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Aquesta tesi es desenvolupa en el context de la missió Lunar GNSS Receiver Experiment de la NASA i la ASI, que té com a objectiu demostrar el posicionament, la navegació i el temps basats en GNSS a la Lluna mitjançant el desplegament d'un receptor multiconstel·lació del sistema de navegació per satèl·lit amb cobertura global. El projecte es desplega sota la supervisió del grup NavSAS del Politecnico di Torino. La finalitat del projecte és el desenvolupament d'una aplicació que permeti l'anàlisi i simulació de mesures GNSS sense processar. El software ha de ser modular, flexible i fàcil d'utilitzar. Outgoing

The navigation technology has developed rapidly and immensely over the past few decades. Among the multiple navigation technologies, the representative and promising techniques are Real-time Kinematic (RTK) technique and Simultaneous Localization and Mapping (SLAM). RTK can provide real-time positioning results with high accuracy, while SLAM can not only locate the user but also construct a map of the new ambient. The first smartphone, the Xiaomi MI 8, equipped with the dual-frequency Global Navigation Satellite System (GNSS), hit the market in May 2018, providing valid carrier-phase measurements for RTK owe to the developer option of ”Force full GNSS measurements.” Nevertheless, RTK underperforms in urban areas as the buildings and trees can block the satellite signals. RTK cannot even provide positioning results when the GNSS outage happens. However, SLAM can effectively make up the drawbacks of RTK as it utilizes no more information than the images. SLAM can also be combined with the Inertial Measurement Unit (IMU) called Visual-Inertial SLAM (VI-SLAM,) with the improvement of accuracy and robustness. Therefore, our study mainly aims to confirm the feasibility of continuous positioning based on RTK and VI-SLAM with the Xiaomi MI 8. An application is developed to execute the functions, including logging images, measurements of IMU, and GPS measurements in Receiver INdependent EXchange (RINEX) format with the Xiaomi MI 8. The performances of RTK with and without the assistance of VI-SLAM are assessed respectively in the urban area. The experimental results demonstrate that the combination of RTK and VI-SLAM based on smartphones can effectively provide continuous positioning results. We believe our application will facilitate research and development in relation to positioning algorithms. Readers have access to this application at https://github.com/Nronaldo/CIGRLogger.

[EN] Nowadays, as the number of GNSS services are increasing, it is necessary to study and evaluate with real data the enhanced capabilities which these positioning products can provide, and how they are evolving compared with their legacy services and its competitors. Among the emerging positioning services, it is noteworthy Europe's GALILEO system, which is close to reach its full operational capability, and is willing to fulfill competitive user level performances which can be used through its open service signals: E1, E5a and E5b. On the legacy side, the most remarkable constellation is USA's GPS, which has been achieving a positioning standard service with the C/A signal and a precise positioning service for military purposes with the P signal. In addition, GPS evolutions will provide a civilian service through more robust signals, such as the L5. The objective of this work is to compare open positioning services from GPS and GALILEO constellations by analyzing their accuracy and integrity performances obtained from a pre-planned campaign, taking as reference-data the IGS station network. The positioning methodology to be used is post-processing single-frequency pseudorange observations in static mode. For committing this purpose, the main workload is focused on developing a configurable and flexible SW tool which is able to batch the pseudorange observations provided by the spatial frame of the GPS and GALILEO satellites, in order to estimate the receiver's position by means of a Least Squares routine. Lately, these data will be inputted in other analysis tools, which will also be developed in the framework of this project, in order to summarize and display the obtained performances. Consequently, and supported by the obtained results, the conclusions regarding the evolution of the studied services will be drawn., [ES] Actualmente, mientras el número de servicios GNSS disponibles aumenta, resulta necesario evaluar con datos reales las mejoras que ofrecen los nuevos productos de posicionamiento, y cuál es su desempeño y evolución respecto de sus servicios antecesores y el de sus competidores. Entre los servicios de posicionamiento emergentes, resulta de especial interés el proporcionado por la constelación Europea de GALILEO, la cual está cerca de alcanzar su completa capacidad operacional, y que resulta prometedora en cuanto a sus requisitos de prestaciones a nivel usuario, que pueden obtenerse mediante el uso de las señales de su servicio abierto: E1, E5a y E5b. De entre los sistemas ya existentes, el más destacado es el proporcionado por la constelación Estadounidense de GPS, el cual ha estado permitiendo con la señal C/A un servicio de posicionamiento estándar y un servicio de posicionamiento preciso con la seña P para fines militares. Adicionalmente las evoluciones del sistema GPS planean transmitir un servicio civil con señales más robustas, como puede ser la L5. El objetivo de este trabajo es comparar los servicios abiertos de posicionamiento de las constelaciones de GPS y GALILEO, mediante el análisis de sus prestaciones de precisión e integridad obtenidas de una campaña de observación, dónde los datos de referencia a usar son la red de estaciones del IGS. La metodología de posicionamiento a implementar es el post-procesado de observables de pseudo-rango mono-frecuencia en modo estático. Para alcanzar este objetivo, el esfuerzo principal estará enfocado en el desarrollo de una herramienta SW totalmente configurable por el usuario, que sea capaz de procesar los observables de pseudorango proporcionados por el marco de referencia espacial que forman los satélites de GPS y GALILEO, para posteriormente obtener las posiciones del receptor por medio de un algoritmo de estimación por mínimos cuadrados. Los resultados que se obtengan de este procesamiento serán transmitidos a otras herramientas de análisis, las cuales se desarrollarán también en el marco de este proyecto, con la finalidad de resumir y presentar de manera gráfica las prestaciones obtenidas de la campaña. Finalmente, con el soporte de estos resultados, se expondrán las conclusiones sobre el desempeño y la evolución de los servicios anteriormente comentados., [CA] Actualment, mentre el nombre de serveis GNSS disponibles augmenta, cal avaluar amb dades reals les millores que ofereixen els nous productes de posicionament, i quin és el seu acompliment i evolució respecte dels seus serveis antecessors i el dels seus competidors. Entre els serveis de posicionament emergents, resulta d'especial interès el proporcionat per la constel·lació Europea de GALILEO, la qual està a prop d'arribar a la seva completa capacitat operacional, i que resulta prometedora quant als seus requisits de prestacions a nivell usuari, que poden obtenir-se mitjançant l'ús dels senyals del seu servei obert: E1, E5a i E5b. D'entre els sistemes ja existents, el més destacat és el proporcionat per la constel·lació Nord-americana de GPS, el qual ha estat permetent amb el senyal C / A un servei de posicionament estàndard i un servei de posicionament precís amb el senyal P per a fins militars. A més a les evolucions del sistema GPS planegen transmetre un servei civil amb senyals més robustes, com pot ser la L5. L'objectiu d'aquest treball és comparar els serveis oberts de posicionament de les constel·lacions de GPS i GALILEO, mitjançant l'anàlisi de les seves prestacions de precisió i integritat obtingudes d'una campanya d'observació, on les dades de referència a utilitzar són la xarxa d'estacions del IGS. La metodologia de posicionament a implementar és el post-processat d'observables de pseudo-rang mono-freqüència en manera estàtica. Per assolir aquest objectiu, l'esforç principal estarà enfocat en el desenvolupament d'una eina SW totalment configura-ble per l'usuari, que sigui capaç de processar els observables de pseudo-rang proporcionats pel marc de referència espacial que formen els satèl·lits de GPS i GALILEO, per posteriorment obtenir les posicions del receptor per mitjà d'un algoritme d'estimació per mínims quadrats. Els resultats que s'obtinguin d'aquest processament seran transmesos a altres eines d'anàlisi, les quals es desenvoluparan també en el marc d'aquest projecte, amb la finalitat de resumir i presentar de manera gràfica les prestacions obtingudes de la campanya. Finalment, amb el suport d'aquests resultats, s'exposaran les conclusions sobre l'acompliment i l'evolució dels serveis anteriorment comentats.

Global Navigation Satellite Systems (GNSSs) are theoretically able to provide accurate, three-dimensional, and continuous positioning to an unlimited number of users. An important shortcoming of GNSS is the lack of integrity, defined as the ability of a system to provide timely warnings in case of malfunction; this problem is especially felt in safety-of-life applications such as aviation. A common way to fill this gap is the use of Receiver Autonomous Integrity Monitoring (RAIM) techniques, which are able to provide integrity information by analyzing redundant measurements. A possible RAIM functionality is the ability to identify, and so discard, anomalous measurements; this functionality has made RAIM very useful also in case of severe signal degradation, such as in urban or dense vegetation areas, where blunders are common. PANG-NAV is a tool, developed by the PArthenope Navigation Group, able to process GNSS measurements (from RINEX files) in order to obtain a position solution. The core of PANG-NAV is the single point positioning (SPP) technique, including a RAIM functionality. A multi-constellation solution, with GPS and Galileo, can be provided. Both static processing and kinematic processing are possible, and in cases where ground truth is available, error analysis can be carried out.

We present a new technique for estimating the absolute vertical and slant total electron content (TEC). The estimation is based on single-frequency joint phase and pseudorange GPS/GLONASS measurements at single stations. Estimated single-frequency vertical TEC agrees qualitatively and quantitatively with the dual-frequency vertical TEC. For analyzed stations a typical value of the difference between the single-frequency vertical TEC and dual-frequency ones generally does not exceed ~1.5 TECU with RMS up to ~3 TECU.

Precise point positioning is increasingly being used in geodetic applications that in many cases are based on static 24-hour RINEX files. Since there are many applications where sub-centimeter position accuracy is not required and users wish to use a single receiver and not be dependent on differential correction, we will evaluate PPP performance for static positioning with 12-, 6-, 3-, 1- and ½-h observations. We have, therefore, considered a dataset for the year 2013 from 14 European GNSS stations. The data were analyzed using GIPSY-OASIS II software package and evaluated in terms of repeatability of the coordinates and of coherence with the formal error indicated for each PPP solution. Particular attention was paid to solutions showing large discrepancies in coordinates. The test shows that PPP precision for the 24-h files is below 5 mm, but decreases slightly for the 12-, 6- and 3-h observation sets. For the 1-h and the ½-h RINEX files, precision is within 5 and 10 cm, respectively. The analysis is completed with a discussion on the impact of the ambiguity resolution that shows how it significantly improves only the easting component and moreover has a higher influence on the formal error rather than on the solutions. Lastly, the study contains an investigation into the reliability of the formal error associated with the PPP solutions. We show that the formal error can be used to identify incorrect solutions, but is not suitable to represent the real accuracy. For that reason, we propose to use the formal error given for the float solutions even for the ones with fixed ambiguities.

Denne masteroppgaven, skrevet for REALTEK ved Norges miljø- og biovitenskapelige universitet (NMBU), omhandler fagområdet geomatikk; mer spesifikt GNSS-observasjoner med en smartmobil. Hensikten med oppgaven er å analysere rådata fra en Samsung Galaxy S9+, som har kapabilitet for GNSS-måling på én frekvens for flere globale satellittnavigasjonssystemer (GNSS). Målinger fra nærliggende basestasjon ble også brukt i analysen av mobilobservasjonene. Oppgaven fokuseres hovedsakelig på GPS-observasjoner, men noen resultater for Galileo og andre GNSS blir også presentert. Analysen ble hovedsakelig utført vha. programmering ved bruk av Python 3.7. Oppgaven består hovedsakelig av seks hovedkapitler, og i tillegg noen vedlegg. Kap. 1 Introduksjon: Historikk rundt temaet mobil GNSS, problemstillinger, motivasjon, forklaringer og tidligere, relevant forskning. Kap. 2 Teori: Relevant teori for oppgaven; formler, illustrasjoner og forklaringer. Kap 3 Datainnsamling og metode: Beskrivelse av hvordan rådata ble anskaffet i praksis, og hvordan disse ble analysert. Kap. 4 Resultater: Plott og tabeller som resulterte fra analyse av rådata. Kap. 5 Diskusjon: Tolkning av resultater og generell refleksjon rundt oppgaven. Kap 6. Konklusjon: Endelige svar på oppgavens problemstillinger og forslag til videre arbeid rundt temaet. Først i oppgaven presenteres den moderne mobilen og hvordan den har utviklet seg blant allmennheten. Mobiltelefonen var først forbeholdt kommunikasjonsformål, men med tiden har mer og mer teknologi blitt implementert i den lommestore enheten: Bilder, video og – sist, men ikke minst – GPS. Den første GPS-støttende mobilen kom ut i 1999, og siden den tid har satellittbasert navigasjonsteknologi blitt en standard for mobiltelefonen. I 2019, tjue år senere, er det ikke lenger så mye snakk om GPS alene, men heller GNSS (Global Navigation Satellite Systems) – flere satellittbaserte navigasjonssystemer. Forventningene våre til mobilens navigasjonsteknologi har blitt større, men har kvaliteten på målingene – og posisjoneringen – blitt noe bedre? Tidligere har det blant annet blitt forsket på GNSS rådata fra en Nexus 9-tablett (Håkansson, 2018) og en Huawei P10 (Lachapelle et al., 2018). For Nexus 9 ble det oppnådd flytløsninger med statisk måling som resulterte i 3D-presisjoner over 40 cm. Fra tilsvarende resultater for Huawei P10 ble det konkludert at kontinuerlig fasemåling var "dårlig i de fleste tilfeller" (ibid.). Med nye utviklerinnstillinger i Android 9 har derimot kontinuerlig fasemåling blitt forbedret: Det er nå mulig å skru av GNSS-relaterte driftssykluser som tidligere har skapt fasebrudd. For anskaffelse av data i oppgaven ble det målt to individuelle punkter; AUDM og STRB, i tidsintervaller på to timer hver. AUDM befinner seg blant bygninger og en stor vannflate, mens STRB står på en øde fotballbane. Punktene ble med hensikt plassert i disse omgivelsene slik at det ene punktet ble mer utsatt for multipath enn det andre. Etter måling ble rådataene analysert og prosessert: Python 3.7 ble brukt til analysering og plotting, mens RTKLIB og SKTrans henholdsvis ble brukt til punktprosessering og -transformering. Plott og tabeller viser resultatene fra målingene. Antall satellitter målt fra viste seg å være over 30; ofte rundt 10 for GPS og GLONASS, og 3-6 for Galileo. GPS-satellittenes baner blir også visualisert ved bruk av himmelplott. Støyen på koden hos mobilen er, som ventet, langt høyere enn den hos geodetisk mottaker. Videre resulterer punktestimater fra koden på flere meter i presisjon og nøyaktighet, mens fasemålingene ga presisjonsmål på godt under centimeteren. Fasebrudd opptrådde flere ganger i måleintervallene, men det var mulig å opprettholde heltallsflertydighetene over lenger tidsintervaller. Dette resulterte i statiske fix-løsninger med 3D-presisjon på under 5 mm for punktene AUDM og STRB. Dette var et uventet bra resultat, og det kan muligens bli bedre – fasesenteret bør blant annet bestemmes. Det kan forventes en romlig presisjon på 10-20 meter ved prosessering av støyete kodemålinger. Høydekomponenten blir som forventet dårligst. Inkludering av Galileo forbedrer kodeløsningen noe. Videre kan midling av kodebestemte punkter gi en nøyaktighet på 1.5 og 3 meter i grunnriss og høyde, respektivt. For fix-løsninger med statisk måling ble resultatet over all forventning: En romlig presisjon på under 5 mm kan oppnås med mobilens fasemålinger. Fix-løsningene bommet fremdeles på selve punktet med ca. 6 cm nord og 3-4 cm vest, men dette skyldes først og fremst at mobilens fasesenter er ukjent. PCO kan tilnærmes ved å utføre veldig nøyaktige, statiske målinger – mulig ved høy presisjon. Resultatene oppnådd i denne oppgaven virker lovende for mobilbasert GNSS i fremtiden. This master thesis, written for REALTEK at the Norwegian University of Life Sciences (NMBU), deals with the field of study that is geomatics; more specifically GNSS observations from a smartphone. The purpose of this thesis is to analyze raw measurements from a Samsung Galaxy S9+, which has the capability to measure on one frequency for multiple global navigation satellite systems (GNSS). Measurements from a nearby base station were also used in the analysis of the smartphone observations. The thesis focuses mainly on GPS observations but some results from Galileo and other GNSS are also presented. The analysis part was mainly accomplished by programming in Python 3.7. The study consists of six main chapters, but also some appendices. Chp. 1 Introduction: Some history concerning mobile GNSS, issues for the thesis, motivation, explanations and former studies on the topic. Chp. 2 Theory: Relevant theory for the thesis; formulas, illustrations and explanations. Chp. 3 Data acquisition and method: Explanations on how the raw measurements were obtained, practically, and how they were analyzed. Chp. 4 Results: Plots and tables as products from the analysis. Chp. 5 Discussion: Interpretations of the results and general reflections on the thesis. Chp. 6: Conclusion: Final answers on the issues raised in the thesis, and proposals on relevant fields to study. Firstly, the thesis presents the modern cellphone and how it has developed among people in general. The mobile phone was mainly reserved for communication purposes, but with time, more and more technology has been implemented in the pocket-sized device: Pictures, video and – finally – GPS. The first GPS-supporting cellphone was launched in 1999, and since then, satellite-based navigation technology has become a standard in cellphones. In 2019, twenty years later, we are not only interested in GPS alone, but rather GNSS – multiple satellite-based navigation systems. Our expectations regarding mobile-based navigation technology have become bigger, but has the quality of the measurements – and the positioning – become any better? Other related field studies include research on GNSS raw measurements from a Nexus 9 tablet (Håkansson, 2018) and a Huawei P10 (Lachapelle et al., 2018). For a Nexus 9, float solutions from static measurements were achieved, resulting in precisions above 40 cm. From similar results for Huawei P10, it was concluded that “carrier phase measurement continuity was poor in most instances” (ibid.). However, with newly available developer settings in Android 9, continuous phase-measuring has been improved: GNSS-related duty-cycling, which was the main cause of cycle slips in the past, can now be turned off. For the data acquisition in the thesis, two points were measured; AUDM and STRB, over the span of two hours each. AUDM is located among some buildings and next to a water surface, while STRB is situated on an open soccer field. The points were placed in these environments on purpose, so that one point is more exposed to multipath than the other. After data acquisition, the data were analyzed and processed: Python 3.7 was used for analyzing and plotting, while RTKLIB and SKTrans were respectively used for point-processing and transformation. Plots and tables show the results from the measurements. The total number of satellites synced can reach over 30; often 10 GPS and GLONASS satellites, and 3-6 Galileo satellites. GPS orbits are also visualized by a sky plot. The smartphone code noise is, as expected, far greater than that of a geodetic receiver. Further, estimates from the code resulted in precisions in the meter range, while static carrier phase measurements resulted in sub-centimeter precision. Cycle slips appeared in multiple instances during measurements, however, multiple fix amibiguities were maintained for longer periods of time. This resulted in static fix solutions with 3D precisions below 5 mm for the points AUDM and STRB. These were unexpectedly good results, and they can probably be improved – the PCO should be estimated. A spatial precision of approximately 10-20 meters can be expected from the noisy code estimates. The height estimate is worst, as expected. The inclusion of Galileo improves the code estimates to an extent. Further, by averaging multiple code estimates, a horizontal and vertical accuracy of about 1.5 and 3 meters can be achieved, respectively. For static estimates, the results went beyond all expectations: A spatial precision below 5 mm can be achieved from the smartphone phase measurements. The accuracy is still off by some centimeters, mostly due to the unknown PCO. M-GEOM

A preliminary analysis of Galileo F/NAV broadcast Clock and Ephemeris is performed in this paper with 43 months of data. Using consolidated Galileo Receiver Independent Exchange (RINEX) navigation files, automated navigation data monitoring is applied from 1 January 2017 to 31 July 2020 to detect and verify potential faults in the satellite broadcast navigation data. Based on these observation results, the Galileo Signal-in-Space is assessed, and the probability of satellite failure is estimated. The Galileo nominal ranging accuracy is also characterized. Results for GPS satellites are included in the paper to compare Galileo performances with a consolidated constellation. Although this study is limited by the short observation period available, the analysis over the last three-year window shows promising results with Psat = 3.2 &times, 10&minus, 6/sat, which is below the value of 1 &times, 5 stated by the Galileo commitments.

The Quasi-Zenith Satellite System (QZSS), a dedicated regional Japanese satellite system currently under development, was designed to complement the performance of the Global Positioning System (GPS). The high elevation angle of the QZSS satellite is expected to enhance the effectiveness of GPS in urban environments. Thus, the work described in this paper, aimed to investigate the effect of QZSS on GPS performance, by processing the GPS and QZSS measurements recorded at the Bohyunsan reference station in South Korea. We used these data, to evaluate the satellite visibility, carrier-to-noise density (C/No), performance of single point positioning, and Dilution of Precision (DOP). The QZSS satellite is currently available over South Korea for 19 hours at an elevation angle of more than 10 degrees. The results showed that the impact of the QZSS on users’ vertical positioning is greatest when the satellite is above 80 degrees of elevation. As for Precise Point Positioning (PPP) performance, the combined GPS/QZSS kinematic PPP was found to improve the positioning accuracy compared to the GPS only kinematic PPP.

Geoscience and Remote Sensing Society (GRSS);The Institute of Electrical and Electronics Engineers (IEEE), 38th Annual IEEE International Geoscience and Remote Sensing Symposium, IGARSS 2018 -- 22 July 2018 through 27 July 2018 -- -- 141934, The global positioning system (GPS) can navigate and position at any time and weather conditions, but subject to a variety of error sources. The most important one of these errors is the ionospheric delay when the GPS signals propagate through the ionosphere. The first order ionospheric effects can be removed using dual frequency GPS receivers, while the higher order ionospheric (HOI) effects are much smaller than the first order effects, which are generally neglected. However, under highly active solar activities condition, high order ionospheric effects may be big and should be eliminated. In this study, the high order ionospheric effects on 3D GPS coordinate components was investigated with 30 days (June 2011) of GPS data at 8 GPS stations in Turkey. Firstly, the high order ionospheric effects were corrected in the RINEX observation file, and then raw and corrected observations were processed in GAMIT software to obtain precise coordinate components. Results show that average 10, 7 and 24 millimeters changes occurred in the north, east and up components by high-order ionospheric effects, respectively. During the peak solar activity days in 2011, it is observed that the high-order ionospheric effects in the north, east and up components can reach 18, 11 and 43 millimeters change, respectively. © 2018 IEEE

The forests are home of two thirds of the red listed species in Norway. To safeguard these species when doing forest management, it is important to know where their respective biotopes are. When mapping species the Global Navigation Satellite System (GNSS) is often used. However, forest canopies also represents a challenge for this technology. In Norway, volunteers and hobbyists do most species mapping and it is expected that mappers will apply smartphones for obtaining coordinates in the future. This thesis assess how smartphones, as GNSS units, function under forest canopies. M-ECOL

Rastući broj tehnoloških i društveno-ekonomskih sustava se zasniva na satelitskom određivanju položaja, npr. snalaženje u prostoru, analiza prometnih puteva, pridjeljivanje vremensko-položajnih žigova financijskim transakcijama itd. Kvaliteta usluge određuje se točnošću procjene položaja satelitskim sustavima. Ovaj rad obuhvaća analizu (referentnog) postupaka procjene položaja u domeni navigacijske primjene te se otkrivaju potencijalne slabosti i predlaže poboljšanje. Analiza algoritma uključuje izvedbu i ocjenu kvalitete izvedbe algoritma korištenjem izmjerenih pseudoudaljenosti i programski određenog GPS prijemnika. Programski određen GPS prijemnik je praktično izveden na osobnom računalu. Korišten je u svrhu obrade prikupljenih opažanja GPS prijemnika u RINEX podatkovnom formatu za ulaz u izvedbe. Opažanja su prikupljena s referentne međunarodne GNSS stacionarne postaje (engl. International GNSS Service Reference Station, IGS Reference Station) u Padovi, Italija. Poboljšanja algoritma analizirana su usporednom analizom poboljšanog i izvornog algoritma. Uvodnim se poglavljem uvodi u svijet globalnih satelitskih navigacijskih sustava (engl. Global Navigation Satellite System, GNSS) te se formuliraju ciljevi rada. Prvo poglavlje detaljnije opisuje jedan odabran GNSS, Globalni pozicijski sustav (GPS), i uvodi i egzaktno definira problem određivanja položaja u domeni navigacijske primjene. Odabrani GNSS se koristi pri prikupljanju eksperimentalnih podataka. Drugo poglavlje opisuje načine pronalaska rješenja problema određivanja položaja definiranog prvim poglavljem. Pri prikupljanju i predobradi eksperimentalnih podataka koristi se GNSS korisnička oprema zasnovana na programski određenom radiju. Opis programski određenog radija i korištene GNSS korisničke opreme nalazi se u trećem poglavlju. Četvrto poglavlje donosi praktičnu izvedbu osnovnog (referentnog) algoritma za procjenu položaja u domeni navigacijske primjene, razloge za njegovo poboljšanje te izvedbu i opis poboljšanja. Peto poglavlje ocjenjuje i uspoređuje kvalitetu dva izvedena algoritma, osnovnog i poboljšanog, nakon čega slijede zaključci. Satellite positioning has been recognised as an fundamental underlying technology for growing number of modern technology and socio-economic systems, i.e. orientation in space, traffic routes analysis time and space stamping of financial transactions etc. The quality of services provided by those systems relies on the satellite positioning performance, especially positioning accuracy. This paper covers the analysis of (reference) position estimation procedures in the navigation application domain, discovering of potential weaknesses and suggesting the improvement. The algorithm analysis involves practical performance and rating of the algorithm performance quality using measured pseudorange and programmable GPS receiver. A program-specific GPS receiver is practically performed on a personal computer. It was used for processing the GPS receiver’s observations in the RINEX data format to form the input of the algorithm performance. GPS receiver’s observations are collected from IGS reference station located in Padua, Italy. Algorithm enhancements were analyzed by a parallel analysis of the improved and original algorithm. The introductory chapter introduces the world of global navigation satellite systems (GNSS) and formulates the objectives. Chapter one details a selected GNSS, Global Positioning System (GPS), and introduces and defines the problem of positioning in the navigation application domain. Selected GNSS is used when collecting experimental data. The second chapter describes solution finding methods of the problem defined by chapter one. GNSS user equipment based on program-specific radio is used when collecting and pre-processing experimental data. The description of the programmable radio and the GNSS user equipment used are given with the third chapter. Chapter Four provides a practical performance of the basic (benchmark) algorithm for position assessment in the navigation application domain, the reasons for its improvement and performance and description of the improvement. The fifth chapter evaluates and compares the quality of two derived algorithms, basic and improved, followed by conclusions.

IEEE Geoscience and Remote Sensing Society (GRSS), 37th Annual IEEE International Geoscience and Remote Sensing Symposium, IGARSS 2017 -- 23 July 2017 through 28 July 2017 -- -- 133497, The precipitable water vapor (PWV) can be estimated from dual-frequency GPS observations, which has been widely used for atmospheric study and weather forecasting. However, high-order ionospheric delays are normally ignored in GPS applications. In this paper, high-order ionospheric effects on GPS-estimated precipitable water vapor are investigated from 30 days of GPS data in June 2011 at 8 GPS stations in Turkey. Firstly, the second- and third-order effects on GPS data are corrected in RINEX using IGRF11 model, and then the precipitable water vapor (PWV) is obtained from raw and corrected RINEX data with GAMIT software. Results show that high-order ionospheric effects are up to 1 millimeter on PWV during this period. Solar activity is an important effect on ionospheric activities. When data during the peak solar activity days are used for same stations in 2011, high-order ionospheric effects on PWV is increasing, while low solar activities, high-order ionospheric effects are much smaller. © 2017 IEEE.

The contribution describes the basic principles of measurement and the use of global positioning systems, focusing on the most widely used system NAVSTAR, including used protocols. It deals NMEA protocols-which today ranks among the most widespread GPS system, RINEX-which is an interpretation of "raw" data, these systems, and RTCM-which is an alternative for NMEA with the difference that is much used in the GLONASS system. © Research India Publications.

This paper investigates the potential vertical guidance performance of global positioning system (GPS)/wide area augmentation system (WAAS) user avionics sensor when the modernized GPS and Galileo are available. This paper will first investigate the airborne receiver code noise and multipath (CNMP) confidence (σair). The σair will be the dominant factor in the availability analysis of an L1-L5 dual-frequency GPS/WAAS user avionics sensor. This paper uses the MATLAB Algorithm Availability Simulation Tool (MAAST) to determine the required values for the σair, so that an L1-L5 dual-frequency GPS/WAAS user avionics sensor can meet the vertical guidance requirements of APproach with Vertical guidance (APV) II and CATegory (CAT) I over conterminous United States (CONUS). A modified MAAST that includes the Galileo satellite constellation is used to determine under what user configurations WAAS could be an APV II system or a CAT I system over CONUS. Furthermore, this paper examines the combinations of possible improvements in signal models and the addition of Galileo to determine if GPS/WAAS user avionics sensor could achieve 10 m Vertical Alert Limit (VAL) within the service volume. Finally, this paper presents the future vertical guidance performance of GPS user avionics sensor for the United States’ WAAS, Japanese MTSAT-based satellite augmentation system (MSAS) and European geostationary navigation overlay service (EGNOS).

Submitted by Boris Flegr (boris@uerj.br) on 2021-01-06T14:05:13Z No. of bitstreams: 6 Luis Felipe Buarque Pt 1.pdf: 218105 bytes, checksum: 780ad3ae43525aab15f32dce920223f0 (MD5) Luis Felipe Buarque Pt 2.pdf: 1776290 bytes, checksum: 69cf0371895bef769513338c65c2cbb2 (MD5) Luis Felipe Buarque Pt A 1 a 5.pdf: 911475 bytes, checksum: 70cfc86f5eb539f69c7bf7c3f8566a28 (MD5) Luis Felipe Buarque Pt A 6.pdf: 148395 bytes, checksum: 9b9884a8565283819088598783eefe64 (MD5) Luis Felipe Buarque Pt A 7.pdf: 71775 bytes, checksum: 1091799b766b9afa735f7edd9487e2cc (MD5) Luis Felipe Buarque Pt A 8 e 9.pdf: 268303 bytes, checksum: 95ec423748bb27ca73a646e68c0b7fe5 (MD5) Made available in DSpace on 2021-01-06T14:05:13Z (GMT). No. of bitstreams: 6 Luis Felipe Buarque Pt 1.pdf: 218105 bytes, checksum: 780ad3ae43525aab15f32dce920223f0 (MD5) Luis Felipe Buarque Pt 2.pdf: 1776290 bytes, checksum: 69cf0371895bef769513338c65c2cbb2 (MD5) Luis Felipe Buarque Pt A 1 a 5.pdf: 911475 bytes, checksum: 70cfc86f5eb539f69c7bf7c3f8566a28 (MD5) Luis Felipe Buarque Pt A 6.pdf: 148395 bytes, checksum: 9b9884a8565283819088598783eefe64 (MD5) Luis Felipe Buarque Pt A 7.pdf: 71775 bytes, checksum: 1091799b766b9afa735f7edd9487e2cc (MD5) Luis Felipe Buarque Pt A 8 e 9.pdf: 268303 bytes, checksum: 95ec423748bb27ca73a646e68c0b7fe5 (MD5) Previous issue date: 2011-10-10 The use of positioning techniques for high -precision and precision, using the Global Positioning System, have been established as a permanent solution to obtain the coordinates of points on the surface, in several applications, particularly those involved in completion of the registration in urban areas and construction of the database associated with Geographic Information Systems used in land management. GPS receivers store the information of the satellites in own format initially, but most users do not use this format to work, but the RINEX format. Since this is an important format to work with GPS, the proprietary software that usually accompany the receivers and make the transformation of its own format to RINEX, the observable process in an exclusive and closed, not allowing change your source code (which sets up a "black box "). This work aims to develop and implement a program with open source code for reading and manipulating files transmitted ephemeris and precise Global Positioning System - GPS and apply it to the position of artificial satellites, and also a study of the behavior of the same in geodetic positioning of points on Earth's surface. Considering that the ground position of the satellites directly influences the calculation of the position of points on the surface, this study finds that it is possible to get coordinates from the satellite ephemeris transmitted consistently, and this is done using the processing that the program is to properly handle the RINEX files. The program implemented is capable of handling files in format RINEX and SP3: reading, extracting and using information to an application of terrestrial positioning GPS satellites, and may also perform other applications such as geodetic positioning points of adapting the source code for other models. The program may be used for the benefit of professionals working in various applications involving satellite geodetic positioning, providing flexibility to work because the program will be open source. O emprego das técnicas de posicionamento de alta-precisão e de precisão, com recurso ao Sistema de Posicionamento Global, têm se consolidado como solução definitiva para a obtenção das coordenadas de pontos sobre a superfície terrestre, nas mais diversas aplicações, em particular aquelas envolvidas na realização do cadastro em áreas urbanas e construção da base de dados associada aos Sistemas de Informação Geográfica utilizados na gestão territorial. Os receptores GPS armazenam as informações dos satélites inicialmente em formato próprio, porém a maioria dos usuários não usa esse formato para trabalho, e sim o formato RINEX. Sendo este um formato importante ao trabalhar com GPS, os softwares proprietários que geralmente acompanham os receptores e fazem a transformação de seu formato próprio para o RINEX, processam as observáveis de forma exclusiva e fechada, não permitindo alteração de seu código-fonte (o que configura uma caixa preta ). Este trabalho visa elaborar e implementar um programa com código-fonte aberto para leitura e manipulação de arquivos de efemérides transmitidas e precisas do Sistema de Posicionamento Global GPS e aplicá-lo ao posicionamento de satélites artificiais, e ainda realizar um estudo do comportamento do mesmo no posicionamento geodésico de pontos na superfície terrestre. Considerando-se que a posição terrestre dos satélites influencia diretamente no cálculo da posição de pontos sobre a superfície, esse estudo verifica que é possível obter coordenadas dos satélites a partir das efemérides transmitidas de forma coerente, e isto é feito utilizando-se o processamento que o programa faz ao manipular corretamente os arquivos RINEX. O programa implementado é capaz de lidar com os arquivos de formato RINEX e SP3, lendo, extraindo e utilizando informações para uma aplicação de posicionamento terrestre de satélites artificiais GPS, podendo ainda realizar outras aplicações como o posicionamento geodésico de pontos adaptando seu código-fonte para outros modelos. Esse programa poderá ser utilizado em benefício dos profissionais que atuam em diversas aplicações que envolvam o posicionamento geodésico por satélites, proporcionando flexibilidade de trabalho, pois o programa terá código-fonte aberto.

The use of airborne scanners involves geo-referencing problems, which are difficult because of the need to know the exact platform position and attitude for each scan line. The errors of the onboard navigation system are normally corrected using ground control point on the image. This post-processing correction procedure is too long in case of multiple flight campaigns, and besides it implies the need to have available 1:10000 orthophotoimages or maps in digital format. To optimize the above procedure a new method to correct MIVIS navigational data in the post-processing phase has been implemented. The procedure takes into consideration the GPS stream in Rinex format of common knowledge and findable on the web, acquired at the ground stations of the Geodetic Data Archiving Facilities provided by ASI. The application of this correction entails the assumption that the environmental variables affecting both onboard and geodetic GPS equally affect the position measurements. The airborne data correction was carried out merging the two data sets (onboard and ground station GPS) to achieve a more precise aircraft trajectory. The present study compares the geo-coded images obtained by means of the two post-processing methods.

In this paper the absolute calibration of GPS time receivers with a Spirent GPS/Galileo HW simulator is analyzed and described in detail. The primary step is to calibrate the simulator itself. In this context the most important facts and values which have to be measured are explained. After the calibration of the simulator the receiver is fed with satellite signals generated by the simulator belonging to a standard GPS satellite constellation to determine the absolute offset of the receiver (internal delay) compared to the simulator output. The used GNSS hardware simulator provides GPS and Galileo signals in parallel and therefore additionally can be used for absolute calibration of combined GPS/Galileo or stand alone Galileo time receivers. As there are no such receivers available yet, the precision of the GPS and Galileo pseudoranges determined by a combined GPS/Galileo receiver is analyzed.

For many applications, access to unbiased or error-controlled global positioning system (GPS) observations can be very useful. This paper is devoted to the description of simulated GPS observations generator (SiGOG), a software that simulates GPS observations. It presents the results of tests of SiGOG accuracy using GPS processing software, and demonstrates its successful performance as a differential GPS (DGPS) correction provider., Facultad de Ciencias Astronómicas y Geofísicas