The Global Navigation System Scope (GNSScope): a toolbox for the end-to-end modelling simulation and analysis of GNSS

The thesis provides a detailed overview of the work carried out by the author over the course of the research for the award of the degree of Doctor of Philosophy at the University of Westminster, and the performance results of the novel techniques introduced into the literature. The outcome of the work is collectively referred to as the Global Navigation System Scope (GNSScope) Toolbox, offering a complete, fully reconfigurable platform for the end-to-end modeling, simulation and analysis of satellite navigation signals and systems, covering the signal acquisition, tracking, and range processing operations that take place in a generic Global Navigation Satellite System (GNSS) receiver, accompanied by a Graphical User Interface (GUI) providing access to all the techniques available in the toolbox. Designed and implemented entirely in the MATLAB mathematical programming environment using Software Defined Radio (SDR) receiver techniques, the toolbox offers a novel new acquisition algorithm capable of handling all Phase-Shift Keying (PSK) type modulations used on all frequency bands in currently available satellite navigation signals, including all sub-classes of the Binary Offset Carrier (BOC) modulated signals. In order to be able to process all these signals identified by the acquisition search, a novel tracking algorithm was also designed and implemented into the toolbox to track and decode all acquired satellite signals, including those currently intended to be used in future navigation systems, such as the Galileo test signals transmitted by the GIOVE satellites orbiting the Earth. In addition to the developed receiver toolbox, three novel algorithms were also designed to handle weak signals, multipath, and multiple access interference in GNSScope. The Mirrored Channel Mitigation Technique, based on the successive and parallel interference cancellation techniques, reduces the hardware complexity of the interference mitigation process by utilizing the local code and carrier replicas generated in the tracking channels, resulting in a reduction in hardware resources proportional to the number of received strong signals. The Trigonometric Interference Cancellation Technique, used in cross-correlation interference mitigation, exploits the underlying mathematical expressions to simplify the interference removal process, resulting in reduced complexity and execution times by reducing the number of operations by 25% per tracking channel. The Split Chip Summation Technique, based on the binary valued signal modulation compression technique, enhances the amount of information captured from compressing the signal to reveal specific filtering effects on the positive and negative polarity chips of the spreading code. Simulation case studies generated entirely using the GNSScope toolbox will be used throughout the thesis to demonstrate the effectiveness of the novel techniques developed over the course of the research, and the results will be compared to those obtained from other techniques reported in the literature

Methods for Improving Performance in Consumer Grade GNSS Receivers

Viimeisten kolmen vuosikymmenen aikana satelliittinavigointi on kehittynyt ammatti ja sotilaskäyttäjien tekniikasta kaikkien saatavilla olevaksi tekniikaksi. Varsinkin viimeisen 15 vuoden aikana, kun vastaanottimet alkoivat pienentyä ja halpenivat, on lisääntynyt määrä yrityksiä, jotka toimittavat GPS-laitteita satoihin erilaisiin sovelluksiin. Kaikille moderneille tekniikoille on myös tyypillistä, että tutkimukseen ja siihen liittyvään vastaanottimien kehittämiseen on käytetty valtavasti rahaa, mikä on johtanut huomattavaan parantumiseen vastaanottimen suorituskyvyssä. GPS-vastaanottimien kehitystyön lisäksi uusien maailmanlaajuisten satelliittinavigointijärjestelmien, kuten venäläisen GLONASS, kiinalaisen BeiDou- ja eurooppalaisen Galileo-järjestelmien käyttöönotto tarjoaa entistä enemmän mahdollisuuksia suorituskyvyn parantamiseen. Sekä GPS että nämä uudet järjestelmät ovat myös ottaneet käyttöön uudentyyppisiä signaalirakenteita, jotka voivat tarjota parempilaatuisia havaintoja ja siten parantaa kaikkien vastaanottimien suorituskykyä. Lopuksi menetelmät, kuten PPP ja RTK, jotka aiemmin olivat varattu ammattikäyttäjille, ovat tulleet kuluttajamarkkinoille mahdollistaen ennennäkemättömän suorituskyvyn jokaiselle satelliittinavigointivastaanottimien käyttäjälle. Tässä opinnäytetyössä arvioidaan tämän kehityksen vaikutusta sekä suorituskykyyn että vastaanottimen arkkitehtuuriin. Työssä esitellään yksityiskohtaisesti FGI:ssä kehitetyn ohjelmistopohjaisen vastaanottimen, FGI-GSRx:n. Tämän vastaanottimen avulla on työssä arvioitu miten sekä uudet konstellaatiot että uudet nykyaikaiset signaalit ja niitten seurantamenetelmät vaikuttavat suorituskykyyn ja vastaanotin arkkitehtuuriin. Tämän lisäksi on arvioitu PPP- ja RTK-tarkkuuspaikannusmenetelmien vaikutus FinnRefCORS-verkkoa käyttäen useiden erityyppisten vastaanottimien kanssa, mukaan lukien kuluttajalaatuiset vastaanottimet. Tulokset osoittavat, että enemmän konstellaatioita ja signaaleja käytettäessä paikannusratkaisun tarkkuus paranee 3 metristä 1,4 metriin hyvissä olosuhteissa ja yli 10-kertaiseksi tiheästi rakennetuissa kaupungeissa, jossa käytettävissä olevien signaalien määrä kasvaa kertoimella 2 käytettäessä kolmea konstellaatiota. Uusia moderneja modulaatiotekniikoita, kuten BOC-modulaatiota, käytettäessä tulokset osoittavat Galileo-ratkaisun tarkkuuden paranevan lähes 25%:lla ja esitelty uusi signaalinkäsittelymenetelmä lisää tällaisen tarkkuuden saatavuutta 50%:sta lähes 100%:iin. Lopuksi tarkkuuspaikannusmenetelmien tulokset osoittavat, että 15 cm:n tarkkuus on saavutettavissa, mikä on merkittävä parannus verrattuna 1,4 metrin tarkkuuteen. Näiden parannusten saavuttamiseksi on olennaista, että itse vastaanotin on mukautettu hyödyntämään näitä uusia signaaleja ja konstellaatioita. Tämä tarkoittaa, että nykyaikaisten kuluttajamarkkinoiden vastaanottimien suunnittelu on haastavaa ja monissa tapauksissa ohjelmistopohjainen vastaanotin olisi parempi ja halvempi valinta kuin uusien mikropiirien kehittäminen.For the last three decades, satellite navigation has evolved from being a technology for professional and military users to a technology available for everyone. Especially during the last 15 years, since the receivers started getting smaller and cheaper, there has been an increasing number of companies delivering Global Positioning System (GPS) enabled devices for hundreds of different kind of applications. Typical for any modern technology, there has also been an enormous amount of money spent on research and accompanied receiver development resulting in an immense increase in receiver performance. In addition to the development efforts on GPS receivers the introduction of new global navigation satellite systems such as the Russian Globalnaja Navigatsionnaja Sputnikovaja Sistema (GLONASS), the Chinese BeiDou, and the European Galileo systems offers even more opportunities for improved performance. Both GPS and these new systems have also introduced new types of signal structures that can provide better quality observations and even further improve the performance of all receivers. Finally, methods like Precise Point Positioning (PPP) and Real Time Kinematic (RTK) that earlier were reserved for professional users have entered into the consumer market enabling never before seen performance for every user of satellite navigation receivers. This thesis will assess the impact of this development on both performance as well as on receiver architecture. The design of the software defined receiver developed at FGI, the FGI-GSRx, is presented in detail in this thesis. This receiver has then been used to assess the impact of using multiple constellations as well as new novel signal processing methods for modern signals. To evaluate the impact of PPP and RTK methods the FinnRef Continuously Operating Reference Station (CORS) network has been used together with several different types of receivers including consumer grade off the shelf receivers. The results show that when using more constellations and signals the accuracy of the positioning solution improves from3 meters to 1.4 meters in open sky conditions and by more than a factor 10 in severe urban canyons. For severe urban canyons the available also increases by a factor 2 when using three constellations. When using new modern modulation techniques like high order BOC results show an accuracy improvement for a Galileo solution of almost 25 % and the presented new signal processing method increase the availability of such an accuracy from 50 % to almost 100 %. Finally, results from precise point positioning methods show that an accuracy of 15 cm is achievable, which is a significant improvement compared to an accuracy of 1.4 m for a standalone multi constellation solution. To achieve these improvements, it is essential that the receiver itself is adapted to make use of these new signals and constellations. This means that the design of modern consumer market receivers is challenging and in many cases a software define receiver would be a better and cheaper choice than developing new Application Specific Integrated Circuit (ASIC)’s

New methods and architectures for high sensitivity hybrid GNSS receivers in challenging environments

GNSS satellite navigation systems are constantly evolving and have been already used in many applications. With the advent of the new systems Galileo and BeiDou as well as the modernization of GPS and GLONASS systems, new satellites and numerous new frequencies and signals will appear in the coming years and will open door to countless new applications that are currently impossible. The rapid evolution of mobile telephony and personal navigation devices (PND) requires better use of navigation systems in non-ideal environments, especially the need for positioning in deep urban area. On the one hand, users are waiting for a high positioning accuracy, because of the proximity to various points of interest. On the other hand, urban environment brings specific difficulties in receiving GNSS signals. GNSS navigation signals cannot be properly captured in urban and "indoor" environments. Signal levels are very low and it is almost impossible to acquire and track signals autonomously because of the strong attenuation of signals due to obstacles. In addition, indoor and urban positioning are also subject to multipath problems, masking, interference and jamming. Under these conditions, we must be able to process highly degraded or very short signals that do not allow the receiver to go through the tracking process. Thus, this leads us to the need to rethink the architecture of GNSS receiver for modern applications. This thesis project consists of developing new GNSS methods and architectures of high sensitivity and robustness to signal degradations and designing new algorithms integrated into a hybrid GNSS receiver capable of operating in deep urban environments. The methodology involves the use of the new concept of “Collective Detection (CD)”, also called “collaborative acquisition”. The collaborative approach that treats multi-satellite signals all together opens an interesting solution. Many techniques exist in the literature to solve the problems of positioning in urban environments, but we propose the new Collective Detection approach because of its performance as both a Direct Positioning (DP) method, providing a coarse position/clock-bias solution directly from acquisition, and High-Sensitivity (HS) acquisition method, by application of vector detection of all satellites in view. Indeed, the correct combination of the correlation values of several satellites can reduce the required Carrier-to-Noise Ratio (C/No) level of the satellite signals which cannot be acquired individually by standard signal processing (acquisition and tracking) but make it possible to use them constructively to a positioning solution. The combination of different GNSS signals can considerably increase the acquisition sensitivity of the receiver. Despite the advantages of this approach, it also has drawbacks such as the high computational burden because of the large number of candidate points in the position/clock-bias domain. Thus, the work proposed in this thesis consists of reducing the complexity of the CD by optimizing the search for candidate points in position/clock-bias domain. Finally, the goal is to apply the CD approach to Cooperative GNSS Positioning for modern navigation in harsh environments. For that, algorithms for optimally exploiting receiver resources by selecting the best satellites or the reference station will be developed according to certain criteria such as the C/No level, the elevation angle, and the geometric configuration of the visible satellites. The ultimate goal is to propose a design of a new smart receiver “High Sensitivity Cognitive GNSS Receiver (HSCGR)” to optimally receive and process GNSS signals

GNSS-Based Navigation for Lunar Missions

Numerous applications, not only Earth-based, but also space-based, have strengthened the interest of the international scientific community in using Global Navigation Satellite Systems (GNSSs) as navigation systems for space missions that require good accuracy and low operating costs. Indeed, already used in Low Earth Orbits (LEOs), GNSS based-navigation GNSS-based navigation systems can maximize the autonomy of a spacecraft while reducing the costs of ground operations, allowing for budget-limited missions of micro- and nanosatellites. This is why GNSS is also very attractive for applications in higher Earth orbits up to the Moon, such as in Moon Transfer Orbits (MTOs). However, while GNSS receivers have already been exploited with success for LEOs, their use in higher Earth orbits above the GNSS constellation is extremely challenging, particularly on the way from the Earth to the Moon, characterized by weaker signals with wider gain variability, larger dynamic ranges resulting in higher Doppler and Doppler rates, critically lower satellite signal availability, and poorer satellite-to-user geometry. In this context, the first research objective and achievement of this PhD research is a feasibility study of GNSS as an autonomous navigation system to reach the Moon, and the determination of the requirements for the design of a code-based GNSS receiver for such a mission. The most efficient combinations of signals transmitted by the GPS, Galileo, and combined GPS-Galileo constellations have been identified by analyzing the theoretical achievable signal acquisition and tracking sensitivities, the resultant constellation availability, the pseudorange error factors, and the geometry error factor and accordingly the achievable navigation performance The results show that GNSS signals can be tracked up to Moon altitude, but not with the current GNSS receiver technology for terrestrial use. The second research objective and achievement is the design and implementation of a GNSS receiver proof-of-concept capable of providing GNSS observations onboard a space vehicle orbiting up to Moon altitude. This research work describes the hardware architecture, the high-sensitivity acquisition and tracking modules and the standalone single-epoch navigation performance of the developed GPS L1 C/A hard-ware receiver, named the WeakHEO receiver. Although they can still be collected, GNSS observations at Moon altitude, if not filtered, but simply used to compute a single-epoch least-squares solution, lead to a very coarse navigation accuracy, on the order of 1 to 10 km, depending on the number and type of signals successfully processed. Therefore, the third and main research objective and achievement is the design and implementation of a GNSS-based orbital filter (OF) determination unit, based on an extended Kalman filter (EKF) and an orbital forces model, able to significantly improve the achievable navigation performance and also to aid acquisition and tracking modules of the GNSS receiver. Simulation results of the OF performance when processing simulated GPS and Galileo observations, but also real GPS L1 C/A observations provided by the WeakHEO receiver (when connected in a hardware in the loop configuration to a full constellation GNSS radio frequency signal simulator), show a positioning accuracy at Moon altitude of a few hundred meters

Physical Layer Challenges and Solutions in Seamless Positioning via GNSS, Cellular and WLAN Systems

As different positioning applications have started to be a common part of our lives, positioning methods have to cope with increasing demands. Global Navigation Satellite System (GNSS) can offer accurate location estimate outdoors, but achieving seamless large-scale indoor localization remains still a challenging topic. The requirements for simple and cost-effective indoor positioning system have led to the utilization of wireless systems already available, such as cellular networks and Wireless Local Area Network (WLAN). One common approach with the advantage of a large-scale standard-independent implementation is based on the Received Signal Strength (RSS) measurements.This thesis addresses both GNSS and non-GNSS positioning algorithms and aims to offer a compact overview of the wireless localization issues, concentrating on some of the major challenges and solutions in GNSS and RSS-based positioning. The GNSS-related challenges addressed here refer to the channel modelling part for indoor GNSS and to the acquisition part in High Sensitivity (HS)-GNSS. The RSSrelated challenges addressed here refer to the data collection and calibration, channel effects such as path loss and shadowing, and three-dimensional indoor positioning estimation.This thesis presents a measurement-based analysis of indoor channel models for GNSS signals and of path loss and shadowing models for WLAN and cellular signals. Novel low-complexity acquisition algorithms are developed for HS-GNSS. In addition, a solution to transmitter topology evaluation and database reduction solutions for large-scale mobile-centric RSS-based positioning are proposed. This thesis also studies the effect of RSS offsets in the calibration phase and various floor estimators, and offers an extensive comparison of different RSS-based positioning algorithms

Design and development of a technological demonstrator for the study of high dynamics GNSS receivers

[ES] En el marco de esta tesis se van a estudiar, principalmente, los efectos del movimiento de alta dinámica en receptores de Sistemas Globales de Navegación por Satélite (GNSS). El término alta dinámica es un término utilizado para referirse al movimiento de los vehículos en los que van embarcados receptores GNSS, los cuales se mueven lo suficientemente rápido como para causar un gran desplazamiento en frecuencia de la portadora debido al efecto Doppler. Se identificarán los problemas inherentes a este tipo de entornos y se estudiarán y propondrán soluciones. Para poder efectuar el estudio de estos fenómenos, se diseñará un demostrador tecnológico (conjunto de hardware y software para prueba y prototipado de tecnologías) en el que desarrollar el estudio de los casos de interés. Con el fin de trabajar en un entorno repetible, se utilizará un generador de señal GNSS. La señal generada se traslada a un receptor de radiofrecuencia definido por software, Software Defined Radio (SDR). Este tipo de receptor únicamente se encarga de digitalizar la señal de entrada y de llevar las muestras digitales a un ordenador, de modo que todo el procesado de señal se implementa en dicho ordenador. Este esquema de trabajo es ideal habida cuenta de su simplicidad y flexibilidad. Dicha flexibilidad conlleva la posibilidad de sintonizar el demostrador para poder estudiar una amplia gama de arquitecturas de receptor GNSS. Una vez se haya ensamblado el demostrador, se comprobará su correcto funcionamiento en escenarios conocidos usando los algoritmos más utilizados a día de hoy en receptores GNSS. Asegurado el correcto funcionamiento, se comparará el rendimiento de algoritmos de referencia con los algoritmos a estudiar y se extraerán conclusiones.[CA] En aquest treball s'estudiaran, principalment, els efectes del moviment d'alta dinámica en receptors de Navegació per Satèl.lit GNSS (Global Navigation Satellite System). La denominació alta dinámica, s'utilitza per a descriure el moviment dels vehicles dins dels quals hi han receptors GNSS. El moviment d'aquests vehicles és suficientment ràpid com per a causar un gran desplaçament en freqüència de la freqüència portadora. Aquest desplaçament és consqüència de l'efecte Doppler. S'identificaran els problemes inherents d'aquest tipus de entorns GNSS i es propsararàn solucions. Per a estudiar l'efecte de l'alta dinàmica, es dissenyarà un demostrador tecnològic (conjunt de maquinari i software per a proves i prototipat de tecnologies) en que es pot desenvolupar l'estudi dels casos d'interès. Amb l'objectiu d'aconseguir treballar en un entorn repetible s'utilitzarà un generador de senyal GNSS. El senyal es processarà mitjançant un receptor SDR (Software Defined Radio). Aquest tipus de receptor s'encarrega del processat que fa un receptor GNSS en un PC. Aquesta filosofia de treball és idónia per la seua flexibilitat i simplicitat. Quan s'haja ensamblat el demostrador, és comprovarà el seu correct funcionament en escenaris de prova utilitzant els algoritmes implementats en receptors GNSS comercials. En aquest moment, el demostrador estarà preparat per a estudiar el casos d'alta dinàmica, que és l'objectiu fonamental d'aquest treball.[EN] The study of the effects of the high dynamics on Global Navigation Satellite System (GNSS) receivers constitute the main matter of study in this work. The term high dynamics refers to the movement of vehicles that carry GNSS embedded receivers, which move fast enough to generate a large carrier frequency drift caused by the Doppler effect. The problems linked to these environments will be characterized and solutions to counteract possible signal impairments will be discussed. In order to correctly characterize these problems, a technological demonstrator (set of hardware components interacting with software tools enabling fast prototyping) will be designed and constructed. Using this technological demonstrator, different case studies will be developed. With the aim of achieving experimental repeatability, a GNSS signal generator will be used. The generated GNSS signal is fed to a Software Defined Radio (SDR) GNSS receiver. This receiver type is in charge of digitizing the analog RF signal and carrying the resulting samples to a computer in which signal processing tasks implementing the functions of GNSS receivers, take place. The main advantage linked to the usage of this work scheme is that by changing the software part, different receiver architectures can be implemented in a simple manner. Furthermore, by taking advantage of the flexible architecture it is possible to tune the detector in such a manner that it is possible to implement many different architecture types. Once the technological demonstrator is assembled, tests to assure its correct operation will be conducted by performing comparisons with the behaviour of well-known GNSS receivers in known scenarios. Later on, comparative tests using signals from high dynamics scenarios will take place. Insight and analysis of comparative performance will be given.Alcaide Guillén, C. (2019). Design and development of a technological demonstrator for the study of high dynamics GNSS receivers [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/131697TESI

Localization Precise in Urban Area

Nowadays, stand-alone Global Navigation Satellite System (GNSS) positioning accuracy is not sufficient for a growing number of land users. Sub-meter or even centimeter accuracy is becoming more and more crucial in many applications. Especially for navigating rovers in the urban environment, final positioning accuracy can be worse as the dramatically lack and contaminations of GNSS measurements. To achieve a more accurate positioning, the GNSS carrier phase measurements appear mandatory. These measurements have a tracking error more precise by a factor of a hundred than the usual code pseudorange measurements. However, they are also less robust and include a so-called integer ambiguity that prevents them to be used directly for positioning. While carrier phase measurements are widely used in applications located in open environments, this thesis focuses on trying to use them in a much more challenging urban environment. To do so, Real Time-Kinematic (RTK) methodology is used, which is taking advantage on the spatially correlated property of most code and carrier phase measurements errors. Besides, the thesis also tries to take advantage of a dual GNSS constellation, GPS and GLONASS, to strengthen the position solution and the reliable use of carrier phase measurements. Finally, to make up the disadvantages of GNSS in urban areas, a low-cost MEMS is also integrated to the final solution. Regarding the use of carrier phase measurements, a modified version of Partial Integer Ambiguity Resolution (Partial-IAR) is proposed to convert as reliably as possible carrier phase measurements into absolute pseudoranges. Moreover, carrier phase Cycle Slip (CS) being quite frequent in urban areas, thus creating discontinuities of the measured carrier phases, a new detection and repair mechanism of CSs is proposed to continuously benefit from the high precision of carrier phases. Finally, tests based on real data collected around Toulouse are used to test the performance of the whole methodology

Position, velocity and time measurement with multiple constellation data from GPS, GALILEO, GLONASS and BEIDOU

Il presente lavoro si propone di illustrare la teoria, il metodo e le modalità del calcolo della PVT, ovvero della posizione, della velocità e del sincronismo temporale, di un utente sulla Terra o di un satellite in orbita bassa (dotato di ricevitore multiGNSS), utilizzando un software integrato che sfrutti tutti i segnali provenienti da tutte le costellazioni a copertura globale in quel momento visibili. Nel caso presente si sono utilizzati i segnali da GPS, Galileo, GLONASS e BeiDou, rilevati grazie ad un ricevitore fornito dall'Università di Padova (STONEX S580), sia per la determinazione della posizione, sia per implementare il calcolo della velocità attraverso l'effetto Doppler. Questo lavoro, in futuro, potrebbe portare a contributi nello sviluppo di tecnologie innovative in molti settori, quali: navigazione autonoma e trasporti, difesa e aerospazio, agricoltura e molti altri.This work intends to outline the theory and the methods for the computation of position, velocity and time (PVT) of a user on the surface of the Earth or of a LEO satellite (Low Earth Orbit). An integrated software written in MATLAB and PERL has been used; it processes all the signals transmitted by all the constellations visible in that precise moment and in that precise place. The software's core uses the Weighted Least Squares algorithm, which permits the efficient computation of position, speed, timing and tropospheric delay in a few iterations. In this thesis, signals from GPS, Galileo, BeiDou and GLONASS have been used, specifically for the computation of the speed, which is calculated from the Doppler Effect. These signals were detected through a receiver STONEX Cube-a S580 provided by the University of Padua. A good precision in determination of both positioning and speed has been achieved and also the PNT of a LEO satellite (Sentinel 3A) has been determined successfully, using data also to study J2 perturbations on the orbit. The principal aim of this thesis is to provide an efficient and precise software able to process pseudorange and Doppler shift multi-constellation data, to enhance, in its future evolutions, the precise positioning of a receiver on Earth's surface and in orbit, with interesting applications in many different fields such as defence, transportations and automotive, attitude determination in space and many others

Performance Analysis of the Modernized GNSS Signal Acquisition

Depuis le développement du GPS, les systèmes de navigation par satellites (GNSS) se sont largement diversifiés : maintenance, modernisation et déploiement de nouveaux systèmes, comme l’européen Galileo. De plus, le nombre d’applications basées sur l’utilisation de signaux GNSS ne cesse d’augmenter. Pour répondre à ces nouveaux challenges et besoins, les récepteurs GNSS ne cessent d’évoluer. Un nouvel axe est le développement du récepteur logiciel qui présente la particularité d’un traitement logiciel des signaux contrairement au récepteur matériel, équipant nos véhicules, smartphones par exemple. Cette thèse de doctorat s’inscrit dans le projet commun d’un laboratoire et d’une PME consistant au développement d’un récepteur logiciel poursuivant les signaux GPS L1 C/A et Galileo E1 OS. L’objectif plus spécifique de la thèse est d’étudier l’acquisition, première étape du traitement du signal GNSS qui doit fournir une estimation grossière des paramètres du signal entrant. Ce travail vise particulièrement les signaux à faible puissance, un seuil d’acquisition est fixé à 27 dB-Hz pouvant s’apparenter à l’acquisition en milieu urbain ou dégradé. Il est important de noter qu’une des contraintes est de réussir l’acquisition de tels signaux au moins 9 fois sur 10, sans aucune aide extérieure ou connaissance des almanachs ou éphémérides. Dans un premier temps, une solide étude théorique portant sur les performances de l’acquisition et les sources de dégradations est menée. Parmi elles, peuvent être citée, les transitions de bits dues à la présence du message de navigation et du code secondaire sur la voie pilote des nouveaux signaux. Est ainsi mis en lumière la nécessité d’avoir recours à une méthode d’acquisition insensible aux inversions de signe du message de navigation. Dans un deuxième temps, une méthode innovante, le Double-Block Zero-Padding Transition-Insensitive (DBZPTI), est donc développée pour permettre l’acquisition du signal Galileo E1 OS de façon efficiente. Elle prend part au développement de la stratégie globale d’acquisition dont l’objectif est d’avoir en sortie une estimation de la fréquence Doppler et du retard de code du signal entrant, assez fine et fiable pour une satisfaisante poursuite du signal. ABSTRACT : Since the development of the GPS, the global navigation satellite systems (GNSS) have been widely diversified: maintenance, modernization and deployment of new systems such as the European Galileo. In addition, the number of GNSS signals applications, based on the use of GNSS signals, is increasing. To meet these new challenges and requirements, GNSS receivers are constantly evolving. A new trend is the development of software receiver which processes the GNSS signal in a software way unlike hardware receiver, equipping our vehicles, smartphones, for example. This thesis is part of a common project between a laboratory and a company, consisting of the development of a software receiver tracking GPS L1 C/A and Galileo E1 OS. The more specific aim of the thesis is to study the acquisition, first signal processing which provides a rough estimation of the incoming signal parameters. This work focuses particularly the low power signals, an acquisition threshold is set at 27 dB-Hz considered as a representative of urban or degraded environments. It is important to note that the success of the acquisition of such signals should be at least 9 times out of 10, without any aid or knowledge of almanac or ephemeris. Initially, a solid theoretical study of the acquisition performance and sources of degradation is conducted. One of them is the bit transitions due to the presence of the navigation message and the secondary code on pilot component of the new signals. It is thus highlighted the need to use a Transition-Insensitive acquisition method. Secondly, an innovative method, the Double-Block Zero-Padding Transition-Insensitive (DBZPTI) is developed to permit efficiently the acquisition of Galileo E1 OS signal. It takes part in the development of the global acquisition strategy, which should provide an estimate of the Doppler frequency and code delay, fine and reliable, for a satisfactory signal tracking

Performance Analysis of the Modernized GNSS Signal Acquisition

Since the development of the GPS, the global navigation satellite systems (GNSS) have been widely diversified: maintenance, modernization and deployment of new systems such as the European Galileo. In addition, the number of GNSS signals applications, based on the use of GNSS signals, is increasing. To meet these new challenges and requirements, GNSS receivers are constantly evolving. A new trend is the development of software receiver which processes the GNSS signal in a software way unlike hardware receiver, equipping our vehicles, smartphones, for example. This thesis is part of a common project between a laboratory and a company, consisting of the development of a software receiver tracking GPS L1 C/A and Galileo E1 OS. The more specific aim of the thesis is to study the acquisition, first signal processing which provides a rough estimation of the incoming signal parameters. This work focuses particularly the low power signals, an acquisition threshold is set at 27 dB-Hz considered as a representative of urban or degraded environments. It is important to note that the success of the acquisition of such signals should be at least 9 times out of 10, without any aid or knowledge of almanac or ephemeris. Initially, a solid theoretical study of the acquisition performance and sources of degradation is conducted. One of them is the bit transitions due to the presence of the navigation message and the secondary code on pilot component of the new signals. It is thus highlighted the need to use a Transition-Insensitive acquisition method. Secondly, an innovative method, the Double-Block Zero-Padding Transition-Insensitive (DBZPTI) is developed to permit efficiently the acquisition of Galileo E1 OS signal. It takes part in the development of the global acquisition strategy, which should provide an estimate of the Doppler frequency and code delay, fine and reliable, for a satisfactory signal tracking