GENERATION AND PERFORMANCE ANALYSIS OF GPS AND GLONASS VIRTUAL DATA FOR POSITIONING UNDER DIFFERENT IONOSPHERIC CONDITIONS

Several approaches concerning the use in positioning of GNSS (Global Navigation Satellite Systems) can be considered: systems, applied methods and errors that can affect the signals. Following the GLONASS (GLObal NAvigation Satellite System) constellation reestablishment (2011), there was renewed interest in its use with GPS (Global Positioning System). Different possibilities are available concerning applied methods, such as the virtual reference station (VRS) concept (it is possible to obtain data for a virtual station that does not physically exist, using data from a network). One of the main sources of error related to the GNSS signal, is the ionosphere. Many studies have been developed aiming to evaluate GPS positioning quality and influences that can affect it, but there are still several investigation possibilities concerning GLONASS. In this context, this research is intended to assess the GPS/GLONASS virtual data positioning performance considering regions and periods with different ionospheric behavior. A high correlation between the results from virtual and real data (Pearson’s correlation coefficients around 0.8) was noticed. GPS/GLONASS data performance presented better mean squared error results compared to GPS alone (average 3D improvement was 45 cm - 49%). In addition, it was possible to verify ionosphere influence in the positioning error, taking into account station region and period of the year

ASSESSMENT OF GPS/GLONASS POINT POSITIONING IN BRAZILIAN REGIONS WITH DISTINCT IONOSPHERIC BEHAVIOR

Nowadays GPS (Global Positioning System) and GLONASS (GLObal NAvigation Satellite System) are the main systems of GNSS (Global Navigation Satellite Systems), also composed by Galileo and BeiDou. After a long period of degradation, GLONASS was modernized, and its constellation was reestablished in 2011. Considering this new scenario, with GPS and GLONASS full constellations, the interest in the combined use of both systems was renewed. Besides the constellations used, other factors are related to the positioning quality, for instance the ionospheric influence. Several studies have been performed aiming to assess GPS positioning quality as well as the ionospheric influence on it, but concerning GLONASS, there are still several possibilities of investigation. In this context, this research aimed to assess the GPS/GLONASS data point positioning performance considering Brazilian regions with different ionospheric behavior during periods of low and high ionospheric activity. Spatial and time ionospheric influence in the positioning performance were observed. Considering all configurations tested with 30-minute data, the use of GPS/GLONASS data provided better results in 97.35% of the cases when compared to autonomous GPS, the mean improvement was about 60 cm, which corresponds to 30%

GENERATING GPS PSEUDORANGE DATA FOR A VIRTUAL STATION: METHODS, IMPLEMENTATION, AND ANALYSIS OF RESULTS

O objetivo deste artigo é avaliar a qualidade das observáveis de pseudodistância geradas para uma estação de referência virtual (VRS - Virtual Reference Station). Para gerar os dados da VRS três métodos diferentes foram implementados e testados. No primeiro método, foram empregados os dados brutos das estações de referência da rede. O segundo foi baseado nas correções de duplas diferenças das estações de referência. No terceiro método, foram utilizados modelos atmosféricos (ionosfera e troposfera) para gerar os dados da VRS. As estações da rede do estado de São Paulo foram utilizadas para realizar os experimentos. A VRS foi gerada na posição de uma estação de referência (arquivo real), com coordenadas conhecidas. Para avaliação, os dados da VRS foram comparados com aqueles provindos do arquivo real. Os resultados obtidos foram similares, proporcionando acurácia decimétrica ou centimétrica, dependendo do método.This paper aims to evaluate the quality of the pseudorange observables generated for a Virtual Reference Station (VRS). In order to generate the VRS data three different approaches were implemented and tested. In the first one, raw data from the reference station network were used while in the second it was based on double difference reference station corrections. Finally, in the third approach atmospheric models (ionosphere and troposphere) were used to create the VRS data. Sao Paulo State Network stations were used in all experiments. The VRS data were generated in a reference station position of known coordinates (real file). In order to validate the approaches, the VRS data were compared with the real data file. The results were quite similar, reaching the decimeter or centimeter level, depending on the approach applied

KLOBUCHAR AND NEQUICK G IONOSPHERIC MODELS COMPARISON FOR MULTI-GNSS SINGLE-FREQUENCY CODE POINT POSITIONING IN THE BRAZILIAN REGION

One of the main error sources in GNSS positioning comes from the ionosphere, an atmospheric layer that stays in the signal path between the satellite and the receiver. For single frequency positioning, the ionospheric effects can be minimized by using an ionospheric model e.g. Klobuchar or NeQuick G. These models are respectively associated to GPS and Galileo systems through their navigation messages, which broadcast coefficients that describe the worldwide ionospheric behavior, and the calculated ionospheric delay is then applied in the pseudorange observations. In this paper, it is presented a comparison between these two models in multi-GNSS (GPS and Galileo) single frequency point positioning, considering two Brazilian stations at different magnetic latitudes, and covered months of weak and strong ionospheric activity from 2013 to 2018. The results indicate a better performance of NeQuick G model compared to the Klobuchar. Considering all the analyzed periods and stations, Klobuchar improves the positioning accuracy in 16% and 50% in periods of weak and strong ionospheric activity, respectively, while NeQuick G improves the accuracy in 31% and 55%

Análise do Posicionamento por Ponto Preciso com Dados GPS e GLONASS em Diferentes Latitudes

O GNSS (Global Navigation Satellite System) possui, atualmente, dois sistemas completos, o GPS (Global Positioning System) e o GLONASS (GLObal NAvigation Satellite System). Apesar de terem sido desenvolvidos de forma simultânea, os sistemas apresentam características diferentes. Além disso, o GLONASS passou por um longo período de degradação, o que por muito tempo causou uma lacuna nas investigações realizadas sobre o mesmo. No entanto, em 2011 o GLONASS teve sua constelação restabelecida, renovando o interesse em estudos relacionados ao seu desempenho. No presente trabalho foi investigada a performance dos sistemas GPS e GLONASS de forma autônoma e combinada, considerando estações GNSS em diferentes regiões (latitudes), sendo avaliados os erros obtidos na posição, o número de satélites visíveis e a quantidade de observações coletadas. Em todos os casos considerados, o uso de dados combinados levou a melhores resultados. Em 25% das estações utilizadas o GLONASS apresentou resultados médiosmelhores que o GPS, considerando o posicionamento autônomo

ASSESSMENT OF NEUTRAL ATMOSPHERIC DELAY PREDICTIONS BASED ON THE TEMPORAL RESOLUTION OF AN ATMOSPHERIC MODEL

In Global Navigation Satellite Systems (GNSS), the effects of neutral atmosphere in electromagnetic signal propagation impacts directly on the quality of the final estimated position, leading to errors in the metric order. Using an atmospheric model is a good strategy to minimize these errors, because it becomes possible to obtain a neutral atmospheric delay with the same spatial and temporal resolution, taking into consideration particularities of the atmosphere treated by a numerical model. The regional model of the Center for Weather Forecasting and Climate Studies (CPTEC) used in this paper has a spatial resolution of 15 km and a temporal resolution of 3 hours. Usually, the delay prediction of 3 hours is interpolated in time to GNSS applications and this can influence the quality of the values obtained in each interpolated epoch. Higher temporal resolutions can lead to lower errors in the final position. In this paper, the quality of delay predictions is evaluated for this atmospheric model with resolutions of 6 and 3 hours. The estimated delay, derived from meteorological data in the same location as the geodetic data, is considered as “truth”. The temporal resolution of 3 hours shows better results than using 6 hours, particularly for the hydrostatic component in the initial prediction period, RMSE of 1.25 cm was reduced to 0.2 cm in NEIA station

RANCANG BANGUN MEKANISME PITCH BLADE CONTROL DAN YAW DRIVE CONTROL TURBIN ANGIN HORISONTAL DIAMETER SUDU 10 M

ABSTRAK Salah satu penyebab langkanya sumber daya alam di dunia ini adalah semakin tingginya kebutuhan minyak dan gas (migas). Sementara tingginya migas tidak diimbangi dengan produksi dan sumber energi fosil memiliki kapasitas terbatas. Oleh sebab itu, dibutuhkan sumber daya energi yang terbarukan seperti energi angin, energi matahari, energi panas bumi, energi air, energi biomassa. Dalam kasus ini rancang bangun turbin angin merupakan salah satu solusi untuk mengatasi masalah ini dan kami melanjutkan proyek Tugas Akhir Rancang Bangun Rotor Turbin Angin Horizontal yaitu memfokuskan pada Rancang Bangun Mekanisme Pitch Blade Control dan Yaw Drive Control Turbin Angin Horizontal Diameter Sudu 10 M. Tujuan laporan ini yaitu untuk mengetahui proses pembuatan mekanisme Pitch Blade Control dan Yaw Drive Control berdasarkan diameter sudu dan dapat menghasilkan putaran pada generator dengan mempertimbangkan kapasitas maksimal listrik yang dihasilkan generator dan ketersediaan komponen-komponen itu sendiri. Mekanisme Pitch Blade Control dan Yaw Drive Control diuji kekuatannya berdasarkan pengujian analisis kualitatif (kekuatan tuas; kekuatan baut flens; kekuatan roda gigi yaw drive) dan pengujiaan analisis kuantitatif (reliabilitas). Mekanisme Pitch Blade Control dan Yaw Drive Control memenuhi standar sesuai dengan pengujiaan analisis kualitatif dan pengujiaan analisi kuantitatif. Oleh karena itu mekanisme tersebut dapat dioperasikan jika mekanisme kelistrikan sudah selesai dan sesuai dengan standar untuk lebih menjaga efisiensi Turbin Angin kapasitas 1 KW (Kilo Watt). Kata Kunci : Mekanisme Pitch Blade Control; Mekanisme Yaw Drive Control; Pembuatan; Pengujian Kualitatif; Pengujian Kuantitatif. ix ABSTRACT One of the causes of the scarcity of natural resources in the world is the increasing demand for oil and gas. While the high level of oil and gas is not balanced with the production and sources of fossil energy has limited capacity. Therefore, renewable energy resources are needed such as wind energy, solar energy, geothermal energy, water energy, biomass energy. In this case the design of a wind turbine is one of the solutions to overcome this problem and we continue the Final Project Project for the Design of a Horizontal Wind Turbine Rotor which focuses on the Design of the Pitch Blade Control Mechanism and Yaw Drive Control Mechanism for Horizontal Wind Turbine Diameter of 10 M. The purpose of this report is to determine the process of making the mechanism of Pitch Blade Control and Yaw Drive Control based on blade diameter and can generate rotation on the generator by considering the maximum capacity of electricity produced by the generator and the availability of the components them selves. The Pitch Blade Control and Yaw Drive Control mechanisms are tested for strength based on qualitative analysis testing (lever strength; flange bolt strength; yaw drive gear strength) and testing of quantitative analysis (reliability). The Pitch Blade Control and Yaw Drive Control mechanisms meet standards in accordance with the testing of qualitative analysis and quantitative analysis testing. Therefore, the mechanism can be operated if the electrical mechanism is completed and in accordance with standards to better maintain the efficiency of a 1 KW (Kilo Watt) Wind Turbine capacity. Keywords: Renewble Energy; Wind Turbine; Pitch Blade Control Mechanism; Yaw Drive Control Mechanism; Manufacture; Qualitative Testing; Quantitative Testing

GERAÇÃO DE VRS A PARTIR DE MODELOS ATMOSFÉRICOS: CONCEITO, IMPLEMENTAÇÃO E RESULTADOS

Nowadays, with the implantation of GNSS (Global Navigation Satellite System)reference station networks, several positioning techniques have been developedand/or improved. Using such kind of network data it is possible to model the GNSSdistance dependent errors and to compute correction terms for the network region.Several methods have been developed to formulate the corrections terms fromnetwork stations data. A method that has been received a great attention is theVirtual Reference Station (VRS). The idea is that the VRS data resemble as much aspossible a real receiver data placed in the same local. Therefore, the user has thepossibility of using the VRS as if it were a real reference station in your proximities,and to accomplish the relative positioning with a single frequency receiver. In thispaper it is described a different methodology applied to implement the VRSconcept, using atmospheric models developed by Brazilian researchers. Besides,experiments for evaluating the quality of generated VRS are presented, showing theefficiency of the proposed method.Atualmente, com a implantação das redes de estações de referência GNSS (GlobalNavigation Satellite System), diversas técnicas de posicionamento têm sidodesenvolvidas e/ou melhoradas. Utilizando os dados dessa rede é possível modelaros erros GNSS dependentes da distância e calcular parâmetros de correção para aregião de abrangência da mesma. Diversos métodos têm sido desenvolvidos paraformular os parâmetros de correção a partir dos dados de uma rede de estações dereferência. Um método que tem se destacado é o que utiliza o conceito de VRS(Virtual Reference Station). A idéia é que os dados da VRS se assemelhem tantoquanto possível com aqueles provenientes de um receptor real colocado no mesmolocal. Assim, o usuário tem a possibilidade de utilizar a VRS como se ela fosse umaestação real existente em suas proximidades, e pode realizar o posicionamentorelativo com um receptor de simples freqüência. Neste artigo é descrita umametodologia diferenciada que foi utilizada para implementar o conceito de VRS,utilizando modelos atmosféricos desenvolvidos por pesquisadores brasileiros. Alémdisso, são apresentados experimentos que avaliam a qualidade da VRS gerada,mostrando a eficiência do método proposto

ANÁLISE DE MODELOS TROPOSFÉRICOS NO POSICIONAMENTO BASEADO EM REDES USANDO O CONCEITO DE VRS

Nos últimos anos, várias técnicas de posicionamento GPS (Global PositioningSystem) vêm sendo desenvolvidas e/ou aprimoradas com interesse de alcançar altaacurácia e produtividade em tempo real. O conceito de redes de estações dereferência além de possibilitar aos usuários das comunidades civis e científicasqualidade e confiabilidade no posicionamento, permite estudos sobre a modelagemda refração troposférica na região da rede. Além disso, dentre as formas detransmissão das correções geradas pela rede ao usuário, destaca-se o conceito deVRS (Virtual Reference Station). Neste método, os dados de uma estação virtual sãogerados nas proximidades do usuário, permitindo realizar posicionamento relativoem linhas de base curta com receptor de simples frequência. Neste artigo é descritaa metodologia para geração de dados da VRS com diferentes modelos troposféricos.Foram realizados testes comparativos nas quatro estações do ano com os modelostroposféricos de PNT/INPE (Previsão Numérica de Tempo/Instituto Nacional dePesquisas Espaciais) e Hopfield. Na análise de qualidade dos dados da VRS, o método PPP (Posicionamento por Ponto Preciso) proporcionou resultadossatisfatórios. Foram observadas melhorias entre os modelos de PNT/INPE eHopfield de 9,75% e 24,2% em média para dias secos e úmidos, respectivamente

50 anos de sinergia entre geodésia espacial e meteorologia: do erro no posicionamento GNSS a aplicações de previsão de precipitação de curtíssimo prazo

The neutral atmosphere (or troposphere) causes refraction in radio frequency signals, which results in errors in Global Navigation Satellite Systems (GNSS) measurements. In meteorology, this effect can represent important measurements of the concentration of atmospheric constituents, especially in regions where conventional high-altitude atmospheric sounding (radiosondes) cannot be performed. There are two GNSS techniques used for this. In the first one, GNSS receivers are located on terrestrial stations that provide estimates of the vertically integrated moisture content (Precipitable Water Vapor - PWV). In the second case, receivers are in space platforms, which obtains profiles of atmospheric pressure, temperature and humidity, known as GNSS radio occultation. These measurements have significant potential for nowcasting applications (30 minutes in advance) of extreme precipitation events (>35 mm). This paper presents a review of the state of the art in the synergy between Geodesy and Meteorology for modeling the neutral atmosphere (neutrosphere), its effect on GNSS positioning and in the estimation of atmospheric constituents, and their applications. Furthermore, it offers the improvements and new challenges developed in modeling the delay for high accuracy positioning.A atmosfera neutra (ou troposfera) causa refração nos sinais de radiofrequência, que resulta em erros nas medidas do Global Navigation Satellite Systems (GNSS) empregadas no posicionamento geodésico. Já para a Meteorologia esse efeito pode representar medidas importantes da concentração dos constituintes atmosféricos, principalmente em regiões onde não se pode realizar sondagem atmosférica convencional, por meio de radiossondas acopladas a balões. Duas técnicas GNSS podem ser empregadas para isso. A primeira utiliza receptores em estações terrestres que fornecem estimativas do conteúdo integrado verticalmente de umidade na atmosfera neutra (Precipitable Water Vapor - PWV). A segunda, com receptores localizados em plataformas espaciais, com os quais obtém perfis atmosféricos de pressão, temperatura e umidade, na técnica conhecida como Rádio-ocultação GNSS. Essas medidas têm um potencial significativo para aplicações em previsões de curtíssimo prazo (30 minutos) de eventos extremos de precipitação (>35 mm). O objetivo principal deste artigo é realizar uma revisão do estado da arte da sinergia entre a Geodésia e a Meteorologia na modelagem da atmosfera neutra (neutrosfera), seu efeito no posicionamento GNSS e na estimativa dos constituintes atmosféricos e suas aplicações. Além disso, apresenta os aprimoramentos e novos desafios desenvolvidos na modelagem do atraso para o posicionamento de alta acurácia