The aim of this thesis was automatic pitch detection in melodic guitar lines and subsequent transcription to guitar tablature. Final system uses comb filtering to detect pitch. Individual notes are separated by beat detection. An algorithm for transcription of notes to guitar tablature, based on minimalization of hand movement is proposed.

The paper deals with analysis of the problems of digital signal processing and with design of the control unit for DSP and audio signal distribution to active external loudspeakers. It describes function of delta-sigma AD converters, the most widely used digital filters and Fast Fourier Transform. The processed signal will be send to external loudspeakers using an Ethernet interface. The paper also covers the design of signal processing unit's hardware and software. Achieved functions and parameters of the unit are discussed in conclusion.

The gradual deterioration and failure of old buildings, bridges and other civil engineering structures invoked the need for Structural Health Monitoring (SHM) systems to develop a means to monitor the health of structures. Dozens of sensing, processing and monitoring mechanisms have been implemented and widely deployed with wired sensors. Wireless sensor networks (WSNs), on the other hand, are networks of large numbers of low cost wireless sensor nodes that communicate through a wireless media. The complexity nature and high cost demand of the highly used wired traditional SHM systems have posed the need for replacement with WSNs. However, the major fact that wireless sensor nodes have memory and power supply limitations has been an issue and many efficient options have been proposed to solve this problem and preserve the long life of the network. This is the reason why data processing algorithms in WSNs focus mainly on the accomplishment of efficient utilization of these scarce resources. In this thesis, we design a low-power and memory efficient data processing algorithm using in-place radix-2 integer Fast Fourier Transform (FFT). This algorithm requires inputs with integer values; hence, increases the memory efficiency by more than 40% and highly saves processor power consumption over the traditional floating-point implementation. A standard-deviation-based peak picking algorithm is next applied to measure the natural frequency of the structure. The algorithms together with Contiki, a lightweight open source operating system for networked embedded systems, are loaded on Z1 Zolertia sensor node. Analogue Device’s ADXL345 digital accelerometer on board is used to collect vibration data. The bridge model used to test the target algorithm is a simply supported beam in the lab.

[ES] Esta tesis explora en profundidad la viabilidad técnica y las prestaciones de un sistema de transmisión para comunicaciones ópticas, de bajo coste y alta velocidad, basado en la multiplexación por división de frecuencia ortogonal (OFDM) mediante la implementación de los algoritmos de procesamiento digital de la señal en tiempo real sobre dispositivos de lógica programable (FPGA). Los sistemas de transmisión de modulación de intensidad y detección directa (IM/DD) parecen ser la solución más interesante para las redes ópticas pasivas (PONs) de bajo coste que serán necesarias para responder a la gran demanda de tráfico de los próximos años, producto del aumento significativo de dispositivos conectados a internet, servicios y programas en la nube, vídeo de alta definición, entre otros. Por tanto, esta tesis tiene como objetivo principal obtener la máxima tasa binaria y eficiencia espectral posible de un sistema IM/DD OFDM en PON (de una sola banda y una sola longitud de onda). Con esta finalidad se ha desarrollado la arquitectura hardware de un receptor OFDM de alta velocidad que opera en tiempo real en un dispositivo FPGA Virtex-7 a una frecuencia de reloj de 312,5 MHz utilizando un conversor analógico digital con una tasa de muestreo de 5 GS/s. Para lograr las mejores prestaciones posibles, se ha intentado aprovechar al máximo el ancho de banda del sistema (acercándose al límite de Nyquist) y se ha realizado una carga variable de las subportadoras del símbolo OFDM atendiendo a las características del canal electro-óptico. Además, se han diseñado e implementado los algoritmos de procesamiento necesarios para la detección y demodulación de los símbolos OFDM, y se ha desarrollado una plataforma experimental que ha permitido validarlos en tiempo real a través de un enlace de fibra monomodo estándar (SSMF). El principal resultado de esta tesis es el haber demostrado experimentalmente que con el sistema propuesto se puede alcanzar una tasa binaria de 19,63 Gb/s y una eficiencia espectral de 8,07 bit/s/Hz sobre 20 km de SSMF, lo cual implica casi duplicar las mejores prestaciones publicadas hasta la fecha. Para completar el diseño del receptor, se ha desarrollado un algoritmo de sincronización de tiempo basado en la correlación cruzada entre un preámbulo conocido y la señal OFDM recibida, el cual presenta una tasa de error extremadamente baja, aun en condiciones de muy baja SNR, y su diseño optimizado requiere menos recursos que otros sincronizadores publicados hasta la fecha. También se ha desarrollado un procesador de FFT de longitud variable mediante una arquitectura paralela segmentada que permite alcanzar hasta una tasa de 10 GS/s en dispositivos Virtex-7 con una eficiencia (área/velocidad) superior a la de otros trabajos publicados, y un ecualizador de canal basado en una técnica de estimación y compensación en frecuencia, que utiliza un preámbulo característico para poder disminuir la complejidad hardware y aumentar la precisión de la estimación. Todos los algoritmos implementados en esta tesis doctoral han sido diseñados para procesar 16 muestras en paralelo, y así poder reducir la frecuencia de reloj (5 GHz/16) hasta valores aceptables para los dispositivos FPGA. / [CA] Aquesta tesi explora en profunditat la viabilitat tècnica i les prestacions d'un sistema de transmissió per a comunicacions òptiques, de baix cost i alta velocitat, basat en la multiplexació per divisió en freqüència ortogonal (OFDM) mitjançant la implementació d'algorismes de processat digital del senyal en temps real sobre dispositius de lògica programable (FPGA). Els sistemes de transmissió de modulació d'intensitat i detecció directa (IM/DD) semblen ser la solució més interesant per a les xarxes òptiques passives (PON) de baix cost que seran necessàries per respondre a la gran demanda de tràfic dels propers anys, producte de l'augment significatiu de dispositius connectats a Internet, serveis i programari al núvol, vídeo d'alta definició, entre d'altres. Per tant, aquesta tesi té com objectiu principal obtenir la màxima taxa binaria i eficiència espectral possible d'un sistema IM/DD OFDM en PON (amb una sola banda i una sola longitud d'ona). Amb aquesta finalitat s'ha desenvolupat l'arquitectura hardware d'un receptor OFDM d'alta velocitat que treballa en temps real a un dispositiu FPGA Virtex-7 amb una freqüència de rellotge de 312,5 MHz utilitzant un convertidor analògic a digital amb una taxa de mostreig de 5 GS/s. Per aconseguir les millors prestacions possibles, s'ha intentat aprofitar al màxim l'ample de banda del sistema (aproximant-se al límit de Nyquist) i s'ha realitzat una càrrega variable de les subportadores del símbol OFDM atenent a les característiques del canal electró-òptic. A més, s'han dissenyat e implementat els algorismes de processament necessaris per la detecció i desmodulació dels símbols OFDM, i s'ha desenvolupat una plataforma experimental que ha permès validar-los en temps real a través d'un enllaç de fibra monomode estàndard (SSMF). El principal resultat d'aquesta tesi és haver demostrat experimentalment que amb el sistema proposat es pot arribar a una taxa binaria de 19,63 Gb/s amb una eficiència espectral de 8,07 bits/s/Hz sobre 20 km de SSMF, la qual cosa implica quasi duplicar les millors prestacions publicades fins aquest moment. Per completar el disseny del receptor, s'ha desenvolupat un algorisme de sincronització de temps basat en la correlació creuada entre un preàmbul conegut i el senyal OFDM rebut, el qual presenta una taxa d'error extremadament baixa, inclòs en condicions de molt baixa SNR, i el seu disseny optimitzat requereix menys recursos que altres sincronitzadors publicats fins el moment. També s'ha desenvolupat un processador de FFT de longitud variable mitjançant una arquitectura paral·lela segmentada que permet arribar fins una taxa de 10 GS/s en dispositius Virtex-7 amb una eficiència (àrea/velocitat) superior a la d'altres treballs publicats, i un equalitzador de canal basat en una tècnica d'estimació i compensació en freqüència, que utilitza un preàmbul característic per poder disminuir la complexitat hardware i augmentar la precisió de l'estimació. Tots els algorismes implementats a aquesta tesi doctoral han sigut dissenyats per processar 16 mostres en paral·lel, i així poder reduir la freqüència de rellotge (5 GHz/16) fins valors acceptables pels dispositius FPGA. / [EN] This thesis presents an in-depth exploration of the technical feasibility and achievable performance of a low-cost and high-speed optical communication system based on orthogonal frequency division multiplexing (OFDM) through the implementation of real-time digital signal processing algorithms over programmable logic devices (FPGA). Optical transmission systems based on intensity modulation and direct detection (IM/DD) is considered as one of the most interesting solutions for the deployment of the low-cost passive optical networks (PONs) that will be needed to cover the high traffic demand in the coming years. This demand is fueled, among others, by the significant increase of connected devices to the Internet, services and programs in the cloud, high definition video, etc. The main objective of this thesis is to achieve the maximum bitrate and spectral efficiency of an IM/DD PON OFDM system (using a single band and a single wavelength). To this end, the hardware architecture of a high-speed real-time OFDM receiver, including all the necessary algorithms to perform the detection and demodulation of the OFDM symbols, has been implemented in a Virtex-7 FPGA device at a clock frequency of 312.5 MHz using a digital analog converter with a sampling rate of 5 GS/s. To reach the best possible performance, all the system bandwidth has been employed and the OFDM subcarriers have been loaded according to the characteristics of the electro-optical channel. An experimental platform for optical transmission through standard single-mode fiber (SSMF) has been developed to evaluate in real-time the performance of the implemented receiver. The main result of this thesis is the experimental validation of the proposed system that has achieved a bit rate of 19.63 GS/s and a spectral efficiency of 8.07 bit/s/Hz over 20 km SSMF. These results almost double the best performance published to date. The receiver implementation included the design and development of several algorithms. First, it was designed a time synchronization algorithm (TSA) based on the cross-correlation between a known preamble and the received OFDM signal. This TSA has a good performance in low-SNR scenarios and its optimized design requires fewer resources than other synchronizers published in the literature. Second, a variable length parallel pipelined FFT processor has been implemented in a Virtex-7 device, it reaches a throughput of 10 GS/s with an efficiency (area/speed) higher than that of other published works. And finally, a channel equalizer working in the frequency domain to estimate and compensate channel distortions, which uses a known preamble to decrease the hardware complexity and increase the accuracy of the estimation, has been implemented. All the algorithms in this thesis have been developed to process 16 samples in parallel, thus reducing the required clock frequency (5 GHz/16) to acceptable values for the FPGA devices. / Deseo expresar mi gratitud a las autoridades de la Facultad Regional Buenos Aires de la Universidad Tecnológica Nacional por el apoyo económico y personal recibido durante la realización de esta tesis. / Bruno, JS. (2019). Algoritmos y arquitecturas hardware para la implementación de OFDM en sistemas de comunicaciones ópticos [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/119988 / TESIS

his work deals with the methods of creating computational models for the analysis of the chain drive of camshafts in combustion engines. Methods are compared of the simulation of the drive mechanism; a new method is also presented for the simulation of the tensioning and guide bar by means of a modal reduction of an elastic body in the Multibody system. The work describes individual parts of the chain gear and the mathematical formulation of differential equations of motion. Algorithms are also indicated describing the mutual interaction of bodies in contact. Computations are here described for the determination of individual parameters necessary for setting up a chain drive model. The tensile characteristics of the chain is determined by the FEM programme. The chain model is analyzed in several alternatives of arrangement. FEM calculations are described here of the rigidity of contacts between the chain and the chain wheels and between the chain and the guide bars. The computational model has been created in the MSC ADAMS programme. The computation is carried out for a stabilized speed of the crankshaft of 3,000, 4,500 and 6,000 rpm and for a continuous start from the idle state up to the speed of 6,000 rpm with a constant load of the crankshafts by the torsion moment. Computation is also carried out for loading the crankshafts with a torsion moment deduced from the cam shape. The courses of the quantity obtained are processed by means of FFT; Campbell diagrams have been constructed for their evaluation. The results have been compared with the modal analyses of the individual parts of the chain gear for the determination of their mutual interaction.

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Fast Fourier Transform is an efficient algorithm for computing the Discrete Fourier Transform (DFT) and one of the most important algorithms used in many digital signal processing applications over decades. This thesis presents an efficient implementation method of a 32-bit complex number 64-point FFT instruction on a micro-programmable processor. The implementation uses a radix-4 decimation in frequency (DIF) FFT structure. To reduce the total hardware budget, instead of floating-point computation, a block floating-point algorithm is applied to prevent the data overflow and make the most of the floating-point dynamic range, resulting in a highly efficient implementation with acceptable accuracy and SNR. The FFT instruction is divided into several sub-instructions that can be executed separately or chained together. The implementation for the instruction is realized in microcode, and the implementation method will be discussed in detail, including flowcharts and logical structures. This thesis is in cooperation with Imsys, some of the parameters such as 64-point FFT and data format are the requirements from Imsys. In order to realize an acceptable performance, several alternative implementation methods regarding twiddle factor formats and multiplication methods are investigated and discussed. The FFT instruction output has been verified on an Imsys Embla device with its embedded software test framework against an Excel model provided by Imsys. Several test functions are created to perform the functional verification for each sub-instruction and the entire FFT-IFFT chain. These test functions will be introduced and presented with their flowcharts. The evaluation mainly focuses on the performance of different implementation methods towards two aspects: the total execution time and the output accuracy and SNR. The measurement for the execution time is done by configuring a timer system built in the Imsys Embla device. The calculation for the output accuracy and SNR is according to given formulas. The best implementation method is chosen by comparing the SNR and execution cycle. Besides, the evaluation results are also compared with the excel model. During the instruction development process, the method of further possible improvement in the precision of the FFT instruction output has been discovered and is discussed in the future work chapter.

Modern medical ultrasound machines produce enormous amounts of data, as much as several gigabytes/sec in some systems. The challenges of generating, storing, processing and reproducing such voluminous data has motivated researchers to search for a feasible compression scheme for the received ultrasound radio frequency (RF) signals. Most of this work has concentrated on the digitized data available after sampling and A/D conversion. We are interested in the possibility of compression implemented directly on the received analog RF signals; hence, we focus on compression of the set of signals in a single receive aperture. We first investigate the model-free approaches to compression that have been proposed by previous researchers that involve applications of some of the well-known signal processing tools like Principal Component Analysis (PCA), wavelets, Fourier Transform, etc. We also consider Bandpass Prolate Spheroidal Functions (BPSFs) in this study. Then we consider the derivation of the optimal basis for the RF signals assuming a white noise model for spatial inhomogeneity field in tissue. We first derive an expression for the (time and space) autocorrelation function of the set of signals received in a linear aperture. This is then used to find the autocorrelation's eigenfunctions, which form an optimal basis for minimum mean-square error compression of the aperture signal set. We show that computation of the coefficients of the signal set with respect to the basis is approximated by calculation of real and imaginary part of the Fourier Series coefficients for the received signal at each aperture element, with frequencies slightly scaled by aperture position, followed by linear combinations of corresponding frequency components across the aperture. The combination weights at each frequency are determined by the eigenvectors of a matrix whose entries are averaged cross-spectral coefficients of the received signal set at that frequency. The principal eigenvector generates a combination that corresponds to a variation on the standard delay-and-sum beamformed aperture center line, while the combinations from other eigenvectors represent aperture information that is not contained in the beamformed line. We then consider how to use the autocorrelation's eigenfunctions and eigenvalues to generate a linear minimum mean-square error beamformer for the center line of each aperture. Finally, we compare the performances of the optimal compression basis and to that of the 2D Fourier Transform.

This thesis discusses the design considerations for a machine conditioning sensor utilizing Bluetooth low energy (BLE).