Design exploration and performance strategies towards power-efficient FPGA-based achitectures for sound source localization

Many applications rely on MEMS microphone arrays for locating sound sources prior to their execution. Those applications not only are executed under real-time constraints but also are often embedded on low-power devices. These environments become challenging when increasing the number of microphones or requiring dynamic responses. Field-Programmable Gate Arrays (FPGAs) are usually chosen due to their flexibility and computational power. This work intends to guide the design of reconfigurable acoustic beamforming architectures, which are not only able to accurately determine the sound Direction-Of-Arrival (DoA) but also capable to satisfy the most demanding applications in terms of power efficiency. Design considerations of the required operations performing the sound location are discussed and analysed in order to facilitate the elaboration of reconfigurable acoustic beamforming architectures. Performance strategies are proposed and evaluated based on the characteristics of the presented architecture. This power-efficient architecture is compared to a different architecture prioritizing performance in order to reveal the unavoidable design trade-offs

Contribution to Efficient Use of Narrowband Radio Channel

Předkládaná práce se soustředí na problematiku využívání úzkopásmového rádiového kanálu rádiovými modemy, které jsou určené pro průmyslové aplikace pozemní pohyblivé rádiové služby, specifikované v dominantní míře Evropským standardem ETSI EN 300 113. Tato rádiová zařízení se používají v kmitočtových pásmech od 30 MHz do 1 GHz s nejčastěji přidělovanou šířkou pásma 25 kHz a ve většině svých instalací jsou využívána ve fixních nebo mobilních bezdrátových sítích. Mezi typické oblasti použití patří zejména datová telemetrie, aplikace typu SCADA, nebo monitorování transportu strategických surovin. Za hlavní znaky popisovaného systému lze označit komunikační pokrytí značných vzdáleností, dané především vysokou výkonovou účinnosti datového přenosu a využívaní efektivních přístupových technik na rádiový kanál se semiduplexním komunikačním režimem. Striktní požadavky na elektromagnetickou kompatibilitu umožňují těmto zařízením využívat spektrum i v oblastech kmitočtově blízkým jiným komunikačním systémům bez nutnosti vkládání dodatečných ochranných frekvenčních pásem. Úzkopásmové rádiové komunikační systémy, v současnosti používají převážně exponenciální digitální modulace s konstantní modulační obálkou zejména z důvodů velice striktních omezení pro velikost výkonu vyzářeného do sousedního kanálu. Dosahují tak pouze kompromisních hodnot komunikační účinnosti. Úpravy limitů příslušných rádiových parametrů a rychlý rozvoj prostředků číslicového zpracování signálu v nedávné době, dnes umožňují ekonomicky přijatelné využití spektrálně efektivnějších modulačních technik i v těch oblastech, kde je prioritní využívání úzkých rádiových kanálů. Cílem předkládané disertační práce je proto výzkum postupů směřující ke sjednocení výhodných vlastností lineárních a nelineárních modulací v moderní konstrukci úzkopásmového rádiového modemu. Účelem tohoto výzkumu je efektivní a „ekologické“ využívání přidělené části frekvenčního spektra. Mezi hlavní dílčí problémy, jimiž se předkládaná práce zabývá, lze zařadit zejména tyto: Nyquistova modulační filtrace, navrhovaná s ohledem na minimalizaci nežádoucích elektromagnetických interferencí, efektivní číslicové algoritmy frekvenční demodulace a rychlé rámcové a symbolové synchronizace. Součástí práce je dále analýza navrhovaného řešení z pohledu celkové konstrukce programově definovaného rádiového modemu v rovině simulací při vyšetřování robustnosti datového přenosu rádiovým kanálem s bílým Gaussovským šumem nebo kanálem s únikem v důsledku mnohacestného šíření signálu. Závěr práce je pak zaměřen na prezentování výsledků praktické části projektu, v níž byly testovány, měřeny a analyzovány dvě prototypové konstrukce rádiového zařízení. Tato finální část práce obsahuje i praktická doporučení, vedoucí k vyššímu stupni využitelnosti spektrálně efektivnějších komunikačních režimů v oblasti budoucí generace úzkopásmových zařízení pozemní pohyblivé rádiové služby.he industrial narrowband land mobile radio (LMR) devices, as considered in this dissertation project, has been subject to European standard ETSI EN 300 113. The system operates on frequencies between 30 MHz and 1 GHz, with channel separations of up to 25 kHz, and is intended for private, fixed, or mobile, radio packet switching networks. Data telemetry, SCADA, maritime and police radio services; traffic monitoring; gas, water, and electricity producing factories are the typical system applications. Long distance coverage, high power efficiency, and efficient channel access techniques in half duplex operation are the primary advantages the system relays on. Very low level of adjacent channel power emissions and robust radio receiver architectures, with high dynamic range, enable for a system’s coexistence with various communication standards, without the additional guard band frequency intervals. On the other hand, the strict limitations of the referenced standard as well as the state of the technology, has hindered the increase in communication efficiency, with which the system has used its occupied bandwidth. New modifications and improvements are needed to the standard itself and to the up-to-date architectures of narrowband LMR devices, to make the utilization of more efficient modes of system operation practically realizable. The main objective of this dissertation thesis is therefore to find a practical way how to combine the favorable properties of the advanced nonlinear and linear digital modulation techniques in a single digital modem solution, in order to increase the efficiency of the narrowband radio channel usage allocated to the new generation of the industrial LMR devices. The main attention is given to the particular areas of digital modem design such as proposal of the new family of the Nyquist filters minimizing the adjacent channel interference, design and analysis of the efficient algorithms for frequency discrimination, fast frame and symbol

A 1.8 V 25 Mbps CMOS single-phase, phase-locked loop-based BPSK, QPSK demodulator

A single-phase binary/quadrature phase-shift keying (BPSK/QPSK) demodulator basing on a phase-locked loop (PLL) is described. The demodulator relies on a linear characteristic a rising-edge RESET/SET flip-flop (RSFF) employed as a phase detector. The phase controller takes the average output from the RSFF and performs a sub-ranging/re-scaling operation to provide an input signal to a voltage-controlled oscillator (VCO). The demodulator is truly modular which theoretically can be extended for a multiple-PSK (m-PSK) signal. Symbol-error rate analysis has also been extensively carried out. The proposed BPSK and QPSK demodulators have been fabricated in a 0.18-mm digital complementary metal–oxide–semiconductor (CMOS) process where they operate from a single supply of 1.8 V. At a carrier frequency of 60 MHz, the BPSK and QPSK demodulators achieved maximum symbol rates of 25 and 12.5 Msymb/s while consuming 0.68 and 0.79 mW, respectively. At these maximum symbol rates, the BPSK and QPSK demodulators deliver symbol-error rates less than 7.9×10-10 and 9.8×10-10, respectively where their corresponding energy per bit figures were at 27.2 and 31.7 pJ

Embedded system for real-time digital processing of medical Ultrasound Doppler signals

Ultrasound (US) Doppler systems are routinely used for the diagnosis of cardiovascular diseases. Depending on the application, either single tone bursts or more complex waveforms are periodically transmitted throughout a piezoelectric transducer towards the region of interest. Extraction of Doppler information from echoes backscattered from moving blood cells typically involves coherent demodulation and matched filtering of the received signal, followed by a suitable processing module. In this paper, we present an embedded Doppler US system which has been designed as open research platform, programmable according to a variety of strategies in both transmission and reception. By suitably sharing the processing tasks between a state-of-the-art FGPA and a DSP, the system can be used in several medical US applications. As reference examples, the detection of microemboli in cerebral circulation and the measurement of wall _distension_ in carotid arteries are finally presented

Modulation Techniques for Biomedical Implanted Devices and Their Challenges

Implanted medical devices are very important electronic devices because of their usefulness in monitoring and diagnosis, safety and comfort for patients. Since 1950s, remarkable efforts have been undertaken for the development of bio-medical implanted and wireless telemetry bio-devices. Issues such as design of suitable modulation methods, use of power and monitoring devices, transfer energy from external to internal parts with high efficiency and high data rates and low power consumption all play an important role in the development of implantable devices. This paper provides a comprehensive survey on various modulation and demodulation techniques such as amplitude shift keying (ASK), frequency shift keying (FSK) and phase shift keying (PSK) of the existing wireless implanted devices. The details of specifications, including carrier frequency, CMOS size, data rate, power consumption and supply, chip area and application of the various modulation schemes of the implanted devices are investigated and summarized in the tables along with the corresponding key references. Current challenges and problems of the typical modulation applications of these technologies are illustrated with a brief suggestions and discussion for the progress of implanted device research in the future. It is observed that the prime requisites for the good quality of the implanted devices and their reliability are the energy transformation, data rate, CMOS size, power consumption and operation frequency. This review will hopefully lead to increasing efforts towards the development of low powered, high efficient, high data rate and reliable implanted devices

Spatially Coupled Codes and Optical Fiber Communications: An Ideal Match?

In this paper, we highlight the class of spatially coupled codes and discuss their applicability to long-haul and submarine optical communication systems. We first demonstrate how to optimize irregular spatially coupled LDPC codes for their use in optical communications with limited decoding hardware complexity and then present simulation results with an FPGA-based decoder where we show that very low error rates can be achieved and that conventional block-based LDPC codes can be outperformed. In the second part of the paper, we focus on the combination of spatially coupled LDPC codes with different demodulators and detectors, important for future systems with adaptive modulation and for varying channel characteristics. We demonstrate that SC codes can be employed as universal, channel-agnostic coding schemes.Comment: Invited paper to be presented in the special session on "Signal Processing, Coding, and Information Theory for Optical Communications" at IEEE SPAWC 201

衛星受信機のための動的部分再構成型復調器の設計と実装

九州工業大学博士学位論文 学位記番号：工博甲第461号 学位授与年月日：平成30年9月21日1: Introduction|2: Background and Literature Review|3: Dynamic Partial Reconfigurable Demodulation System – Classification|4: DPRDS – DPR|5: ICAP Multiple Access by DPRDS and SEU Mitigation Systems|6: Conclusion and Future Perspective九州工業大学平成30年

Analog least mean square loop for self-interference cancellation: A practical perspective

©2020 by the authors. Licensee MDPI, Basel, Switzerland. Self-interference (SI) is the key issue that prevents in-band full-duplex (IBFD) communications from being practical. Analog multi-tap adaptive filter is an efficient structure to cancel SI since it can capture the nonlinear components and noise in the transmitted signal. Analog least mean square (ALMS) loop is a simple adaptive filter that can be implemented by purely analog means to sufficiently mitigate SI. Comprehensive analyses on the behaviors of the ALMS loop have been published in the literature. This paper proposes a practical structure and presents an implementation of the ALMS loop. By employing off-the-shelf components, a prototype of the ALMS loop including two taps is implemented for an IBFD system operating at the carrier frequency of 2.4 GHz. The prototype is firstly evaluated in a single carrier signaling IBFD system with 20 MHz and 50 MHz bandwidths, respectively. Measured results show that the ALMS loop can provide 39 dB and 33 dB of SI cancellation in the radio frequency domain for the two bandwidths, respectively. Furthermore, the impact of the roll-off factor of the pulse shaping filter on the SI cancellation level provided by the prototype is presented. Finally, the experiment with multicarrier signaling shows that the performance of the ALMS loop is the same as that in the single carrier system. These experimental results validate the theoretical analyses presented in our previous publications on the ALMS loop behaviors

Design, analysis and implementation of a versatile low level radio frequency system for accelerating cavities

179 p.[ES]En esta tesis se describen diversas soluciones analógicas y digitales para realizar sistemas de control LLRF (Radio Frecuencia de Bajo Nivel) para cavidades resonantes de radiofrecuencia de aceleradores de partículas. Para analizar dichas cavidades, se desarrolla un modelo genérico que representa la respuesta dinámica de la cavidad bajo la influencia del haz de partículas. Después, se usa este modelo para desarrollar y analizar un sistema analógico de LLRF para el booster' del sincrotrón ALBA, así como un sistema LLRF digital para el linac de la futura Fuente Europea de Protones y Neutrones de Bilbao (ESS-Bilbao). A continuación, se presentan los detalles del diseño e implementación de los dos sistemas LLRF aludidos, así como los resultados experimentales obtenidos en distintas cavidades de radiofrecuencia, así verificando la validez de los dos diseños propuestos. También, se presenta el diseño básico de la electrónica de RF de un sistema de Monitorización de la Posición del Haz de Partículas (BPM) y los resultados preliminares obtenidos con un haz simulado en un banco de ensayos desarrollado al efecto. Hay dos consideraciones importantes a la hora de desarrollar un modelo eléctrico de cavidades radiofrecuencia útil para analizar el sistema o diseñar un lazo de LLRF: la respuesta transitoria y los desajustes de impedancia. Sin embargo, en la literatura raramente se consideran estas cuestiones de manera conjunta, y una suele prevalecer sobre la otra, dependiendo de si la cavidad de radiofrecuencia se mira desde una perspectiva de alta potencia o de LLRF. En esta tesis, en primer lugar, se desarrolla un modelo para representar los aspectos más importantes de la cavidad, incluyendo desajustes de impedancia, potencia reflejada y la respuesta transitoria, por ejemplo en el arranque del sistema o en los instantes de llegada del haz de partículas que carga la cavidad. Como un caso especial, se aplica el modelo a las cavidades RF del anillo de almacenamiento (storage ring) de ALBA, estudiando así los efectos de carga del haz (beam loading), el arranque del sistema y los retardos en la respuesta de los lazos de regulación. Para simular estos lazos, se emplea una técnica matemática para hacer corresponder la frecuencia resonante de la cavidad a banda base, obteniendo de esta manera un modelo equivalente en banda base de la cavidad, con una respuesta aproximadamente igual al modelo convencional RF, pero con una velocidad de simulación mucho mayor. A continuación, se presenta el diseño y la implementación del sistema de LLRF analógico del booster' de ALBA, basado en lazos de realimentación de las señales IQ del sistema. Se miden los parámetros importantes del LLRF operando la cavidad tanto a baja como a alta potencia de RF, verificando así el diseño propuesto. Finalmente, se presenta el diseño, implementación y diversos resultados experimentales del sistema LLRF digital pulsado que hemos desarrollado para el Cuadrupolo de Radio Frecuencia (RFQ) del Rutherford Appleton Laboratory - Front End Test Stand (Oxfordshire, Inglaterra) y para el futuro linac de ESS-Bilbao. En lugar de emplear un front-end' analógico estándar que convierta las señales medidas en la cavidad a una Frecuencia Intermedia (IF) para a continuación submuestrear este señal, en este diseño usamos un demodulador IQ analógico, que transforma directamente las señales RF medidas en sus componentes En-fase (I) y Cuadratura (Q) en banda base. La ventaja principal de usar este método es eliminar la necesidad para un sistema preciso y complejo de sincronización y timing', lo cual da lugar a un sistema LLRF simple y versátil que puede servir para un rango grande de frecuencias y virtualmente para cualquier aplicación LLRF, sean pulsadas, en rampa o de onda continua (CW). Los errores asociados al uso de demoduladores de IQ analógicos han sido identificados y corregidos mediante algoritmos implementados en la FPGA y por medio del ajuste apropiado de los parámetros del lazo de control. Además, se ha desarrollado un modelo equivalente en banda base del RFQ en MATLAB-Simulink para estudiar su respuesta transitoria en condiciones de carga del haz y en presencia de errores de fase y retardos. Los resultados experimentales obtenidos con una cavidad de prueba y un modelo en cobre del RFQ verifican que en lazo cerrado pueden obtenerse campos acelerantes con niveles de estabilidad de amplitud y fase superiores al 1 por ciento y un grado respectivamente, además de un margen de fase mayor de +/- 50 grados que confiere robustez al sistema, conservando al mismo tiempo la linealidad y el ancho de banda de los lazos de regulación, y cumpliendo por tanto sobradamente las especificaciones requeridas para el acelerador[EN]This thesis describes analog and digital Low-Level Radio Frequency (LLRF) solutions applied to RF cavities of particle accelerators. For cavity analysis, a generic electrical model is developed to represent the cavity dynamic response under a beam. This model is then used as the basis for the design and analysis of two LLRF systems being the analog LLRF of the ALBA booster and the digital LLRF of the future Bilbao Proton and Neutron Source (ESS-Bilbao) linac. Details of the design and implementation of both LLRF systems are given followed by the experimental results obtained with di erent types of cavities verifying the validity of both LLRF systems. Also, the basic design of the ESS-Bilbao Beam Position Monitoring (BPM) RF electronics is described and the preliminary results obtained with a BPM test bench are presented. There are two important considerations in the development of an electrical model analogy for RF cavities to be used for system analysis or LLRF loop design, being: transient response and cavity impedance mismatches. In the literature, however, either one or both of these issues are often neglected depending on whether the RF cavity is being looked at from a high-power or a LLRF perspective. In this thesis, in the rst place, a transient model for RF cavities under beam loading is developed so that it represents the important RF aspects of the cavity such as impedance mismatches and re ected voltage as well as its transient response, for example at start-up or upon beam arrival. As a special case, the model is applied to the RF cavity of the ALBA storage ring to study the e ects arising from beam loading, system start-up and delays on the performance of the LLRF regulation loops. For the simulation of the regulation loops in time domain a mathematical technique is introduced to map the cavity resonant frequency to baseband, leading to a baseband-equivalent model for the cavity with almost the same results as the conventional RF model but with signi cantly higher simulation speed. In the continuation, the design and implementation of the IQ-based analog LLRF system for the ALBA booster is presented. The important LLRF parameters have been measured with the cavity running under low and high RF power and compared to the speci cations verifying that all the requirements can be met with the proposed LLRF design. Finally, the design and some performance results of the pulsed digital LLRF for the RFQ (Radio Frequency Quadrupole) systems of Rutherford Appleton Laboratory - Front End Test Stand and the future ESS-Bilbao linac are presented. Contrary to the standard digital LLRF front-end in which the cavity probe voltage is rst down converted to an Intermediate Frequency (IF) and then subsampled, in this design, an analog IQ demodulator has been used to directly convert the probe voltage to I (In-phase) and Q (Quadrature-phase) components in baseband. The main advantage of this method is that the need for a precise synchronization and timing system for down-conversion and ADC sampling is eliminated leading to a simple and versatile design which can be used for a large variety of RF frequencies and virtually any LLRF application including CW, ramping and pulsed. The errors associated with the use of analog IQ demodulators have been identi ed and corrected by FPGA algorithms and proper setting of the control loop parameters. Furthermore, a basebandequivalent model for the RF plant is developed in MATLAB-Simulink to study the RFQ transient response under beam loading in the presence of phase and delay errors. The practical results obtained with a mock-up cavity and an RFQ cold model verify that amplitude and phase stabilities in the acceleration elds down to a fraction of one percent and one degree, and phase margins larger than 50 can be achieved with this method preserving the linearity and bandwidth of the regulation loops and ful lling the required speci cations for the accelerator

Fiber-on-Chip: Digital Emulation of Channel Impairments for Real-Time DSP Evaluation

We describe the Fiber-on-Chip (FoC) approach to verification of digital signal processing (DSP) circuits, where digital models of a fiber-optic communication system are implemented in the same hardware as the DSP under test. The approach can enable cost-effective long-term DSP evaluations without the need for complex optical-electronic testbeds with high-speed interfaces, shortening verification time and enabling deep bit-error rate evaluations. Our FoC system currently contains a digital model of a transmitter generating a pseudo-random bitstream and a digital model of a channel with additive white Gaussian noise, phase noise and polarization-mode dispersion. In addition, the FoC system contains digital features for real-time control of channel parameters, using low-speed communication interfaces, and for autonomous real-time analysis, which enable us to batch multiple unsupervised emulations on the same hardware. The FoC system can target both field-programmable gate arrays, for fast evaluation of fixed-point logic, and application-specific integrated circuits, for accurate power dissipation measurements