To efficiently capture signal events when performing analog measurements, a competent toolbox is required. In this master thesis, a system for frequency domain triggering is designed and implemented. The implemented system provides advanced frequency domain trigger conditions, in order to ease the capture of a desired signal event. A real-time 1024-point pipelined feedforward FFT-core is implemented to transform the signal from the time domain to the frequency domain. The system is designed and synthesized for a Virtex-6 FPGA (XC6VLX240T) and is integrated into SP Devices’ digitizer ADQ1600. The implemented system is able to handle a continuous stream of 1.6GS/s at 16-bit. A small software API is developed that provides runtime configuration of the Triggering conditions.

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In this thesis we evaluate the prospects of performing real-time digital signal processing on a graphics processing unit (GPU) when linked together with a high-performance digitizer. A graphics card is acquired and an implementation developed that address issues such as transportation of data and capability of coping with the throughput of the data stream. Furthermore, it consists of an algorithm for executing consecutive fast Fourier transforms on the digitized signal together with averaging and visualization of the output spectrum. An empirical approach has been used when researching different available options for streaming data. For better performance, an analysis of the introduced noise of using single-precision over double-precision has been performed to decide on the required precision in the context of this thesis. The choice of graphics card is based on an empirical investigation coupled with a measurement-based approach. An implementation in single-precision with streaming from the digitizer, by means of double buffering in CPU RAM, capable of speeds up to 3.0 GB/s is presented. Measurements indicate that even higher bandwidths are possible without overflowing the GPU. Tests show that the implementation is capable of computing the spectrum for transform sizes of <img src="http://www.diva-portal.org/cgi-bin/mimetex.cgi?2%5E%7B21%7D" />, however measurements indicate that higher and lower transform sizes are possible. The results of the computations are visualized in real-time.

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A high-efficiency gamma-ray counting system has been built at Los Alamos National Laboratory for use in analyzing nuclear forensics samples. This system consists of two clover high-purity germanium detectors and is surrounded by a thallium-doped sodium iodide annulus. Special precautions have been taken to ensure the system has a low background. The system is connected to XIA Pixie-4 fast digitizers and collects data in list-mode. This work is split into two main parts. The first part describes the proper steps and techniques to initialize the settings of a detector system connected to fast digitizers in order to optimize the system for resolution and throughput. The various counting modes for this particular system are described in detail, including the benefits and drawbacks of each mode. Steps are then shown to characterize the system by obtaining efficiency curves for various counting modes and sample geometries. Because of the close counting geometry involved with this system, true-coincidence summing factors must be calculated, and are done so in part by measuring the peak-to-total ratios of the system in its various counting modes across a wide energy range. The dead-time for the system can be complicated due to the multiple inputs of the system. Techniques for calculating the dead-time of multiple-detector systems are discussed. The second part of this work shows the system's usefulness in analyzing nuclear forensics samples, specifically irradiated enriched uranium. Three fission product parent-daughter pairs of different lifetimes are analyzed over a course of six months. The activities of each nuclide are calculated at each time step. Age dating techniques using the parent-daughter pairs are discussed, as well as the detection limits of each nuclide for a range of sample ages. Finally, avenues for further research are presented, as well as potential sources of error or uncertainty for this work. / text

Increasing sampling rates and sampling accuracies of analog-to-digital converters (ADCs) are growing the importance of digital data acquisition and signal processing for applications requiring high bandwidth. In this context, this work is focused on researching and developing new techniques and a new system architecture for optimal throughput and minimal intrinsic dead time. The investigations of this work concentrate on event processing systems by pulse shaping on SuperSampleRate (SSR) ADC data streams. SSR ADC data streams are data streams which require processing of more than one sample per clock cycle by digital circuits. To implement data processing in this work only Field Programmable Gate Arrays (FPGAs) are used, as they provide the right approach for high throughput and minimum dead time with ability to adapt to high- application-specific circuits afterwards. As a result of this work a system architecture was developed which decouples the event acquisition and their processing inside the FPGA. This property is realized by a special FIFO structure in the FPGA. This concept achieves an intrinsic dead time of one ADC sample period and allows pre-processing of all channels by multiple instantiated processing cores and scheduling in hardware. By means of this new system architecture, two conventional scientific measuring instruments based on analog technology were improved by digital data acquisition and signal processing. These measuring instruments are a spectrometer for time-differential perturbed angular correlations (TDPAC) and a digital spectrometer and data acquisition system at a nuclear microprobe for ion beam analysis and imaging. Both measuring instruments detect elementary particles or radiation emitted by the measuring sample by detectors as events. The time curves of several analog detector output signals (channels) are now recorded by ADCs and forwarded without loss as SSR data streams to one FPGA. The hardware used here are FPGA digitizers which isolate the data acquisition and subsequent pre-processing by FPGAs into modules. The improvement of the measuring efficiency of the two digital measuring instruments was achieved by minimizing the dead time, increasing the throughput, and by matching their time and energy resolutions with the conventional measuring instruments. Specifically to enable better time and energy resolutions combined with maximum throughput, this work has developed and implemented parallel processing SSR FIR and SSR IIR filters for pulse shaping as processing cores in the FPGAs which can handle multiple samples per clock cycle. To match the time resolution performance of conventional Constant Fraction Discriminators (CFDs) these filter implementations realize a digital Constant Fraction Trigger (CFT) with fractional delays (below one sampling period). In this work the energy resolution was optimized by implementing a transfer function adjustable SSR IIR filter. Thus the filter provides maximum flexibility for pulse shaping of different detector types. By implementing the computationally intensive pre-processing in FPGAs, the measuring instruments could be equipped with only one underutilized PC, which can now implement new functionalities. These functionalities include a runtime-optimized coincidence measurement of stretched cascades (like for 180mHf) for the TDPAC spectrometer and a digital pileup rejection for the data acquisition system for ion beam analysis. / Die digitale Messwerterfassung und -verarbeitung erhält unter anderem durch steigende Abtastraten und Abtastgenauigkeiten von Analog-Digital-Wandlern (ADCs) wachsende Bedeutung für Anwendungen, welche eine hohe Bandbreite voraussetzen. In diesem Rahmen widmet sich diese Arbeit der Erforschung und Entwicklung neuer Techniken und einer neuen Systemarchitektur, mit denen eine Datenaufnahme und anschließende Signalverarbeitung, bei optimalem Durchsatz und minimaler intrinsische Totzeit umgesetzt werden kann. Die Untersuchungen fokussieren sich dabei auf Systeme zur Ereignisverarbeitung durch Impulsformung (pulse shaping) auf SuperSampleRate(SSR)-ADC-Datenströmen. SSR-ADC-Datenströme sind dabei ADC-Datenströme, welche eine Verarbeitung durch digitale Schaltungen benötigen, bei denen mehr als ein Sample pro Taktzyklus behandelt werden muss, um Datenverlust zu verhindern. Zur Implementierung der Datenverarbeitung kommen dazu ausschließlich Field Programmable Gate Arrays (FPGAs) zum Einsatz, da diese den passenden Ansatz für digitale Schaltungen mit hohen Durchsatz und minimaler Totzeit mit gleichzeitiger nachträglicher Anpassbarkeit für hoch anwendungsspezifische Schaltungen bieten. Als Ergebnis wurde in dieser Arbeit eine Systemarchitektur entwickelt, welche die Ereigniserfassung und deren Verarbeitung im FPGA voneinander entkoppelt. Dies wird durch eine im FPGA realisierte FIFO-Struktur ermöglicht. Durch dieses Konzept wird eine intrinsische Totzeit der Systeme in der Größenordnung der ADC-Abtastperiodenlänge erreicht und eine Vorverarbeitung aller Kanäle durch mehrfache instanziierte Verarbeitungskerne und Scheduling in Hardware ermöglicht. Mittels dieser neuen Systemarchitektur werden zwei auf analogtechnisch basierende konventionelle wissenschaftliche Messinstrumente, durch digitale Messwerterfassung und Signalverarbeitung, verbessert. Bei diesen Messinstrumenten handelt es sich um ein Spektrometer zur zeitaufgelösten gestörten Winkelkorrelation (engl. Time Differential Perturbed Angular Correlation (kurz TDPAC-Spektrometer)) und ein Datenerfassungssystem zur ortsaufgelösten elementspezifischen Ionenstrahlanalyse und Ionenstrahlmikroskopie, welche im Wesentlichen von der Messprobe emittierte und durch Detektoren erfasste Elementarteilchen oder Strahlung als Ereignisse verarbeiten. Die Verläufe der analogen Detektorausgangssignale werden dabei mittels ADCs erfasst und verlustfrei als SSR-Datenströme an einen FPGA weitergeleitet. Dabei werden mehrere ADC-Datenströme (dann Kanäle genannt) von einem FPGA verarbeitet. Als Hardware kommen hier FPGA-Digitizer zum Einsatz. Diese Module isolieren die digitale Messwerterfassung durch ADCs und eine anschließende Vorverarbeitung von FPGAs, deren digitale Schaltung individuell implementiert werden kann, in eine Hardware. Eine Verbesserung der Messeffizienz der beiden digitalisierten Messinstrumente konnte durch die Minimierung der Totzeit, die Erhöhung des Durchsatzes aber auch durch die Anknüpfung ihrer Zeit- und Energieauflösung der detektierten Ereignisse erreicht werden. Speziell zur Ermöglichung besserer Zeit- und Energieauflösungen von Detektorereignissen mit maximalem Durchsatz wurden in dieser Arbeit SSR-FIR- und SSR-IIR-Filter zur Impulsformung als Verarbeitungskerne in den verwendeten FPGAs implementiert, welche pro Taktzyklus mehrere Samples verarbeiten können. Diese Filterimplementierungen setzen zur Optimierung der Zeitauflösung im Subsample-Bereich mit den Constant Fraction Trigger (CFT) an der Leistungsfähigkeit konventioneller Constant Fraction Discriminator (CFDs) an und ermöglichen ebenso Fractional Delays (Zeitverzögerungen unter einer Abtastperiode). Die Energieauflösung wurde in dieser Arbeit dadurch optimiert, dass der entwickelte SSR-IIR-Filter in seiner Übertragungsfunktion anpassbar ist und so maximale Flexibilität zur Impulsformung unterschiedlicher Detektortypen bietet. Durch die Umsetzung der rechenintensiven Vorverarbeitung in FPGAs konnten die Messinstrumente mit lediglich einem Mess-PC ausgestattet werden, welcher nun neue Funktionalitäten umsetzen kann. Zu diesen Funktionalitäten gehört eine laufzeitoptimierte Koinzidenzmessung gestreckter Kaskaden (Kaskade mit mehr als einem Start-Ereignis) für das TDPAC-Spektrometer und eine digitale Pileup-Verwerfung für das Datenerfassungssystem zur Ionenstrahlanalyse.

Le Radiohéliographe de Nançay est le seul instrument dédié à l'imagerie du soleil en ondes décimétriques-métriques. Il fonctionne sur le principe de l'interférométrie, en utilisant 47 antennes essentiellement réparties sur des axes est-ouest (3,2 km) et nord-sud (2,5 km). Cette étude a pour but d'explorer un nouveau concept de numérisation propre à la radioastronomie du futur, appliquée ici à l'interférométrie solaire. Elle porte sur la numérisation rapide d'un système synchronisé en sortie d'antennes. Ces aspects "numérisation rapide" et "synchronisation" sont d'une importance capitale pour les prochains radiotélescopes du futur. Ils permettent de simplifier les chaînes de réception radiofréquence et de diminuer la consommation électrique ainsi que les coûts d'entretien et de la maintenance. L'application à l'observation du soleil comporte cependant des contraintes originales, comme la grande dynamique des signaux, qui ne sont pas prises en compte actuellement dans les études en cours pour les radiotélescopes du futur. Le radiohéliographe actuel a une chaîne de réception analogique avec une numérisation centralisée. La commutation entre les différentes fréquences dans la bande 150-450~MHz est réalisée d'une façon analogique et temporelle. Ceci nécessite beaucoup de calibrations analogiques et oblige de figer la gamme des fréquences (10 fréquences de largeur 1~MHz). De plus, en interférométrie métrique, les très grandes longueurs de câbles coaxiales sont onéreuses. Les signaux transmis des antennes au récepteur sont toujours sources d'erreurs et des fluctuations importantes réduisent l'information radiofréquence. Toutefois, apporter une numérisation complète de la bande (300~MHz) permet d'avoir de la souplesse dans le traitement et l'analyse des données (résolution fréquentielle et la possibilité d'observer plusieurs bandes simultanément, traitement des parasites). Ceci engendre la nécessité d'avoir une très grande précision des horloges (0,7~ps d'erreur de phase) pour cadencer des ADC (Analog-to-Digital-Converter) large bande (1~GHz d'horloge). L'objectif principal de la thèse est d'étudier la synchronisation pour l'application à un réseau d'antennes multi-réparties. Le saut technologique ainsi induit et les concepts étudiés sont un enjeu grandissant dans les grands projets européens et internationaux. / The Nançay Radioheliograph is the only instrument dedicated to the solar corona imaging in the 150-450 MHz frequency band. It operates on the principle of interferometry, using 47 antennas essentially distributed on the east-west (3.2 km) and north-south (2.5 km) axes. This study aims to explore a new technical concept for future radio astronomy, applied to solar interferometer. It deals with the rapid digitization of a synchronized system at the antenna sides. High speed digitization and high accuracy synchronization are the most important aspects for future radio telescopes. They make it possible to simplify radiofrequency reception chains and reduce their power consumption, as well as maintenance costs and complexity. The application to the observation of the sun, however, has some original constraints, such as the great dynamics of the signals, which are not taken into account in the current studies for future radio telescopes. The current radio telescope has an analog receiver with a centralized digitization. The switching time between each frequency (10 frequencies of 1 MHz width) in 150-450 MHz band analyzed introduce latency in solar images processing, also decrease the signal-to-noise ratio. In addition, in metric interferometry, the several lengths of coaxial cables in which the signal is transported from the antennas to the receiver always cause significant errors and fluctuations in the radiofrequency reception chains. Providing full digitization of the band (300 MHz) allows more flexibility in data processing and analyzing (frequency resolution and the ability to observe multiple bands simultaneously). This required high clock accuracy (0.7 ps of jitter) for ADCs clocks (1 GHz clock). Therefore, the main objective of this thesis is to reach a sub-ns global time synchronization of distributed networks such as radio interferometer array as the Nançay Radioheliograph. The technological leap thus induced is a growing challenge in major European and international projects.

Purpose of this document is acquite reader with basic principles of 3D model digitalization.This work describes general overview of 3D scanning devices, their physical principle and measurements methods. Next part of this document  describes basic method for polygonal mesh processing as smoothing an decimation which are necessary for 3D model processing.This document contains also algorithms description of implementation, user interface and publication part through WWW. Fundamental essence of this diploma thesis will be introduction with general principles of 3D scanning and working with Minolta VIVID-700 3D digitizer which is placed on our faculty. At the end are mentioned results evalution,demostration examples and next supposed project advancement.