electronic Engineering, Faculty of Engineering and Technology )-- Vaal University of Technology / In the ever growing sport of model aircraft, pilots are challenged with many obstacles. In the division of gliders, one of the biggest problems is the loss of model aircraft. Pilots launch their aircraft off mountain tops and if the aircraft crashes below, the pilot must make use of his best estimates in order to locate the aircraft. This either takes several hours, or the aircraft is never recovered. Pilots are also at a loss with regard to real time data, such as, but not limited to, battery levels, fuel levels, altitude and speed. Model aircraft competitions are also limited to the best estimate of officials. In this work an attempt has been made to design and develop a remote tracking device for model aircraft. This device will retrieve Global Positioning System (GPS) co-ordinates from the aircraft and relay them to the pilot on the ground. In the event of a crash, the pilot will retrieve the last GPS co-ordinates and then proceed to the location to collect the aircraft. An attempt will also be made to design add-on telemetry components that will allow for measurement and transmission of battery levels, fuel levels, altitude, G-Force, orientation, acceleration, wind and ground speed. Some of the data retrieved from the Flight Data Recorder (FDR) in trial 1 are: maximum altitude above sea level of 2139.20 m, maximum speed over ground which was 57.34 m/s and the average battery voltage for transceiver and servos was 15.2 v.

Climate change is a very current and contentious issue that has received a lot of attention during the past two decades because of its global influence and impact. Climate change affects the entire globe and the impact is mostly continental and regional and is not limited along state borders. Whether a person or group believe in the existence of global warming or not, the scientific evidence leaves no doubt that the climate is changing (Mazo, 2010: 9). Climate change influence the environment people live in and have a direct impact on all aspects of their daily lives. In a globalized world almost all problems cross borders, and environmental issues have long been recognized as among the most international and the most transnational of all (Parsons, 2009: 5). Climate change acts as a “threat multiplier” by exacerbating existing vulnerabilities, and must be analysed in relation to the adaptive capacity of those affected (individuals, communities and states), taking account of the wider political, socio-economic and demographic context (ACCES, 2011: 9). Although climate change has a global impact, the African continent is likely to be more severely affected than other regions of the globe and it will have a profound negative impact on all facets of human security. Long-term shifts in the climate seem likely to catalyse conflict by creating or exacerbating food, water and energy scarcities, triggering population movements, and placing larger groups of people in competition for more and more limited resources. Increased climate variability, including the greater frequency of extreme weather events, will also complicate access to resources, thereby exacerbating conditions that are conducive to promoting conflict. Southern Africa is described as a predominantly semi-arid region with high intra- seasonal and inter-annual rainfall variability, with extreme events such as droughts and floods occurring frequently. In Southern Africa, there has been an increase in inter-annual variability of rainfall over the past 40 years, with more intense and widespread droughts. Floods and droughts in Southern Africa are gradually increasing in number and frequency as well and already the entire region is considered a climate change "hotspot". As can be seen from the findings of the various chapters, climate change has a very complex predicted impact on all the dimensions of human security and a few major key issues in this regard came to light. These issues include urbanisation, migration, environmental degradation and biodiversity loss, water scarcity, spread of diseases, slow onset climate change, economic decline and poverty, criminality and conflict. The most profound issues that will have an impact on South African border integrity and safeguarding include urbanisation, migration, environmental degradation and biodiversity loss, water scarcity, spread of diseases, economic decline and poverty, criminality and conflict. Migration can be singularly highlighted as it has the potential to amplify and exacerbate all of the abovementioned issues. States have national security strategies and policies in order to guide policy and legislation to adequately protect the state from threats and to determine national security priorities. Border safeguarding is an important aspect of state security and strategy, policy and legislation, informed by the national security strategy and policy, constantly have to evolve and adapt to changes in the threat pattern affecting states. The border safeguarding environment of any state is very complex and faced with multiple external and international threats. Climate change-related human security threats will further amplify and complicate these threats as the impact of climate change becomes more pronounced in the southern African region. In order for South Africa to successfully address these threats in the border safeguarding environment it is important that a sound National Security Strategy and Policy provide focus and priorities for all government departments involved. This is a very complex field with multiple factors and only the key issues are highlighted and discussed in this paper.

Atualmente observa-se um aumento significativo do uso de sistemas eletrônicos no maquinário agrícola, proporcionando melhora significativa na eficiência em campo e melhores rendimentos operacionais. Na aplicação de produtos fitossanitários, a utilização de equipamentos que controlam automaticamente as seções da barra e a pulverização já é realidade, entretanto ainda não há resultados que demonstrem a sua eficácia. Por esse motivo, este trabalho teve por finalidade desenvolver uma metodologia para a avaliação de um equipamento comercial que controla automaticamente as seções da barra de pulverizadores e a pulverização. Para a avaliação do controlador foram utilizados três níveis de acurácia do sinal de GPS (Firmware, VBS e RTK), três ângulos para a simulação de entrada e saída da barra de pulverização em relação a borda do talhão (0, 45 e 60°) e três velocidades de trabalho ( 1,66, 5,00 e 8,33 m s-1). O pulverizador autopropelido foi instrumentado com diversos sensores a fim de se determinar os tempos de abertura ou fechamento das seções da sua barra de pulverização em relação à linha delimitadora da borda do talhão. O controlador automático de seção e pulverização avaliado foi o AgGPS® EZBoom Trimble, modelo 2010, montado em um pulverizador autopropelido da marca comercial UNIPORT 2500 STAR®. A metodologia proposta possibilitou a determinação dos tempos para a abertura e fechamento das válvulas de acionamento elétrico das seções. Os coeficientes de variação calculados para os tempos e distâncias de abertura e fechamento das válvulas de acionamento elétrico, e início ou término da pulverização, indicaram uma variação considerável entre os valores para as diferentes repetições, sendo mais expressivos nos tratamentos com simulação de entrada e saída da barra de pulverização em ângulos de 45 e 60°. Foram identificadas algumas interações significativas em função do tipo de sinal GPS utilizado, entretanto, não se pode dizer qual foi o melhor sinal de GPS no âmbito geral. As interações entre as diferentes velocidades e ângulos, tendem a aumentar a variação dos tempos e distâncias de início e término da pulverização. A configuração recomendada pelo fabricante e adotada para a avaliação do controlador automático de seções e pulverização, não atende a todas as situações simuladas, sendo necessária para cada velocidade uma configuração específica, a fim de se reduzir o início prematuro, falhas e sobreposições excessivas durante a pulverização. / Currently there is a significant increase in the use of electronic systems in agricultural machinery, providing significant improvement in field efficiency. In the application of pesticides, the use of equipment that automatically controls the sections of the boom and the spray is already reality. However there are no results to show its effectiveness. Therefore, this work was to develop a methodology for the evaluation of commercial equipment which automatically controls the sections of the boom and the spraying. For the evaluation of the controller were used three levels of GPS accuracy signal (Firmware, VBS and RTK), three angles for the simulation of entrance and exit of the spray boom crossing the field boundary (0, 45 and 60 °) and three working speeds (1.66, 5.00 and 8.33 m s-1). The self-propelled sprayer was instrumented with various sensors in order to determine the time of opening or closing sections of the spray boom when crossing the field boundary. The automatic boom section and spraying controller evaluated was an AgGPS® EZ-Boom Trimble, model 2010, mounted on a self-propelled sprayer Uniport 2500 STAR®. The proposed methodology allowed the determination of opening and closing times of the electric valves. The coefficients of variation calculated for the times and distances of opening and closing the electric valves, and start or stop spraying, indicated a considerable variation among the values for the different replications, and more significant in the treatments with simulation of entrance and exit of the boom at angles of 45 and 60°. Significant interactions have been identified depending on the type of GPS signal used, however, it cannot be said what was the best GPS signal. The interactions between different speeds and angles, tend to increase the variation in times and distances of the start and stop spraying. The recommended configuration by the manufacturer, used for the evaluation of the automatic boom sections and spraying controller, does not meet all the simulated situations, being required a specific configuration for each speed in order to reduce gaps and overlaps in the spraying.

Yu Sheung Fan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2003. / Includes bibliographical references (leaves 96-99). / Abstracts in English and Chinese. / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Background: Context-Aware Applications --- p.2 / Chapter 1.1.1 --- Definitions of Context --- p.2 / Chapter 1.1.2 --- Existing Applications --- p.3 / Chapter 1.1.3 --- Review --- p.6 / Chapter 1.2 --- Research Motivation --- p.6 / Chapter 1.3 --- Research Contributions --- p.8 / Chapter 1.4 --- Thesis Outline --- p.8 / Chapter 2. --- Location-sensing Technologies --- p.9 / Chapter 2.1 --- Global Positioning System (GPS) --- p.9 / Chapter 2.2 --- Existing indoor Location-sensing Systems --- p.11 / Chapter 2.2.1 --- Active Badge --- p.11 / Chapter 2.2.2 --- The Bat System --- p.12 / Chapter 2.2.3 --- RADAR --- p.13 / Chapter 2.2.4 --- PinPoint 3D-iD --- p.14 / Chapter 2.2.5 --- Easy Living --- p.15 / Chapter 2.3 --- System Properties and Risks --- p.16 / Chapter 2.3.1 --- Accuracy --- p.17 / Chapter 2.3.2 --- Cost --- p.18 / Chapter 2.3.3 --- User Privacy --- p.18 / Chapter 2.3.4 --- Location Representation --- p.19 / Chapter 2.3.5 --- Other Limitations --- p.20 / Chapter 2.4 --- Design Goals --- p.20 / Chapter 2.4.1 --- Operate Inside Buildings --- p.21 / Chapter 2.4.2 --- Preserve User Privacy --- p.21 / Chapter 2.4.3 --- Low Cost --- p.22 / Chapter 2.4.4 --- Fast Response --- p.22 / Chapter 2.4.5 --- Spatial Recognition --- p.23 / Chapter 2.4.6 --- Easy Administration and Deployment --- p.23 / Chapter 2.5 --- Summary --- p.23 / Chapter 3. --- System Design --- p.25 / Chapter 3.1 --- System Architecture --- p.25 / Chapter 3.2 --- Position-sensing Platform --- p.28 / Chapter 3.2.1 --- Platform Architecture --- p.29 / Chapter 3.2.2 --- Transmission Format --- p.30 / Chapter 3.2.3 --- Distance Measurement --- p.31 / Chapter 3.2.4 --- Position Estimation --- p.32 / Chapter 3.2.5 --- Noise Cancellation --- p.35 / Chapter 3.2.6 --- Location Inference --- p.36 / Chapter 3.3 --- Summary --- p.38 / Chapter 4. --- System Implementation --- p.39 / Chapter 4.1 --- Communication Technologies --- p.39 / Chapter 4.1.1 --- Ultrasound --- p.40 / Chapter 4.1.2 --- Radio Frequency Identification (RFID) --- p.40 / Chapter 4.1.3 --- Infrared Data Association (IrDA) --- p.41 / Chapter 4.1.4 --- Bluetooth --- p.42 / Chapter 4.2 --- Technologies Overview --- p.43 / Chapter 4.2.1 --- Positioning --- p.44 / Chapter 4.2.2 --- Networking --- p.44 / Chapter 4.2.3 --- Communication Protocol --- p.45 / Chapter 4.2.4 --- Range --- p.45 / Chapter 4.2.5 --- Angle Dependency --- p.45 / Chapter 4.2.6 --- Hardware supports --- p.46 / Chapter 4.3 --- Hardware --- p.46 / Chapter 4.3.1 --- Mobile Receiver --- p.46 / Chapter 4.3.2 --- Transmitter --- p.47 / Chapter 4.4 --- Software --- p.47 / Chapter 4.4.1 --- Communication Protocol --- p.48 / Chapter 4.4.2 --- Programming Environment --- p.48 / Chapter 4.4.3 --- Signal Generation Routine --- p.48 / Chapter 4.4.4 --- Position Estimation Routine --- p.50 / Chapter 4.5 --- Summary --- p.53 / Chapter 5. --- Evaluation --- p.55 / Chapter 5.1 --- Platform Calibration --- p.55 / Chapter 5.1.1 --- Outliers Elimination --- p.56 / Chapter 5.1.2 --- Delay Determination --- p.58 / Chapter 5.1.3 --- Window Size Determination --- p.61 / Chapter 5.1.4 --- Revised Position Estimation Algorithm --- p.63 / Chapter 5.2 --- Platform Evaluation - IrDA Figure 5.9: Experimental setup for distance performance evaluation --- p.64 / Chapter 5.2.1 --- Distance Measurement Figure 5.10: IrDA horizontal distance measurement experiment results --- p.66 / Chapter 5.2.2 --- Position Estimation - Static --- p.66 / Chapter 5.2.3 --- Position Estimation - Mobile --- p.68 / Chapter 5.3 --- Platform Evaluation - Bluetooth --- p.69 / Chapter 5.3.1 --- Distance Measurement --- p.69 / Chapter 5.3.2 --- Position Estimation - Static --- p.70 / Chapter 5.3.3 --- Position Estimation ´ؤ Mobile --- p.71 / Chapter 5.4 --- Summary --- p.73 / Chapter 6. --- Applications --- p.74 / Chapter 6.1 --- Potential Applications --- p.74 / Chapter 6.1.1 --- Resource Tracking Systems --- p.75 / Chapter 6.1.2 --- Shopping Assistance System --- p.76 / Chapter 6.1.3 --- Doctor Tracking System --- p.77 / Chapter 6.1.4 --- Tourist Guide Application --- p.78 / Chapter 6.1.5 --- Other Applications --- p.79 / Chapter 6.2 --- System Limitations --- p.79 / Chapter 6.3 --- Summary --- p.79 / Chapter 7. --- Conclusion --- p.80 / Chapter 7.1 --- Summary --- p.80 / Chapter 7.2 --- Future Work --- p.81 / Chapter Appendix A: --- IrDA --- p.86 / Chapter A.1 --- IrDA Physical Layer --- p.86 / Chapter A.2 --- Physical Aspects of IrDA Physical Layer --- p.87 / Chapter A.3 --- Discovering Other IrDA Devices --- p.88 / Chapter A.4 --- Connection of IrDA Devices --- p.89 / Chapter Appendix B: --- Bluetooth --- p.91 / Chapter B.1 --- Bluetooth Stack --- p.91 / Chapter B.2 --- Radio --- p.92 / Chapter B.3 --- Frequency Hopping --- p.92 / Chapter B.4 --- Package Structure --- p.92 / Chapter B.5 --- The Link Controller --- p.93 / Chapter B.6 --- The Link Manager --- p.93 / Chapter B.7 --- Logical Link Control and Adaptation Protocol --- p.94 / Chapter B.8 --- The Service Discovery Protocol --- p.94 / Chapter B.9 --- Encryption and Security --- p.95 / Bibliography --- p.96