Acoustic system for ground truth underwater positioning in DEEC's test tank

Desenvolvimento de um sistema acústico de posicionamento capaz de estimar, em tempo real, a posição tridimensional de objetos dentro do tanque de ensaios do DEEC.A obtenção desta posição "ground truth" é fundamental para o apoio a ensaios de sistemas de navegação subaquáticos e para o controlo de veículos robóticos tais como AUV's e ROV's.Development of an acoustic positioning system, capable of estimating, in real time, the three-dimensional position of an object inside the DEEC's test tank. The ability to obtain this ground truth position is fundamental to support tests of underwater navigation systems, and to the control of robotic vehicles such as AUV's and ROV's

Real100G.COM

In 2012 a group of researchers proposed a basic research initiative to the German Research Foundation (DFG) as a special priority project (SPP) with the name: Wireless 100 Gbps and beyond. The main goal of this initiative was the investigation of architectures, technologies and methods to go well beyond the state of the art. The target of 100 Gbps was set far away from the (at that time) achievable 1 Gbps such that it was not possible to achieve promising results just by tuning some parameters. We wanted to find breakthrough solutions. When we started the work on the proposal we discussed the challenges to be addressed in order to advancing the wireless communication speed significantly. Having the fundamental Shannon boundary in mind we discussed how to achieve the 100 Gbps speed.Angesichts der rapiden Entwicklung der Funkkommunikation hat die Deutsche Forschungsgemeinschaft im Jahr 2012 ein Schwerpunktprogramm mit dem Titel "Wireless 100 Gbps and beyound" (dt.: Drahtloskommunikation mit 100 Gbps und mehr) gestartet. Diese Initiative zielte auf neue Lösungen, Methoden und neues Wissen zur Lösung des Problems des kontinuierlichen Bedarfs an immer höheren Datenraten im Bereich der Funkkommunikation. Eine international besetze Jury hat etliche Projektvorschläge evaluiert, aus denen 11 Projekte ausgewählt und über zweimal 3 Jahre von Mitte 2013 bis Mitte 2019 gefördert wurden. Das vorliegende Buch versammelt die Ansätze, Architekturen und Erkenntnisse der Projekte. Es überspannt einen breiten Themenbereich, angefangen mit speziellen Fragen der physikalischen Übertragung, des Antennendesigns und der HF-Eingangs-Architekturen für unterschiedliche Frequenzbereiche bis 240 GHz. Darüber hinaus beschreibt das Buch Ansätze für Ultra-Hochgeschwindigkeits-Funksysteme, deren Basisbandverarbeitung, Kodierung sowie mögliche Umsetzungen. Nicht zuletzt wurden auch Fragen des Protokolldesigns behandelt, um eine enge Integration in moderne Computersysteme zu erleichtern

Measuring Time-of-Flight in an Ultrasonic LPS System Using Generalized Cross-Correlation

In this article, a time-of-flight detection technique in the frequency domain is described for an ultrasonic Local Positioning System (LPS) based on encoded beacons. Beacon transmissions have been synchronized and become simultaneous by means of the DS-CDMA (Direct-Sequence Code Division Multiple Access) technique. Every beacon has been associated to a 255-bit Kasami code. The detection of signal arrival instant at the receiver, from which the distance to each beacon can be obtained, is based on the application of the Generalized Cross-Correlation (GCC), by using the cross-spectral density between the received signal and the sequence to be detected. Prior filtering to enhance the frequency components around the carrier frequency (40 kHz) has improved estimations when obtaining the correlation function maximum, which implies an improvement in distance measurement precision. Positioning has been achieved by using hyperbolic trilateration, based on the Time Differences of Arrival (TDOA) between a reference beacon and the others

Improving Time of Arrival Estimation Using Encoded Acoustic Signals

Underwater localization systems are crucial to explore the sea. The most common systems for this environment use acoustic signals for position estimation and communication.There are several challenges that these systems have to tackle when using underwater acoustic signals. This dissertation will solely focus on the part of these systems that estimates the exact moment an acoustic signal has arrived, this is crucial, to establish an exact relative position.It is proposed the use of pseudorandom binary sequences modulated in BPSK. Such sequences have extremely low cross-correlation and high autocorrelation. Using this property, we hope that the correlation peak will render the exact moment a signal arrives.Also, given that it is possible to generate a set of orthogonal pseudorandom binary sequences, 16 of these sequences were generated and a symbol of 4 bits was assigned to each one of them. This way, the sequence being received can be identified and some data transmitted

Efficient complementary sequences-based architectures and their application to ranging measurements

Premio Extraordinario de Doctorado de la UAH en 2015En las últimas décadas, los sistemas de medición de distancias se han beneficiado de los avances en el área de las comunicaciones inalámbricas. En los sistemas basados en CDMA (Code-Division Multiple-Access), las propiedades de correlación de las secuencias empleadas juegan un papel fundamental en el desarrollo de dispositivos de medición de altas prestaciones. Debido a las sumas ideales de correlaciones aperiódicas, los conjuntos de secuencias complementarias, CSS (Complementary Sets of Sequences), son ampliamente utilizados en sistemas CDMA. En ellos, es deseable el uso de arquitecturas eficientes que permitan generar y correlar CSS del mayor número de secuencias y longitudes posibles. Por el término eficiente se hace referencia a aquellas arquitecturas que requieren menos operaciones por muestra de entrada que con una arquitectura directa. Esta tesis contribuye al desarrollo de arquitecturas eficientes de generación/correlación de CSS y derivadas, como son las secuencias LS (Loosely Synchronized) y GPC (Generalized Pairwise Complementary), que permitan aumentar el número de longitudes y/o de secuencias disponibles. Las contribuciones de la tesis pueden dividirse en dos bloques: En primer lugar, las arquitecturas eficientes de generación/correlación para CSS binarios, derivadas en trabajos previos, son generalizadas al alfabeto multinivel (secuencias con valores reales) mediante el uso de matrices de Hadamard multinivel. Este planteamiento tiene dos ventajas: por un lado el aumento del número de longitudes que pueden generarse/correlarse y la eliminación de las limitaciones de las arquitecturas previas en el número de secuencias en el conjunto. Por otro lado, bajo ciertas condiciones, los parámetros de las arquitecturas generalizadas pueden ajustarse para generar/correlar eficientemente CSS binarios de mayor número de longitudes que con las arquitecturas eficientes previas. En segundo lugar, las arquitecturas propuestas son usadas para el desarrollo de nuevos algoritmos de generación/correlación de secuencias derivadas de CSS que reducen el número de operaciones por muestra de entrada. Finalmente, se presenta la aplicación de las secuencias estudiadas en un nuevo sistema de posicionamiento local basado en Ultra-Wideband y en un sistema de posicionamiento local basado en ultrasonidos

Correlator implementation for orthogonal CSS used in an ultrasonic LPS

This paper presents a new architecture for the correlation of orthogonal complementary sets of sequences (OCSS) and their performance in an ultrasonic local positioning system (U-LPS). OCSS are sets of sequences whose addition of correlation functions has ideal properties, that makes interference-free code-division multiple access (CDMA) possible. They can be used to encode the signals emitted by a CDMA based U-LPS, enhancing the performance of such systems in terms of immunity against noise, multipath propagation, and near-far effect. Also, the orthogonality of the codes offers an operation resistance to multiaccess interference, which endows the U-LPS with the capability of simultaneous emission from different beacons. On the other hand, the detection of OCSS codes can be performed by means of efficient algorithms. This paper presents an optimization of previous proposals allowing the simultaneous correlation of OCSS by using fewer operations and memory elements. Furthermore, the hardware implementation of the proposed optimization is also addressed, and an U-LPS based on this proposal is presented.Fil: Peréz Rubio, M. Carmen. Universidad de Alcalá; EspañaFil: Sanz Serrano, Rebeca. Universidad de Alcalá; EspañaFil: Ureña Ureña, Jesús. Universidad de Alcalá; EspañaFil: Hernández Alonso, Álvaro. Universidad de Alcalá; EspañaFil: de Marziani, Carlos Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Álvarez Franco, Fernando J.. Universidad Nacional de la Patagonia "San Juan Bosco". Facultad de Ingeniería - Sede Comodoro; Argentin

Sistema de comunicação por luz visível baseado em FPGA

Mestrado em Engenharia Electrónica e TelecomunicaçõesO crescente desenvolvimento da indústria electrónica veio acelerar as potencialidades de variadíssimos dispositivos de comunicação. A comunicação hoje em dia é de fácil acesso para qualquer pessoa, onde quer que esteja. Em situações desfavoráveis exige-se que o sistema de comunicação tenha a capacidade de atenuar as interferências que corrompem o sinal de informação desejado. Vários sistemas de comunicação e dispositivos sofisticados têm sido desenvolvidos com intuito de salvaguardar as pretensões e os anseios à medida que os nossos hábitos e necessidades se tornam mais exigentes alterando. Apesar de ter surgido no auge da segunda guerra mundial o sucesso de técnica por espalhamento de espectro (Spread Spectrum) só ficou comprovado há cerca de duas décadas por falta de tecnologias avançadas. O espalhamento de espectro é uma das técnicas de modulação de sinal de transmissão com propriedades que não se encontram em nenhuma outra técnica de modulação. Um dos objectivos desta dissertação é desenvolver um sistema de comunicação spread spectrum por meio de luz visível. A disseminação dos bits de dados foi feita recorrendo uma das duas principais técnicas de espalhamento de espectro: o espalhamento por sequência directa (Direct Sequence Spread Spectrum, DSSS), usando a sequência de Barker modificada de comprimento 10. Todo o sistema de comunicação foi desenvolvido em software MATLAB utilizando a ferramenta de suporte System Generator da Xilinx para posterior lançamento numa plataforma FPGA. Arquitectura do receptor usa um conversor analógico digital de 14 bits de resolução e um Matched Filter para uma rápida sincronização e aquisição de dados.The increasing development, of the electronics industry the potential for a variety of different communication devices has accelerated. Communications today are easily accessible to anyone, wherever one is. Under unfavorable situations the communication system must have the ability to mitigate interference that corrupts the desired information in the signal. Several communication systems and sophisticated devices, have been developed with a view to safeguard the aspirations and desires as our habits and needs are changing. Although originated at the height of the second world war the success of spread spectrum technology has only been demonstrated about two decades ago due to the lack of advanced technologies. Spread spectrum is a modulation technique for signal transmission with unique properties not found in any other modulation technique. One of the objectives of this dissertation is the development and implementation of a spread spectrum communication system using visible light. The spread of the data bits was done using one of two main spread spectrum techniques - Direct Sequence Spread Spectrum (DSSS) - using a modified Barker sequence of length 10. The entire communication system was developed using the MATLAB software tool to support the Xilinx System Generator for later release on a platform FPGA. The receiver architecture uses 14-bit analog to digital converter resolution and a Matched Filter for a quick data synchronization and acquisition

Analog Network Coding for Multi-User Spread-Spectrum Communication Systems

This work presents another look at an analog network coding scheme for multi-user spread-spectrum communication systems. Our proposed system combines coding and cooperation between a relay and users to boost the throughput and to exploit interference. To this end, each pair of users, $\mathcal{A}$ and $\mathcal{B}$, that communicate with each other via a relay $\mathcal{R}$ shares the same spreading code. The relay has two roles, it synchronizes network transmissions and it broadcasts the combined signals received from users. From user $\mathcal{B}$'s point of view, the signal is decoded, and then, the data transmitted by user $\mathcal{A}$ is recovered by subtracting user $\mathcal{B}$'s own data. We derive the analytical performance of this system for an additive white Gaussian noise channel with the presence of multi-user interference, and we confirm its accuracy by simulation.Comment: 6 pages, 2 figures, to appear at IEEE WCNC'1

Implementación en Hardware Configurable de un Correlador Eficiente de Secuencias GPC

Este trabajo de fin de grado consiste en la implementación en hardware reconfigurable (FPGA, Field Programmable Gate Array) de un correlador eficiente de secuencias GPC (General Pairwise Complementary), basado en dos parejas Golay incorreladas. El proyecto ha sido diseñado con la herramienta software Vivado haciendo uso del lenguaje de programación VHDL con estudio previo de la algoritmia en la plataforma Matlab. Este tipo de codificación presenta unas buenas características de correlación aperiódica con zonas de correlación cero alrededor del pico principal. Además, una de las mayores ventajas de las secuencias GPC es la posibilidad de implementar modelos eficientes reduciendo el número de operaciones requeridas para su detección, frente a un correlador directo convencional.This project consists in the implementation in reconfigurable hardware (FPGA, Field Programmable Gate Array) of an efficient Correlator for Generalized Pairwise Complementary (GPC) sequences, which are based on uncorrelated Golay pairs. The design has been carried out with Vivado software and programmed in VHDL, having made previous studies with the mathematic tool, Matlab. This type of codification presents remarkable aperiodic correlation characteristics in comparison with other family codes. Moreover, one of the main advantages of GPC sequences is the possibility of implementing efficient models, reducing the number of required operations in comparison with those required by a direct correlator.Grado en Ingeniería en Electrónica y Automática Industria