Sniffer para redes Ethernet de tempo-real baseado em FPGA

Mestrado em Engenharia Electrónica e TelecomunicaçõesA crescente utilização de sistemas distribuídos em aplicações de tempo-real tem levado á criação de protocolos de comunicação cada vez mais com- plexos e sofisticados. Apesar da rede Ethernet não apresentar característi- cas de tempo-real, devido ás suas vantagens, têm sido desenvolvidos muitos protocolos de comunicação tempo-real baseados em Ethernet. Nesta disser- tação é analisada a importância das arquitecturas distribuídas em aplicações de tempo-real, sendo apresentados alguns conceitos relacionados com esta problemática. Para avaliar o funcionamento lógico e temporal de uma rede de comuni- cação é necessário utilizar ferramentas, vulgarmente designadas sniffer, que permitem observar o tráfego que nelas circula e os respectivos instantes. Apesar de existirem inúmeras ferramentas deste tipo para Ethernet, o seu desenvolvimento foi conduzido pelos requisitos de redes de dados de uso geral. A maior parte das aplicações existentes destina-se a correr num com- putador convencional, bastando este estar equipado com uma placa de rede vulgar. No entanto, devido á arquitectura dos sistemas computacionais de uso geral, ás suas capacidades multiprogramação e á forma como é efec- tuado o time-stamping das mensagens, estas aplicações não satisfazem as necessidades especificas de alguns protocolos tempo-real, nomeadamente no que concerne á resolução e precisão com que se consegue medir os instantes de transmissão e de recepção das mensagens. Como resposta ás limitações das ferramentas existentes, esta dissertação apresenta um sniffer capaz de responder ás necessidades especificas dos pro- tocolos de tempo-real. Para isso, a recepção, time-stamping e tratamento de mensagens são efectuados com recurso a hardware dedicado. Neste con- texto, tirou-se partido da utilização de dispositivos lógicos programáveis, em particular das FPGAs (Field-Programmable Gate Arrays) e da existência de núcleos sintetizáveis de propriedade intelectual, permitindo implementar de forma relativamente simples a camada MAC de Ethernet utilizando o nú- cleo Xilinx LogiCORE Tri-Mode Ethernet MAC disponibilizado pela Xilinx. Os restantes módulos implementados na FPGA têm como objectivo efec- tuar a escrita das mensagens recebidas e de toda a informação associada na memória para posterior leitura e envio via USB. De modo a intercalar o snif- fer na rede de uma forma o menos intrusiva possível, foi construído um TAP Ethernet, também conhecido por Y-splitter, permitindo efectuar a captura das mensagens em ligações full-duplex. Desta forma os dados são duplica- dos para a FPGA sendo efectuado o seu time-stamping e posterior envio de toda a informação via USB para um PC. Os dados são recolhidos pelo PC e armazenados num ficheiro compatível com o Wireshark, permitindo que a captura seja aberta e analisada com recurso a ferramentas standard. Foram também definidos mecanismos que permitem exportar a informação capturada para ferramentas de cálculo capazes de gerar gráficos e efectuar uma caracterização do tráfego capturado. Quanto aos resultados obtidos é possível concluir que a ferramenta con- struída permite efectuar medições temporais rigorosas, com uma resolução de 10ns e um erro máximo de 100ns. Apresenta no entanto algumas limi- tações ao nível da transferência via USB, podendo a duração da captura ser relativamente limitada. Caso a taxa de transmissão com que a informação é recebida da rede Ethernet seja superior á taxa com que dados são enviados da FPGA para o PC, a capacidade de armazenamento temporário da FPGA atinge os seus limites e a captura é terminada. Por outro lado, as aplicações baseadas em software permitem obter resultados com uma resolução tem- poral de 1¹s e uma incerteza na casa dos milisegundos. Para além disso, em determinadas situações, utilizando ferramentas baseadas exclusivamente em software podem ser perdidas mensagens sem que o utilizador seja alertado deste acontecimento. ABSTRACT: The growing use of distributed systems on real-time applications has origi- nated more and more complex and sophisticated communication protocols. Despite Ethernet network does not have real-time characteristics, due to its advantages, a lot of real-time communication protocols based on Eth- ernet have been developed. This dissertation analyzes the importance of distributed architectures concerning real-time applications and it also de- scribes some related concepts. In order to evaluate the logical and temporal performance of a communica- tion network, it is necessary to use tools, commonly named as sni®ers, which allow the examination of the tra±c. Although there are a lot of these tools for Ethernet, its development was carried out by the requisites of general purpose data networks. The majority of existing applications can be used on conventional computers (an ordinary network interface card is enough). However, owing to the architecture of computational systems, their multi- programming abilities and to the way time-stamping of messages is done, these applications do not satisfy the speci¯c needs of some real-time proto- cols, namely regarding the resolution and precision to measure the moments of transmission and reception of messages. To answer to these limitations, this dissertation presents a sni®er which is able to respond to the speci¯c needs of real-time protocols. Therefore, the reception, time-stamping and management of messages are done using ded- icated hardware. In this context, programmable logical devices, speci¯cally FPGAs, and synthesizable cores were used, which permitted, in a simple way, the implementation of MAC Ethernet layer by using Xilinx LogicCORE Tri-Mode Ethernet MAC. The remaining modules implemented on FPGA aim the writing of received messages and all associated information in mem- ory for later reading and sending via USB. To intercalate a sni®er within the network in the least intrusive way, a TAP Ethernet, also known as Y- splitter, was built, which permitted the capture in full-duplex connections. This way, information is duplicated to FPGA, then, its time-stamping is done and ¯nally, data is sent to a computer via USB. Information is collected and stored in a ¯le compatible with Wireshark, which allows its utilization and subsequent analysis by using standard/regular tools. Mechanisms that per- mit the treatment of gathered information through calculation tools (which can generate plots and helps to characterize the collected data) were also created. Concerning the obtained results, it is possible to infer that this tool permits meticulous temporal measurements, with a resolution of 10ns and a maxi- mum error of 100ns. On the other hand, some limitations were experienced, particularly regarding transfer via USB, which results in a more limited capture if the capacity of temporary storage of the FPGA runs out. This happens when the transmission rate from Ethernet network is higher than the transfer rate between FPGA and the personal computer. Still, software- based applications can present outcomes with a temporal resolution of 1¹s and an uncertainty of milliseconds. We can also conclude that in certain situations some messages can be lost without the user is being informed about it

Telecommunications for the Needy: How needed are they?

Telecommunications, mobile and non-mobile, play a major role in our society, but their role as tools for escaping poverty remains a policy agenda still with room for progress both in Europe and around the World. Some groups in society, like the needy, have difficulties in accessing and using such technologies in ways that mirror the debates of the late 90s over the "digital divide". For some groups, like the needy, it would be more exact to address the concept of digital poverty rather than digital divide, because without access to telecommunications one might not have the same degree of opportunities to leave poverty or not to fall into poverty [34] [3] [4]. The goal of this paper is to scope the problem by departing from the Portuguese case study. Our research is empirical and highlights the telecommunication ownership and expenditures of the Portuguese population, and specially the most fragile segments within it. Such an effort is undertaken while not ignoring major issues of political economy of the contemporary globalizing networked society. Our main argument in this paper is that, if telecommunications are a needed tool for the lower income segments of the population, that is the needy, a debate around digital poverty associated to mobile telecommunications is needed in Europe too and to address such issues we need public policy commitments.needy, mobile telecommunications, digital poverty, digital divide, telecommunication policies

Multi-antenna GNSS Receiver Tracking Algorithm for Vehicles With Unconstrained Three-dimensional Motion

An algorithm for GNSS GPS/GLONASS receivers is presented that allows the receiver to seamlessly combine the inputs from multiple antennas during signal tracking in order to keep full sky visibility at all times. This algorithm has applications for both aeronautical and space applications in all kinds of vehicles with unconstrained three-dimensional motion capabilities: high maneuverability jet aircraft, rockets, satellites, unmanned aerial vehicles (UAVs), etc. The algorithm presented here keeps track of the received signal-to-noise ratios (SNR) and carrier phase on each of the antennas. For each set of correlation values the receiver selects the input antenna with the best SNR in order to do navigation message decoding and ranging. This fast-switching antenna selection process allows the receiver to stay synchronized with the incoming satellite signal for as long as at least one of the antennas of the set is within line-of-sight of the transmitting satellite. Distributing enough antennas throughout the fuselage of a vehicle, this algorithm will ensure that the receiver does not lose synchronization with the GNSS signals even during threedimensional maneuvers like spins and attitude changes. This algorithm was implemented on a four-antenna GNSS receiver prototype hardware, and tested using a GNSS signal simulator. During these tests the multi-antenna tracking algorithm performed successfully. The results of some of these tests are presented in this paper.Instituto de Investigaciones en Electrónica, Control y Procesamiento de Señale

Conflito armado em Cabo Delgado

Lusíada. Política internacional e segurança. - ISSN 1647-1342. - S. 1, n. 19-20 (2020). - p. 27-65

eGovernment e Digital Divide: ou eGovernment Divide?

É propósito da dissertação examinar as definições dos conceitos eGovernment e Digital Divide e a forma como o debate sobre o conceito de Digital Divide tem vindo a chamar a atenção para diferentes Digital Divides. Em seguida, olharemos para o que o eGovernment implica em relação ao fenómeno do Digital Divide. Quais são as desvantagens e vantagens da administração em linha? Poderá a implementação de serviços de eGovernment significar o surgimento de novas desigualdades em termos de acesso a serviços públicos? Uma série de cenários são considerados, que incluem reflexões sobre a forma como podem surgir diferenças entre países e intra-países. Tentaremos identificar quais os indivíduos que utilizam e os que não utilizam serviços de eGovernment. Através de análise de estatísticas oficiais sobre Portugal e Reino Unido, tentaremos rastrear evidências de novas divisões (Digital Divides) no que respeita ao eGovernment. Iremos também refelectir sobre a evolução da Web 2.0, de modo a mostrar como os governos estão a usar as novas potencialidades da Internet para o desenvolvimento do eGovernment. Sugere-se ainda a necessidade de novas pesquisas que possam mostrar com maior detalhe o relacionamento entre eGovernment e Digital Divide, incluindo uma chamada de atenção para a necessidade de monitorizar o desenvolvimento de novas formas de eGovernment que possam surgir com a evolução da Web 2.0, nomeadamente, no que ao Digital Divide diz respeito.First we will examine definitions of the eGovernment and Digital Divide and the way the debate about the concept is drawing attention to different Digital Divides. Then we will look at what eGovernment entails. What are the disadvantages and advantages of eGovernment? Moreover, does eGovernment actually mean new inequalities in terms of access to public services? A number of scenarios are considered, which include reflections upon how cross-national differences may arise. Next, we try to identify those who use eGovernment services and those who do not. Through secondary analysis of official statistics for, mainly, the UK and Portugal, we will try to trace evidence of new Digital Divides. We will turn also to the evolution of web 2.0, showing how governments are using this as new arena for the development of eGovernment. We suggest also new researches for monitoring the development of web 2.0 eGovernment in relation to Digital Divide concerns

Spanish women athletes’ performance in the Summer Olympic Games history

In this study, an analysis was made of the qualitative and quantitative evolution of the participation and results obtained by the Spanish athletes throughout the Olympic Games, for which their records were compared to those of the men's team from Paris 1900 to Rio 2016. During the study, the growing weight of Spanish women athletes was analysed, resulting in the Women and Sport programme (2007), which seems to have been a determining factor in the improvement of the performance of Spanish women athletes, which surpassed that of the men's team in the last two editions, for the first time in history and in a consecutive manner. The data revealed a growing weight of women, with a historical representation much lower in the Olympic Games (less than 14% until Barcelona 1992) and significantly lower than men from the same (beginning to be more than 30%). This progression has been accompanied by a greater value in the variable weight of the medals, this fact was accentuated in the last editions of London 2012 (65%) and Rio de Janeiro 2016 (60%). It is clear from the results that there is plenty of room for improvement in women's sport. Empowering Spanish female athletes, increasing social and economic recognition, and identifying which are the differential factors that make them more efficient with respect to the male team, can optimize strategies and results in the third sector of sport in Spain

The state of exception as the rule of democratic States

Polis. - ISSN 0872-8208. - S. 2, n. 4 (Julho-Dezembro 2021). - p. 39-55.Este trabalho está direcionado para o estado de exceção a ser aplicado em Estados democráticos na atualidade, captando numa primeira fase a sua evolução e teorias mais relevantes sobre o tema no seu percurso histórico. Absorvendo posteriormente de que forma este mecanismo excecional, que visa proteger em último caso a Constituição de um Estado, acaba por se tornar um possível inimigo a esse mesmo Estado. Analisa-se por isso um mecanismo positivado e crucial na proteção de um Estado de Direito, porém igualmente perigoso, pela problemática em definir nitidamente os limites do seu emprego. Questionando- se até que ponto a atuação governativa mantem-se em conformidade com um Estado democrático e não transgride para um regime totalitário.This work is directed towards the state of exception to be applied in democratic States today, capturing, in a first phase, its evolution and the most relevant theories on the subject in its historical trajectory. Subsequently absorbing how this exceptional mechanism, which ultimately seeks to protect the Constitution of a State, ends up becoming a possible enemy of that same State. Therefore, it is analyzed a positive and crucial mechanism in the protection of a Rule of Law, but equally dangerous, due to the problem of clearly defining the limits of its use. Questioning the extent to which government action remains in conformity with a democratic State and does not transgress towards a totalitarian regime

Mobile communications of the needy and poor: Affordability indicators, European data, social tariffs

This section summarizes the data and information collected across Europe and beyond, inside the COST 605 Action (2008-2011), and can be relevant for separate analysis, research and regulations about the mobile communications costs of poor and needy groups. Miscellaneous social and macro-economic data on the needy and their mobile communications usage in five European countries are presented. It also contains the specification of a new indicator whereby the affordability of mobile communications for poor and needy can be established, and the corresponding results for 7 countries in 2006 and 2010. The indicator is the "poor's purchasing power parity (PPP) in wireless minutes per month", based on reported data collected on the distribution amongst poor and needy groups in Georgia and France. An Appendix gives some data sources for the countries where data were collected

Confiabilidad entre instrumentos (T-Force y Myotest) en la valoración de la fuerza

The purpose of this study was to determine the inter-machine reliability of two devices routinely used to measure variables in sports performance: the linear position measuring device (LPM, isoinertial dynamometer T-Force) and the (AC) 3-D accelerometer (Myotest Sport, S4P model). 40 bench press exercises (25 kg) were analysed at concentric contraction phase and at maximum velocity, carried out by three different subjects (age: 26.74 ± 1.2 years, height: 175.74 ± 4.04 cm, weight: 78.7 ± 3.35 kg). Variables analysed comprised maximum velocity, maximum estimated force and estimated peak power. The data from both devices was collected simultaneously. Three simple lineal regression models were developed, supplied by the linear position measuring device (LPM) on the basis of the accelerometer´s (AC) data. The assumption of independence of errors was compared by means of the Durbin-Watson test. Partial autocorrelation coefficients were calculated for a p<.05 significance level. It has not been possible to confirm the presence of a general correlation between the measurements of both devices. The data was characterised by a generalised autocorrelation and it is recommended that strategies reflecting error control resulting from the data dependence factor be applied when measuring an athlete´s performance. An inter-machine correlation was only found in one of the non conclusive cases: (Peak Power) variable and subject 1, r(10) = .64, p = .024. No partial autocorrelation was found. The AC device obtained higher average and dispersion values than the LPM device. The results show the probability of an increase to the value of uncertainty of the AC device measurements in accordance with Metrology specified guidelines. Both devices should not be used interchangeably when assessing and monitoring training.El estudio pretende caracterizar la confiabilidad entre dos instrumentos, medidor de posicionamiento lineal (MPL, dinamómetro inercial T-Force) y el acelerómetro (AC) 3-D (Myotest Sport, modelo S4P) habituales en la medición de variables de rendimiento. Fueron analizados 40 ensayos en la realización del ejercicio press banca (25 kg) en fase concéntrica a la máxima velocidad por tres sujetos (26.74 ± 1.2 años, 175.74 ± 4.04 cm, 78.7 ± 3.35 kg). Las variables analizadas fueron velocidad máxima, fuerza máxima estimada y pico de potencia estimado. Ambos aparatos obtuvieron los datos simultáneamente. Se desarrollaron tres modelos de regresión lineal simple proporcionados por el medidor de posicionamiento lineal (MPL) a partir de los datos del acelerómetro (AC). Se contrastó el supuesto de independencia de los errores mediante la prueba de Durbin-Watson. Se calcularon autocorrelaciones parciales para un nivel de significación p<.05. No ha sido posible confirmar la existencia general de correlaciones entre las medidas de ambos aparatos. Los datos estuvieron caracterizados por una autocorrelación generalizada y se recomienda la utilización de estrategias que contemplen el control del error producido por el factor de dependencia de los datos cuando se miden deportistas. Sólo se encontró correlación entre aparatos en unos de los casos no concluyentes, variable (Pico de Potencia) y sujeto 1, r(10) = .64, p = .024. No se encontraron autocorrelaciones parciales. AC obtiene mayores valores promedio y de dispersión que MPL. Los resultados evidencian probabilidad de aumento del valor de la incertidumbre de la medida en AC conforme a las orientaciones especificadas en Metrología. Ambos aparatos no deberían usarse indistintamente en la evaluación y control del entrenamiento

Reliability and comparability of the accelerometer and the linear position measuring device in resistance training

The purpose of this study was to determine the intermachine reliability attained from devices used to measure the common variables in sports performance. Repeatability conditions were established by creating a similar set of conditions under which the measurements were taken from both devices. The objectives of this research were to demonstrate the reliability between two devices in a bench press movement—the linear position measuring device (LPM) isoinertial dynamometer (T-Force) and the 3D (Myotest) accelerometer (AC)—and to compare the existing correlations between maximum velocity, maximum estimated strength, and peak power estimate variables in the bench press exercise. Forty bench press exercise trials were analyzed simultaneously, performed by 3 different subjects (age: 26.74 ± 1.2 years, height: 175.74 ± 4.04 cm, weight: 78.7 ± 3.35 kg) at maximum velocity (25 kg additional load). Three simple linear regression models were developed, supplied by the LPM on the basis of the AC data. The assumption of independence of errors was compared by means of the Durban-Watson test, and partial autocorrelation coefficients were established at an overall p < 0.05 significance level. It has not been possible to confirm the presence of a general correlation between the measurements of both devices. Regarding the assumption of independence of errors, the presence of generalized autocorrelation was confirmed. Linear regression analysis revealed an intermachine correlation in one of the nonconclusive cases, (peak power) variable and subject 1, r (10) = 0.640, p = 0.024. No partial autocorrelation was found. The devices should not be used interchangeably as instruments