Global Positioning Systems (GPS) is undergoing stunning changes and upgrades which will enhance the Civil and Military users. This modernization included new satellite signals for Civil and Military purposes which benefits the fundamental signal acquisition and tracking of the GPS receiver. These new signals enable a new family of alternatives for mitigating the ionospheric errors that currently limit the GPS accuracy [16]. A new Civil signal L2 Civil (L2C) was commissioned on the L2 frequency which could have ionospheric error elimination capability, with better cross correlation, Data recovery performance, and threshold tracking. The complex structure of the signal calls for new Acquisition approaches which are implementable with limited computational burden. This thesis proposes an Acquisition methodology to acquire the Code phase offset and Carrier frequency offset of the L2C signal which can be implemented in real time. The algorithm employs a serial code search for Code Phase by retaining the original sampling frequency `fs' and implements a FFT search for carrier frequency offset with a reduced sampling frequency of `fs/M' where `M' is the decimation rate. Multirate Filters are employed for reducing the sampling frequency. After the Acquisition is performed, the values are passed onto the Phase Lock Loop (PLL) and Delay Lock Loop (DLL) to further synchronize the Code Phase and Carrier frequency. The algorithm was tested on a real data set for the performance evaluation of Acquisition and Tracking, and the navigation bits were extracted and the results discussed.

The aim of my thesis was describe a clear form to present the possibilities of facilities for the collection of GIS data for the possible use in land consolidation. My purpose was to accurately determine what the potential cost of purchase and processing of data and how accurately we are able to process this data. Next I have dealt with quality data that we can get from organizations that work with data. I also dealt with the design of land consolidation method using a digital terrain model (DTM). This method could bring a lot of innovation in solving problems in land consolidation in the future

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Made available in DSpace on 2015-06-17T19:33:49Z (GMT). No. of bitstreams: 0 Previous issue date: 2015-02-27. Added 1 bitstream(s) on 2015-06-18T12:47:59Z : No. of bitstreams: 1 000831731.pdf: 4516645 bytes, checksum: 7330beabb262f3e5d147ce9d6cfbc399 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / No monitoramento de deformações de grandes estruturas ou da superfície terrestre, o deslocamento dos pontos investigados geralmente são obtidos em função de pontos localizados fora do corpo de estudo e são considerados como estáveis (pontos de refer ência) nas análises. Se estes pontos, assumidos como referências, na realidade não forem estáveis, os parâmetros nais serão in uenciados diretamente por esta considera ção. Para estabelecer uma rede de referência pontos estáveis devem ser encontrados, ou seja, aqueles que menos se movimentam ao passar do tempo. A instabilidade, ou deslocamento, na posição de um ponto com relação ao tempo pode ser separados em dois tipos: continentais e locais. Os deslocamentos continentais tratam do movimento sofrido pela estação em função da sua velocidade continental, ou seja, devido ao movimento da placa em que se encontra. Já, os deslocamentos locais são obtidos em função de fenômenos físicos da geologia local, podendo ou não ter um padrão de variação. Os deslocamentos locais são os únicos de extremo interesse na de nição de pontos estáveis. Assim, este trabalho propõe uma estratégia para classi cação de pontos estáveis atrav és da obtenção destes deslocamentos sem a in uência dos deslocamentos continentais na posição da estação... / Deformation monitoring of large structures or land surface, the displacement of the investigated points are usually obtained according to points located outside of the studied body and they are considered to be stable (reference points) in the analysis. If these constrained points, assumed as references, in reality are not stable the nal parameters will be directly in uenced by this consideration. To establish a reference network stable points must be found, i.e, those that least move over time. The instability or displacements in the point position with respect to time can be separated into two types: continental and local. The continental displacements treat the su ered motion by the station on the basis of the continental speed, that is, due to the plate movement that the point is locate. The local displacements are obtained as function of physical phenomena of the local geology, they may or may not have a pattern of variation. Local movements are the only of extreme interest in the de nition of stable points. Thus, this work proposes a strategy for classi cation of stable points by using these obtained displacements without the in uence of continental displacements in the station position. Based on coordinate time series obtained from the PPP (Precise Point Positioning) processing method with the GAPS (GPS Analysis and Positioning Software) software, comparing them to coordinates obtained from a velocity model, e.g., the VEMOS2009 (Velocity Model for South America and the Caribbean), is intended to de ne a metric for classi cation of stable points, where the Network Robustness Analysis is adopted as a statistical criterion for evaluation of the proposed mathematical model...

The orbit of a satellite around the earth is constantly disturbed by various factors, such as variations in the gravitational field and the solar wind pressure. The drift of the satellite position can compromise the mission, and even lead to a crash or a fall in the atmosphere. The station-keeping operations therefore consist in performing an accurate measurement of the satellite trajectory and then in using its thrusters to correct the drift. The conventional solution is to measure the position with the help of a ground based radar. This solution is expensive and does not allow to have the satellite position permanently: the trajectory corrections are therefore infrequent. A positioning and autonomous navigation system using constellations of navigation satellites, called Global Navigation Satellite System (GNSS), allows a significant reduction in design and operational maintenance costs. Several studies have been conducted in this direction and the first navigation systems based on GPS receivers, are emerging. A receiver capable of processing multiple navigation systems, such as GPS and Galileo, would provide a better service availability. Indeed, Galileo is designed to be compatible with GPS, both in terms of signals and navigation data. Continuous knowledge of the position would then allow a closed loop control of the station keeping. Initially, we defined what the specifications of a multi-mission space receiver are. Indeed, the constraints on such a receiver are different from those for a receiver located on the surface of the Earth. The analysis of these constraints, and the performance required of a positioning system, is necessary to determine the specifications of the future receiver. There are few studies on the subject. Some of them are classified; others have, in our view, an analytical bias that distorts the determination of specifications. So we modeled the system: GNSS and receivers satellite orbits, radio frequency link. Some parameters of this link are not given in the specification or manufacturers documents. Moreover, the available theoretical data are not always relevant for realistic modeling. So we had to assess those parameters using the available data. The model was then used to simulate various scenarios representing future missions. After defining analysis criteria, specifications were determined from the simulation results. Calculating a position of a satellite navigation system involves three main phases. For each phase, there are several possible algorithms, with different performance characteristics, the circuit size or the computation load. The development of new applications based on navigation also drives the development of new adapted algorithms. We present the principle for determining a position, as well as GPS and Galileo navigation signals. From the signal structure, we explain the phases of the demodulation and localization. Through the use of GPS and Galileo constellations, standard algorithms achieve the performance required for space applications. However, these algorithms need to be adapted, thus some parts were specifically designed. In order to validate the choice of algorithms and parameters, we have simulated the various operating phases of the receiver using real GPS signals. Finally, impact and prospects are discussed in the conclusion.

Made available in DSpace on 2014-06-11T19:22:26Z (GMT). No. of bitstreams: 0 Previous issue date: 2002Bitstream added on 2014-06-13T18:08:17Z : No. of bitstreams: 1 machado_wc_me_prud.pdf: 505198 bytes, checksum: 727c2473f345d9bddfe66e5ea76fa543 (MD5) / O posicionamento com GPS no nível de precisão centimétrico é baseado na medida da fase de batimento da onda portadora. No entanto, esta observável é ambígua de um número inteiro de ciclos entre as antenas do satélite e do receptor no instante da primeira observação, denominado de ambigüidade GPS. Tais ambigüidades são introduzidas como parâmetros nas equações de observação e, devido à sua natureza inteira, não existe um método padrão para solucioná-las diretamente. Uma estratégia comumente utilizada é aplicar o método dos mínimos quadrados seqüencial condicionado juntamente com técnicas de busca. A resolução das ambigüidades pode ser dividida em duas etapas: a estimação e a validação. A estimação diz respeito ao cálculo do valor da ambigüidade. A validação é utilizada para inferir se a solução pode ser aceita ou não. Desde o final da década de 1980, até os dias de hoje, a solução da ambigüidade vem sendo um dos principais tópicos de pesquisa em posicionamento geodésico e vários métodos foram propostos. Atenção especial vem sendo dada à solução rápida das ambigüidades. Essa dissertação apresenta uma nova contribuição no desenvolvimento do software GPSeq, o qual é um software de processamento de dados GPS desenvolvido em meio acadêmico. Inicialmente, o software comportava apenas o processamento de dados coletados através de posicionamento relativo estático de linhas de base curtas. Durante o desenvolvimento de um projeto de iniciação científica (IC) financiado pela Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), o método LAMBDA... / Centimeter level GPS positioning is based on the very precise carrier beat phase measurements. However, this observable is ambiguous by a number of whole cycles between the satellite and receiver antenna at the first epoch of data collecting, which is called the ambiguity. GPS ambiguities are introduced as parameters to be estimated in the observation equations. However, since they are integer numbers there is no standard techniques for solve them. One of the ways is to apply sequential conditional least-squares estimation together with integer search techniques. The ambiguity resolution can be divided in two steps: estimation and validation. The estimation is concerned with the computation of the ambiguities values. The validation step is used to infer if the estimated value can be accepted or not. From the last decade until nowadays ambiguity resolution has been one of the most important research topic in geodetic positioning and a several methods have been proposed. Special attention has been made about the fast ambiguity resolution. This project presents a new contribution to the GPSeq software implementation, which is a GPS data processing software developed in academic environment. Initially, the software was able to process data from static relative positioning for short baselines. During the development of a Scientific Initiation project supported by FAPESP (Fundação de Amparo a Pesquisa do Estado de São Paulo), the LAMBDA method for rapid ambiguity resolution was implemented. In this contribution, local Detection Identification Adaptation (DIA) for float quality control and an algorithm for processing both, kinematic and static relative data, was implemented. An initial study about fixed ambiguity validation was also carried out. Some experiments are presented, whose results shown that the GPSeq solution is compatible on the centimeter level with commercial software... (Complete abstract click electronic address below)

Orientador: João Carlos Chaves / Coorientador: Marcelo Carvalho dos Santos / Banca: Edvaldo Simões da Fonseca Júnior / Banca: Daniele Barroco Marra Alves / Resumo: No monitoramento de deformações de grandes estruturas ou da superfície terrestre, o deslocamento dos pontos investigados geralmente são obtidos em função de pontos localizados fora do corpo de estudo e são considerados como estáveis (pontos de refer ência) nas análises. Se estes pontos, assumidos como referências, na realidade não forem estáveis, os parâmetros nais serão in uenciados diretamente por esta considera ção. Para estabelecer uma rede de referência pontos estáveis devem ser encontrados, ou seja, aqueles que menos se movimentam ao passar do tempo. A instabilidade, ou deslocamento, na posição de um ponto com relação ao tempo pode ser separados em dois tipos: continentais e locais. Os deslocamentos continentais tratam do movimento sofrido pela estação em função da sua velocidade continental, ou seja, devido ao movimento da placa em que se encontra. Já, os deslocamentos locais são obtidos em função de fenômenos físicos da geologia local, podendo ou não ter um padrão de variação. Os deslocamentos locais são os únicos de extremo interesse na de nição de pontos estáveis. Assim, este trabalho propõe uma estratégia para classi cação de pontos estáveis atrav és da obtenção destes deslocamentos sem a in uência dos deslocamentos continentais na posição da estação... / Abstract: Deformation monitoring of large structures or land surface, the displacement of the investigated points are usually obtained according to points located outside of the studied body and they are considered to be stable (reference points) in the analysis. If these constrained points, assumed as references, in reality are not stable the nal parameters will be directly in uenced by this consideration. To establish a reference network stable points must be found, i.e, those that least move over time. The instability or displacements in the point position with respect to time can be separated into two types: continental and local. The continental displacements treat the su ered motion by the station on the basis of the continental speed, that is, due to the plate movement that the point is locate. The local displacements are obtained as function of physical phenomena of the local geology, they may or may not have a pattern of variation. Local movements are the only of extreme interest in the de nition of stable points. Thus, this work proposes a strategy for classi cation of stable points by using these obtained displacements without the in uence of continental displacements in the station position. Based on coordinate time series obtained from the PPP (Precise Point Positioning) processing method with the GAPS (GPS Analysis and Positioning Software) software, comparing them to coordinates obtained from a velocity model, e.g., the VEMOS2009 (Velocity Model for South America and the Caribbean), is intended to de ne a metric for classi cation of stable points, where the Network Robustness Analysis is adopted as a statistical criterion for evaluation of the proposed mathematical model... / Mestre

Thesis submitted in partial fulfilment of the requirements for the degree Master of Technology: Electrical Engineering in the Faculty of Engineering at the Cape Peninsula University of Technology 2015 / Space-borne GPS receivers designed for nano-satellites are faced with various challenges. This research is undertaken to address the problems of inefficiency and high-costs associated with space-borne GPS receivers. The problem of inefficiency relates to poor performances of the GPS receiver in terms of the algorithmic models, execution speed, memory usage and errors proness. The problem of high-costs relates to the spacegrade hardware cost, implementation complexity, development time, as well as the manufacturing, production and the testing processes involved. The research objectives are to i) establish an efficient high-dynamics software-defined GPS receiver, ii) demonstrate a firmware approach and then iii) postulate a low-cost hardware implementation roadmap. The research methodology employed to address the problems and to attain the objectives is based-on using Matlab computing platform to i) implement a software-defined GPS receiver using free open-source GPS receiver algorithms, ii) further develop the software GPS receiver and lastly iii) convert the improved GPS receiver algorithms to firmware. The GPS receiver was successfully implemented in Matlab floating-point algorithms with a ±100kHz Doppler search bins and was used to post-process a pre-captured real GPS L1 C/A signal dataset. The pre-captured GPS signal was acquired, tracked, decoded and post-processed to extract the navigation message; use to compute the GPS receiver position, UTC date and time. Attempt to convert the entire Matlab floating-point GPS receiver algorithms to equivalent VHDL implementations failed; however, three of the Matlab floating-point algorithms (check_t.m, deg2dms.m and findUtmZone.m), were successfully converted to equivalent fixed-point formats in Matlab, Simulink and finally VHDL. These three algorithms, now created and optimised to fixed-point formats (efficient and enable implementation unto a low-cost microcontroller), set the basis for the firmware implementation. They were simulated and verified in Matlab, Simulink and VHDL using the Matlab HDL Coder workflow. Altera Quartus II software was then used to compile (synthesise, place & route and generate programming files) the three converted generic VHDL algorithms to embedded firmware, suitable for a FPGA programming. The Matlab HDL Coder workflow used in this research is feasible and can be used to accurately design and implement an improved GPS receiver and furthermore achieve it in three equivalent algorithms. This conclusion was drawn and the proposed recommendations are to address the conversion issues in the other Matlab floating-point GPS receiver algorithms that failed in the conversion process and to further develop and implement the GPS receiver as a fully functional unit, based-on the Xilinx space-grade, radiation hardened and low-cost Virtex 5QV FPGA.

La réduction de la taille des transistors et des tensions d’alimentations permettent de concevoir des circuits intégrés de plus en plus complexes. Cependant, en abordant les limites de l’intégration des transistors et en fleuretant avec les tensions d’alimentation minimale, la fiabilité des circuits n’est plus garantie : des erreurs dues aux perturbations environnementales peuvent apparaitre. L’apparition de ces erreurs affectent le comportement du circuit et peuvent, par intermittence ou de façon permanente, le rendre inapte à rendre le service pour lequel il a été conçu. Par conséquent, il est de plus en plus important de considérer les effets de ces erreurs dans la conception des futurs circuits. L’objectif de la thèse est de traiter la fiabilité des systèmes numériques et d’introduire de nouvelles techniques de tolérance aux pannes permettant de construire des applications de traitement de signal fiables sur un électronique peu fiable. Un exemple d’application a été considéré durant la thèse : les modules de poursuite dans un récepteur GPS. Ces modules contiennent un ensemble d’applications de traitement de signal avec des exigences de fiabilité différentes : fonction de corrélation, boucles de rétroactions, machines d’états, générateurs de codes et de porteuses. À partir d’une version standard d’un récepteur GPS, des mécanismes de redondance ont été proposés et ajoutés pour concevoir un récepteur GPS plus tolérant aux erreurs. Un circuit intégré (ASIC) sera conçu en utilisant une technologie 28 nm pour valider les performances de ces techniques et faire les tests de mesures de consommation d’énergie. Au cours de la thèse, une plate-forme d’émulation a été conçue pour préparer l’environnement expérimental à utiliser une fois l’ASIC fondu. / There is continual motivation to scale down transistors size and to reduce the supply voltage of the circuits. However, by approaching the limits of transistor scaling and operating at a minimal supply voltage, circuit reliability has emerged as a critical concern. Circuits become more and more susceptible to errors due to Process, Voltage and Temperature (PVT) variations. Occurrence of errors can affect the behavior of circuits and generate a permanent system failure. Therefore, it is increasingly important to deal with errors effects in order to keep future devices working properly. The objective of the thesis is to address the reliability in digital systems and introduce new fault tolerant techniques to perform reliable signal processing applications on unreliable hardware. An example of application has been considered in the thesis: the tracking process of GPS receivers. It contains a very interesting set of different signal processing problem with different requirements of reliability: Correlation process, tracking loops (recursive operations), state machine, Gold and carrier generators. Starting from a noiseless GPS receiver, redundant mechanisms have been proposed and added to design a more resilient GPS receiver tolerant to errors. An Application-Specific Integrated Circuit (ASIC) will be designed, based on thesis results, using the 28 nm technology to validate the performances of the proposed techniques performances. During the thesis, an emulation platform was designed to prepare the experimental environment for the ASIC.

Orientador: João Francisco Galera Monico / Resumo: O posicionamento com GPS no nível de precisão centimétrico é baseado na medida da fase de batimento da onda portadora. No entanto, esta observável é ambígua de um número inteiro de ciclos entre as antenas do satélite e do receptor no instante da primeira observação, denominado de ambigüidade GPS. Tais ambigüidades são introduzidas como parâmetros nas equações de observação e, devido à sua natureza inteira, não existe um método padrão para solucioná-las diretamente. Uma estratégia comumente utilizada é aplicar o método dos mínimos quadrados seqüencial condicionado juntamente com técnicas de busca. A resolução das ambigüidades pode ser dividida em duas etapas: a estimação e a validação. A estimação diz respeito ao cálculo do valor da ambigüidade. A validação é utilizada para inferir se a solução pode ser aceita ou não. Desde o final da década de 1980, até os dias de hoje, a solução da ambigüidade vem sendo um dos principais tópicos de pesquisa em posicionamento geodésico e vários métodos foram propostos. Atenção especial vem sendo dada à solução rápida das ambigüidades. Essa dissertação apresenta uma nova contribuição no desenvolvimento do software GPSeq, o qual é um software de processamento de dados GPS desenvolvido em meio acadêmico. Inicialmente, o software comportava apenas o processamento de dados coletados através de posicionamento relativo estático de linhas de base curtas. Durante o desenvolvimento de um projeto de iniciação científica (IC) financiado pela Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), o método LAMBDA... (Resumo completo clicar acesso eletrônico abaixo) / Abstract: Centimeter level GPS positioning is based on the very precise carrier beat phase measurements. However, this observable is ambiguous by a number of whole cycles between the satellite and receiver antenna at the first epoch of data collecting, which is called the ambiguity. GPS ambiguities are introduced as parameters to be estimated in the observation equations. However, since they are integer numbers there is no standard techniques for solve them. One of the ways is to apply sequential conditional least-squares estimation together with integer search techniques. The ambiguity resolution can be divided in two steps: estimation and validation. The estimation is concerned with the computation of the ambiguities values. The validation step is used to infer if the estimated value can be accepted or not. From the last decade until nowadays ambiguity resolution has been one of the most important research topic in geodetic positioning and a several methods have been proposed. Special attention has been made about the fast ambiguity resolution. This project presents a new contribution to the GPSeq software implementation, which is a GPS data processing software developed in academic environment. Initially, the software was able to process data from static relative positioning for short baselines. During the development of a Scientific Initiation project supported by FAPESP (Fundação de Amparo a Pesquisa do Estado de São Paulo), the LAMBDA method for rapid ambiguity resolution was implemented. In this contribution, local Detection Identification Adaptation (DIA) for float quality control and an algorithm for processing both, kinematic and static relative data, was implemented. An initial study about fixed ambiguity validation was also carried out. Some experiments are presented, whose results shown that the GPSeq solution is compatible on the centimeter level with commercial software... (Complete abstract click electronic address below) / Mestre