Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Location and tracking of personnel and assets is a lucrative enterprise that has seen much expansion in the last decade or two. This expansion is coupled with the rise in popularity of GPS-based technologies. It has become common practice for businesses to track and manage vehicle fleets with GPS enabled devices. We use GPS to navigate while driving our cars, to keep track of our loved ones and we even have GPS receivers in our cell phones. Unfortunately, GPS technology has a few limitations. It can only be used in areas with a clear view of the sky, as line-of-sight must be maintained with at least four satellites at all times. This precludes the use of GPS indoors or in heavily built-up areas. GPS receivers are also still quite expensive. This thesis developed and implemented a strategy for Localised Position Location. Several possible solutions were investigated. Spread Spectrum was selected as the best method to develop into a working example. The characteristics of Spread Spectrum signals and Pseudo-Noise Codes were investigated in some detail, which led to the proposal of several simulation models. These simulations suggested that a simple configuration consisting of a transmitter, sliding correlator, bandpass filter and RF power detector can effectively track a stationary target. A transmitter was designed and implemented and was then used in a simplified measurement to corroborate the predictions made by earlier simulations. With results looking positive it was decided to continue with the design and implementation of a receiver. A complete transmitter/receiver system allowed for extensive measurements to be made. The physical measurements agreed with simulated predictions, confirming that the proposed position location strategy is effective. / AFRIKAANSE OPSOMMING: Die toenemende gewildheid en toeganklikheid van GPS-gebaseerde opsporingstegnologie het gelei tot ‘n geweldige toename in die verkope van toerusting om die beweging van besigheidsbates te monitor en bestuur. Selfs op die persoonlike ontspanningsmark vind GPS-tegnologie toenemend aanklank met vervaardigers van selfone en voertuignavigasietoerusting. GPS-gebaseerde opsporingstegnologie het egter beperkinge, omdat dit te alle tye direkte oogkontak moet behou met minstens vier satelliete. Gevolglik kan GPS-gebaseerde opsporingstegnologie nie binnenshuis of in erg beboude gebiede gebruik word nie. GPS ontvangers is ook redelik duur. Hierdie thesis het `n strategie vir Gelokaliseerde Posisie Bepaling ontwikkel en geïmplementeer. Ondersoek is ingestel na `n verskeidenheid van moontlike oplossings. Strek Spektrum is gekies as die beste metode om verder in `n werkende voorbeeld te ontwikkel. Die eienskappe van Strek Spektrum seine en Pseudo-Ruis Kodes is in detail bestudeer, wat gelei het na die opstelling van `n aantal simulasie modelle. Hierdie modelle dui aan dat `n eenvoudige opstelling, bestaande uit `n sender, glykorellator, banddeurlaat filter en `n RF drywingsmeter doeltreffend aangewend kan word om `n stilstaande teiken te monitor. `n Sender, wat in `n vereenvoudigde meetopstelling gebruik kon word om van die voorspellings wat vroeër gemaak is te staaf, is hierna ontwerp en gebou. Met positiewe resultate is daar besluit om voort te gaan met die ontwerp en bou van `n ontvanger. Met `n volledige sender/onvanger stelsel was dit moontlik om uitgebreide meetings te neem. Die fisiese meetings stem ooreen met die simulasies se voorspellings, wat dien as bevestiging dat die voorgestelde strategie vir posisie bepaling doeltreffend aangewend kan word.

International Telemetering Conference Proceedings / October 28-31, 1985 / Riviera Hotel, Las Vegas, Nevada / Demonstration results are presented for a high dynamic GPS receiver. The receiver tested is a breadboard unit capable of tracking one simulated satellite signal in pseudorange and range rate. The receiver makes approximate maximum likelihood estimates of pseudorange and range rate each 20 ms, and tracks these observables using a third order filter with a time constant of 0.14 s. Carrier phase is not tracked, which eliminates the typical failure mode of loss of carrier lock associated with PLLs at high dynamics. The receiver tracks with pseudorange lag errors of under 0.06 m when subjected to simulated 50 g turns with 40 g/s peak jerk. Pseudorange errors due to receiver noise alone are approximately 0.6 m rms at a carrier power to noise spectral density ratio of 34 dB-Hz. The tracking threshold SNR is approximately 28 dB-Hz, which provides 12 dB margin relative to the 40 dB-Hz that occurs with minimum specified satellite signal strength, 3.5 dB system noise figure, and 0 dBi antenna gain.

International Telemetering Conference Proceedings / October 22-25, 1984 / Riviera Hotel, Las Vegas, Nevada / A breadboard high dynamic GPS receiver capable of pseudorange tracking with accelerations of 50 g or higher without inertial aiding is presented. The receiver uses cross correlation followed by fast Fourier transformation to approximate maximum likelihood estimation of pseudorange and range rate, with no phase or delay locked loops. The breadboard system consists of a one channel receiver and a high dynamics signal simulator. A planned demonstration of the receiver is described and anticipated results are presented showing pseudorange lag errors of under 10 m with acceleration of 50 g.

International Telemetering Conference Proceedings / October 21, 2002 / Town & Country Hotel and Conference Center, San Diego, California / The objective of the project is to continuously track a handheld device in an office, with centimeter accuracy in the three dimensions. A 3-D ray-tracing algorithm has been developed to simulate the impulse response of the indoor channel. The algorithm can evaluate the impulse response at multiple receiver locations. Non-linear optimization has been used to eliminate the need for multiple runs of simulation. The optimization program also significantly reduces the number of rays launched. The algorithm incorporates bandwidth effects on multipath resolution of the system.

This thesis analyzes the use of hidden Markov models (HMM) in wireless communication systems. HMMs are a probabilistic method which is useful for discrete channel modeling. The simulations done in the thesis verified a previously formulated methodology. Power delay profiles (PDP) of twelve wireless receivers were used for the experiment. To reduce the computational burden, binary HMMs were used. The PDP measurements were sampled to identify static receivers and grid-based analysis. This work is significant as it has been performed in a new environment. Stochastic game theory is analyzed to gain insight into the decision-making process of HMMs. Study of game theory is significant because it analyzes rational decisions in detail by attaching risk and reward to every possibility. Network security situation awareness has emerged as a novel application of HMMs in wireless networking. The dually stochastic nature of HMMs is applied in this process for behavioral analysis of network intrusion. The similarity of HMMs to artificial neural networks makes it useful for such applications. This application was performed using simulations similar to the original works. / Master of Science

Radio frequency system optimization and troubleshooting remains one of the most challenging aspects of working in a cellular network. To stay competitive, cellular providers continually monitor the performance of their networks and use this information to determine where to improve or expand services. As a result, operators are saddled with the task of wading through overwhelmingly large amounts of data in order to trouble-shoot system problems. Part of the difficulty of this task is that for many complicated problems such as hand-off failure, clues about the cause of the failure are hidden deep within the statistics of underlying dynamic physical phenomena like fading, shadowing, and interference. In this research we propose that Hidden Markov Models (HMMs) be used as a method to infer signature statistics about the nature and sources of faults in a cellular system by fitting models to various time-series data measured throughout the network. By including HMMs in the network management tool, a provider can explore the statistical relationships between channel dynamics endemic to a cell and its resulting performance. This research effort also includes a new distance measure between a pair of HMMs that approximates the Kullback-Leibler divergence (KLD). Since there is no closed-form solution to calculate the KLD between the HMMs, the proposed analytical expression is very useful in classification and identification problems. A novel HMM based position location technique has been introduced that may be very useful for applications involving cognitive radios. / Ph. D.

Effective construction management involves real-time decisions regarding the progress of specific activities, the location of materials and equipment, and the construction site safety. The decision making process can be improved using real-time positioning technologies such as Radio Frequency Identification Device (RFID) systems, Global Positioning System (GPS), and Ultra Wide Band (UWB) sensors. While the GPS is not applicable to indoor positioning and RFID tags cannot provide a fully automated system for position location, the characteristics of UWB systems make this technology a strong candidate for a fully automated positioning system in an indoor construction environment. This thesis presents a comprehensive study of the performance of UWB systems in a controlled laboratory environment and in an institutional construction site in Waterloo, Canada as well as for a particular safety application. A primary objective of the research was to establish the accuracy of real-time position location under various conditions, including the effect of different construction materials (e.g., wood and metal), and to analyze changes in the accuracy of position location as construction progresses and the indoor environment physically evolves. Different challenges faced in implementing such a system in an active construction environment are addressed. Based on a statistical analysis of laboratory data, and considering the construction site experience, the reliability of the UWB positioning system for the aforementioned environments is discussed. Furthermore, an automated safety system is proposed using the real-time UWB positioning technology. Based on the error modeling of the UWB position location, an optimum alarming algorithm is designed for the proposed safety system and the reliability of such system is evaluated through a statistical analysis.

Effective construction management involves real-time decisions regarding the progress of specific activities, the location of materials and equipment, and the construction site safety. The decision making process can be improved using real-time positioning technologies such as Radio Frequency Identification Device (RFID) systems, Global Positioning System (GPS), and Ultra Wide Band (UWB) sensors. While the GPS is not applicable to indoor positioning and RFID tags cannot provide a fully automated system for position location, the characteristics of UWB systems make this technology a strong candidate for a fully automated positioning system in an indoor construction environment. This thesis presents a comprehensive study of the performance of UWB systems in a controlled laboratory environment and in an institutional construction site in Waterloo, Canada as well as for a particular safety application. A primary objective of the research was to establish the accuracy of real-time position location under various conditions, including the effect of different construction materials (e.g., wood and metal), and to analyze changes in the accuracy of position location as construction progresses and the indoor environment physically evolves. Different challenges faced in implementing such a system in an active construction environment are addressed. Based on a statistical analysis of laboratory data, and considering the construction site experience, the reliability of the UWB positioning system for the aforementioned environments is discussed. Furthermore, an automated safety system is proposed using the real-time UWB positioning technology. Based on the error modeling of the UWB position location, an optimum alarming algorithm is designed for the proposed safety system and the reliability of such system is evaluated through a statistical analysis.

Thesis (M.S.)-- Air Force Institute of Technology. / The original document contains color images.