17 resultados para digital communications

em Universidad Politécnica de Madrid


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La señalización digital o digital signage es una tecnología de comunicaciones digital que se está usando en los últimos años para reemplazar a la antigua publicidad impresa. Esta tecnología mejora la presentación y promoción de los productos anunciados, así como facilita el intercambio de información gracias a su colocación en lugares públicos o al aire libre. Las aplicaciones con las que cuenta este nuevo método de publicidad son muy variadas, ya que pueden variar desde ambientes privados en empresas, hasta lugares públicos como centros comerciales. Aunque la primera y principal utilidad de la señalización digital es la publicidad para que el usuario sienta una necesidad de adquirir productos, también la posibilidad de ofrecer más información sobre determinados artículos a través de las nuevas tecnologías es muy importante en este campo. La aplicación realizada en este proyecto es el desarrollo de un programa en Adobe Flash a través de lenguaje de programación XML. A través de una pantalla táctil, el usuario de un museo puede interactivamente acceder a un menú en el que aparecen los diferentes estilos de arte en un determinado tiempo de la historia. A través de una línea de tiempo se puede acceder a información sobre cada objeto que esté expuesto en la exhibición. Además se pueden observar imágenes de los detalles más importantes del objeto que no pueden ser vistos a simple vista, ya que no está permitido manipularlos. El empleo de la pantalla interactiva sirve para el usuario de la exhibición como una herramienta extra para recabar información sobre lo que está viendo, a través de una tecnología nueva y fácil de usar para todo el mundo, ya que solo se necesita usar las propias manos. La facilidad de manejo en aplicaciones como estas es muy importante, ya que el usuario final puede no tener conocimientos tecnológicos por lo que la información debe darse claramente. Como conclusión, se puede decir que digital signage es un mercado que está en expansión y que las empresas deben invertir en el desarrollo de contenidos, ya que las tecnologías avanzan aunque el digital signage no lo haga, y este sector podría ser muy útil en un futuro no muy lejano, ya que la información que es capaz de transmitir al espectador en todos los lugares es mucho más válida y útil que la proporcionada por un simple póster impreso en una valla publicitaria. Abstract The Digital signage is a digital communications technology being used in recent years to replace the old advertising printed. This technology improves the presentation and promotion of the advertised products, and makes easy the exchange of information with its placement in public places or outdoors. The applications that account this new method of advertising are several; they can range from private rooms in companies, to public places like malls. Although the first major utility of Digital signage is the advertising that makes the user feel and need of purchasing products. In addition, the chance of providing more information about certain items through new technologies is very important in this field. The application made in this project is the development of a program in Adobe Flash via XML programming language. Through a touch-screen, a museum user can interactively access a menu in which different styles of art in a particular time in history appears. Through a timeline you can access to information about each object that is exposed on display. Also you can see pictures of the most important details of the object that can not be seen with the naked eye, since it is not allowed to manipulate it. The use of the interactive screen serves to the user exhibition as an extra tool to gather information about what is seeing through a new technology and easy to use for everyone, since only need to use one’s own hands. The ease of handling in applications such as this is very important as the end user may not have expertise technology so the information should be clearly. As conclusion, one can say digital signage is an expansion market and companies must invest in content development, as although digital technologies advance digital signage does not, and this sector could be very useful in a near future, because information that is able of transmitting the everywhere viewer is much more valid and useful than that provided by a simple printed poster on a billboard.

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This paper describes an ADS-B implementation in air-to-air and ground based experimental surveillance within a prototype ATM system. The relations between airborne and ground systems related to surveillance are detailed, and the prototype surveillance systems and their algorithms described. Their performance is analysed, based both on simulated and real data.

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This work presents a method to estimate and correct slow time-dependent position errors due to non perfect ground station synchronization and tropospheric propagation. It uses opportunity traffic emissions, i.e. signals transmitted from the aircrafts within the coverage zone. This method is used to overcome the difficulty of installing reference beacons simultaneously visible by all the base stations in a given Wide Area Multilateration (WAM) system.

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En la actualidad, los avances en la ciencia de la esteganografía lingüística en español abren nuevas líneas de investigación en su aplicación a la protección / privacidad de las comunicaciones digitales y en el marcado de textos. El presente artículo profundiza en el interés del uso de la reordenación de complementos del verbo en textos existentes en lengua española con utilidad en esteganografía lingüística y en el marcado digital de textos (marca de agua). Abstract. At present the advances in the science of linguistic steganography in Spanish open new lines of research in its application for the protection / privacy of digital communications and in the marking of texts. This article studies the possible interest of reordering complements of the verb in existing texts in Spanish language with regard to its usefulness in linguistic steganography and in digital marking of texts (watermarks).

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Many problems in digital communications involve wideband radio signals. As the most recent example, the impressive advances in Cognitive Radio systems make even more necessary the development of sampling schemes for wideband radio signals with spectral holes. This is equivalent to considering a sparse multiband signal in the framework of Compressive Sampling theory. Starting from previous results on multicoset sampling and recent advances in compressive sampling, we analyze the matrix involved in the corresponding reconstruction equation and define a new method for the design of universal multicoset codes, that is, codes guaranteeing perfect reconstruction of the sparse multiband signal.

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Desde que las Tecnologías de la Información y la Comunicación comenzaron a adquirir una gran importancia en la sociedad, uno de los principales objetivos ha sido conseguir que la información transmitida llegue en perfectas condiciones al receptor. Por este motivo, se hace necesario el desarrollo de nuevos sistemas de comunicación digital capaces de ofrecer una transmisión segura y fiable. Con el paso de los años, se han ido mejorando las características de los mismos, lo que significa importantes avances en la vida cotidiana. En este contexto, uno de los sistemas que más éxito ha tenido es la Modulación Reticulada con Codificación TCM, que aporta grandes ventajas en la comunicación digital, especialmente en los sistemas de banda estrecha. Este tipo de código de protección contra errores, basado en la codificación convolucional, se caracteriza por realizar la modulación y codificación en una sola función. Como consecuencia, se obtiene una mayor velocidad de transmisión de datos sin necesidad de incrementar el ancho de banda, a costa de pasar a una constelación superior. Con este Proyecto Fin de Grado se quiere analizar el comportamiento de la modulación TCM y cuáles son las ventajas que ofrece frente a otros sistemas similares. Se propone realizar cuatro simulaciones, que permitan visualizar diversas gráficas en las que se relacione la probabilidad de bit erróneo BER y la relación señal a ruido SNR. Además, con estas gráficas se puede determinar la ganancia que se obtiene con respecto a la probabilidad de bit erróneo teórica. Estos sistemas pasan de una modulación QPSK a una 8PSK o de una 8PSK a una 16QAM. Finalmente, se desarrolla un entorno gráfico de Matlab con el fin de proporcionar un sencillo manejo al usuario y una mayor interactividad. ABSTRACT. Since Information and Communication Technologies began to gain importance on society, one of the main objectives has been to achieve the transmitted information reaches the receiver perfectly. For this reason, it is necessary to develop new digital communication systems with the ability to offer a secure and reliable transmission. The systems characteristics have improved over the past years, what it means important progress in everyday life. In this context, one of the most successful systems is Trellis Coded Modulation TCM, that brings great advantages in terms of digital communications, especially narrowband systems. This kind of error correcting code, based on convolutional coding, is characterized by codifying and modulating at the same time. As a result, a higher data transmission speed is achieved without increasing bandwidth at the expense of using a superior modulation. The aim of this project is to analyze the TCM performance and the advantages it offers in comparison with other similar systems. Four simulations are proposed, that allows to display several graphics that show how the Bit Error Ratio BER and Signal Noise Ratio SNR are related. Furthermore, it is possible to calculate the coding gain. Finally, a Matlab graphic environment is designed in order to guarantee the interactivity with the final user.

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The award of the digital dividend can consolidate auctions as the preferred mechanism for spectrum allocation. Knowing in advance an estimate of what the results of an auction with these characteristics could be would be unquestionably useful for those in charge of designing the process, even if at the end another method such as a beauty contest is chosen. This article provides a simulation of a digital dividend auction in a major-type European country. In one of the scenarios, the spectrum is not pre-allocated to any service in particular (service neutrality) while in the remaining four, blocks of spectrum are pre-allocated to DTT, mobile multimedia and mobile broadband communications. The results of the simulations reveal that the service neutrality scenario maximizes revenues for the seller and that, in general, DTT operators would seem to have fewer opportunities as the spectrum packaging is less protective for them.

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A new method to obtain digital chaos synchronization between two systems is reported. It is based on the use of Optically Programmable Logic Cells as chaos generators. When these cells are feedbacked, periodic and chaotic behaviours are obtained. They depend on the ratio between internal and external delay times. Chaos synchronization is obtained if a common driving signal feeds both systems. A control to impose the same boundary conditions to both systems is added to the emitter. New techniques to analyse digital chaos are presented. The main application of these structures is to obtain secure communications in optical networks.

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In this paper an approach to the synchronization of chaotic circuits has been reported. It is based on an optically programmable logic cell and the signals involved are fully digital. It is based on the reception of the same input signal on sender and receiver and from this approach, with a posterior correlation between both outputs, an identical chaotic output is obtained in both systems. No conversion from analog to digital signals is needed. The model here presented is based on a computer simulation.

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Digital chaotic behavior in an optically processing element is reported. It is obtained as the result of processing two fixed train of bits. The process is performed with an Optically Programmable Logic Gate. Possible outputs for some specific conditions of the circuit are given. These outputs have some fractal characteristics, when input variations are considered. Digital chaotic behavior is obtained by using a feedback configuration. A random-like bit generator is presented.

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Protecting signals is one of the main tasks in information transmission. A large number of different methods have been employed since many centuries ago. Most of them have been based on the use of certain signal added to the original one. When the composed signal is received, if the added signal is known, the initial information may be obtained. The main problem is the type of masking signal employed. One possibility is the use of chaotic signals, but they have a first strong limitation: the need to synchronize emitter and receiver. Optical communications systems, based on chaotic signals, have been proposed in a large number of papers. Moreover, because most of the communication systems are digital and conventional chaos generators are analogue, a conversion analogue-digital is needed. In this paper we will report a new system where the digital chaos is obtained from an optically programmable logic structure. This structure has been employed by the authors in optical computing and some previous results in chaotic signals have been reported. The main advantage of this new system is that an analogue-digital conversion is not needed. Previous works by the authors employed Self-Electrooptical Effect Devices but in this case more conventional structures, as semiconductor laser amplifiers, have been employed. The way to analyze the characteristics of digital chaotic signals will be reported as well as the method to synchronize the chaos generators located in the emitter and in the receiver.

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The type of signals obtained has conditioned chaos analysis tools. Almost in every case, they have analogue characteristics. But in certain cases, a chaotic digital signal is obtained and theses signals need a different approach than conventional analogue ones. The main objective of this paper will be to present some possible approaches to the study of this signals and how information about their characteristics may be obtained in the more straightforward possible way. We have obtained digital chaotic signals from an Optical Logic Cell with some feedback between output and one of the possible control gates. This chaos has been reported in several papers and its characteristics have been employed as a possible method to secure communications and as a way to encryption. In both cases, the influence of some perturbation in the transmission medium gave problems both for the synchronization of chaotic generators at emitter and receiver and for the recovering of information data. A proposed way to analyze the presence of some perturbation is to study the noise contents of transmitted signal and to implement a way to eliminate it. In our present case, the digital signal will be converted to a multilevel one by grouping bits in packets of 8 bits and applying conventional methods of time-frequency analysis to them. The results give information about the change in signals characteristics and hence some information about the noise or perturbations present. Equivalent representations to the phase and to the Feigenbaum diagrams for digital signals are employed in this case.

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A new proposal to have secure communications in a system is reported. The basis is the use of a synchronized digital chaotic systems, sending the information signal added to an initial chaos. The received signal is analyzed by another chaos generator located at the receiver and, by a logic boolean function of the chaotic and the received signals, the original information is recovered. One of the most important facts of this system is that the bandwidth needed by the system remain the same with and without chaos.

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El Hogar Digital Accesible (HDA) de la ETSIST nace con el propósito de acercar las nuevas Tecnologías de la Información a las personas que precisan de necesidades concretas de accesibilidad y usabilidad, dotándoles de herramientas que les permitan aumentar su calidad de vida, confort, seguridad y autonomía. El entorno del HDA consta de elementos de control para puertas, persianas, iluminación, agua o gas, sensores de temperatura, incendios, gas, sistemas de climatización, sistemas de entretenimiento y sistemas de seguridad tales como detectores de presencia y alarmas. Todo ello apoyado sobre una arquitectura de red que proporciona una pasarela residencial y un acceso a banda ancha. El objetivo principal de este PFG ha sido el desarrollo de un sistema de autenticación para el Hogar Digital Accesible de bajo coste. La idea de integrar un sistema de autenticación en el HDA, surge de la necesidad de proteger de accesos no deseados determinados servicios disponibles dentro de un ámbito privado. Algunos de estos servicios pueden ser tales como el acceso a la lectura de los mensajes disponibles en el contestador automático, el uso de equipos multimedia, la desconexión de alarmas de seguridad o simplemente la configuración de ambientes según el usuario que esté autenticado (intensidad de luz, temperatura de la sala, etc.). En el desarrollo han primado los principios de accesibilidad, usabilidad y seguridad necesarios para la creación de un entorno no invasivo, que permitiera acreditar la identidad del usuario frente al sistema HDA. Se ha planteado como posible solución, un sistema basado en el reconocimiento de un trazo realizado por el usuario. Este trazo se usará como clave de cara a validar a los usuarios. El usuario deberá repetir el trazado que registró en el sistema para autenticarse. Durante la ejecución del presente PFG, se justificará la elección de este mecanismo de autenticación frente a otras alternativas disponibles en el mercado. Para probar la aplicación, se ha podido contar con dos periféricos de distintas gamas, el uDraw creado para la PS3 que se compone de una tableta digitalizadora y un lápiz que permite recoger los trazos realizados por el usuario de forma inalámbrica y la tableta digitalizadora Bamboo de Wacom. La herramienta desarrollada permite a su vez, la posibilidad de ser usada por otro tipo de dispositivos como es el caso del reloj con acelerómetro de 3 ejes de Texas Instruments Chronos eZ430 capaz de trasladar los movimientos del usuario al puntero de un ratón. El PFG se encuentra dividido en tres grandes bloques de flujo de trabajo. El primero se centra en el análisis del sistema y las tecnologías que lo componen, incluyendo los distintos algoritmos disponibles para realizar la autenticación basada en reconocimiento de patrones aplicados a imágenes que mejor se adaptan a las necesidades del usuario. En el segundo bloque se recoge una versión de prueba basada en el análisis y el diseño UML realizado previamente, sobre la que se efectuaron pruebas de concepto y se comprobó la viabilidad del proyecto. El último bloque incluye la verificación y validación del sistema mediante pruebas que certifican que se han alcanzado los niveles de calidad necesarios para la consecución de los objetivos planteados, generando finalmente la documentación necesaria. Como resultado del trabajo realizado, se ha obtenido un sistema que plantea una arquitectura fácilmente ampliable lograda a través del uso de técnicas como la introspección, que permiten separar la lógica de la capa de negocio del código que la implementa, pudiendo de forma simple e intuitiva sustituir código mediante ficheros de configuración, lo que hace que el sistema sea flexible y escalable. Tras la realización del PFG, se puede concluir que el producto final obtenido ha respondido de forma satisfactoria alcanzando los niveles de calidad requeridos, siendo capaz de proporcionar un sistema de autenticación alternativo a los convencionales, manteniendo unas cotas de seguridad elevadas y haciendo de la accesibilidad y el precio sus características más reseñables. ABSTRACT. Accessible Digital Home (HDA) of the ETSIST was created with the aim of bringing the latest information and communications technologies closer to the people who has special needs of accessibility and usability increasing their quality of life, comfort, security and autonomy. The HDA environment has different control elements for doors, blinds, lighting, water or gas, temperature sensors, fire protection systems, gas flashover, air conditioning systems, entertainments systems and security systems such as intruders detectors and alarms. Everything supported by an architecture net which provides a broadband residential services gateway. The main goal of this PFG was the development of a low-cost authentication system for the Accessible Digital Home. The idea of integrating an authentication system on the HDA, stems from the need to safeguard certain private key network resources from unauthorized access. Some of said resources are the access to the answering machine messages, the use of multimedia devices, the alarms deactivation or the parameter settings for each environment as programmed by the authenticated user (light intensity, room temperature, etc.). During the development priority was given to concepts like accessibility, usability and security. All of them necessary to create a non invasive environment that allows the users to certify their identity. A system based on stroke pattern recognition, was considered as a possible solution. This stroke is used as a key to validate users. The user must repeat the stroke that was saved on the system to validate access. The selection of this authentication mechanism among the others available options will be justified during this PFG. Two peripherals with different ranges were used to test the application. One of them was uDraw design for the PS3. It is wireless and is formed by a pen and a drawing tablet that allow us to register the different strokes drawn by the user. The other one was the Wacom Bamboo tablet, that supports the same functionality but with better accuracy. The developed tool allows another kind of peripherals like the 3-axes accelerometer digital wristwatch Texas Instruments Chronos eZ430 capable of transfering user movements to the mouse cursor. The PFG is divided by three big blocks that represent different workflows. The first block is focused on the system analysis and the technologies related to it, including algorithms for image pattern recognition that fits the user's needs. The second block describes how the beta version was developed based on the UML analysis and design previously done. It was tested and the viability of the project was verified. The last block contains the system verification and validation. These processes certify that the requirements have been fulfilled as well as the quality levels needed to reach the planned goals. Finally all the documentation has been produced. As a result of the work, an expandable system has been created, due to the introspection that provides the opportunity to separate the business logic from the code that implements it. With this technique, the code could be replaced throughout configuration files which makes the system flexible and highly scalable. Once the PFG has finished, it must therefore be concluded that the final product has been a success and high levels of quality have been achieved. This authentication tool gives us a low-cost alternative to the conventional ones. The new authentication system remains security levels reasonably high giving particular emphasis to the accessibility and the price.

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A possible approach to the synchronization of chaotic circuits is reported. It is based on an Optically Programmable Logic Cell and as a consequence its output is digital, its application to cryptography in Optical Communications comes directly from its properties. The model here presented is based on a computer simulation.