Thematische Bibliographien / Coherent sampling

Inhaltsverzeichnis

  1. Zeitschriftenartikel
  2. Dissertationen
  3. Buchteile
  4. Konferenzberichte
  5. Berichte der Organisationen

Auswahl der wissenschaftlichen Literatur zum Thema „Coherent sampling“

Autor: Grafiati
Veröffentlicht am 28. Juni 2021
Zuletzt aktualisiert am 17. Februar 2022

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Zeitschriftenartikel zum Thema "Coherent sampling"

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Kim, Inwoong, Cheolhwan Kim und Guifang Li. „Requirements for the sampling source in coherent linear sampling“. Optics Express 12, Nr. 12 (2004): 2723. http://dx.doi.org/10.1364/opex.12.002723.

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Kray, Stefan, Felix Spöler, Thomas Hellerer und Heinrich Kurz. „Electronically controlled coherent linear optical sampling for optical coherence tomography“. Optics Express 18, Nr. 10 (28.04.2010): 9976. http://dx.doi.org/10.1364/oe.18.009976.

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Yang, Honglei, Shengkang Zhang, Huan Zhao und Jun Ge. „Phase-coherent asynchronous optical sampling system“. Optics Express 28, Nr. 24 (20.11.2020): 37040. http://dx.doi.org/10.1364/oe.405074.

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4

Xin Chen, Xiaobo Xie, Inwoong Kim, Guifang Li, Hanyi Zhang und Bingkun Zhou. „Coherent Detection Using Optical Time-Domain Sampling“. IEEE Photonics Technology Letters 21, Nr. 5 (März 2009): 286–88. http://dx.doi.org/10.1109/lpt.2008.2010868.

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Agrež, Dušan. „Power measurement in the non-coherent sampling“. Measurement 41, Nr. 3 (April 2008): 230–35. http://dx.doi.org/10.1016/j.measurement.2006.12.005.

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Chaturvedi, S. „The sampling theorem and coherent state systems“. Optics and Spectroscopy 103, Nr. 3 (September 2007): 405–10. http://dx.doi.org/10.1134/s0030400x07090093.

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Avitzour, D. „SNR/bandwidth tradeoff in coherent radar sampling“. IEEE Transactions on Aerospace and Electronic Systems 26, Nr. 2 (März 1990): 403–5. http://dx.doi.org/10.1109/7.53447.

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Agrez, Dusan. „Estimation of the signal component from random equivalent and non-coherent sampling measurements“. ACTA IMEKO 6, Nr. 4 (28.12.2017): 54. http://dx.doi.org/10.21014/acta_imeko.v6i4.474.

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Estimations of the signal component parameters in the case of random equivalent time sampling and under non-coherent sampling condition comprise two main error contributions: spectral leakage effect due to non-coherency and additional noise due to the randomization of sampling intervals. In the estimation procedure the non-parametric interpolated DFT approach has to be used first to estimate the component frequency and, after that, an iterative 4-parametric sine-fit algorithm should be used for other component parameters (amplitude and phase). Their estimations are possible when the duty ratio of random samples from the total samples in the non-coherent measurement interval is above 0.1. With these duty ratios of random samples it is possible to achieve error levels of 0.001 bins of the frequency estimations in relation to the estimation on full ensemble of points.
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Roberts, Lyle E., Robert L. Ward, Craig Smith und Daniel A. Shaddock. „Coherent Beam Combining Using an Internally Sensed Optical Phased Array of Frequency-Offset Phase Locked Lasers“. Photonics 7, Nr. 4 (28.11.2020): 118. http://dx.doi.org/10.3390/photonics7040118.

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Coherent beam combining can be used to scale optical power and enable mechanism-free beam steering using an optical phased array. Coherently combining multiple free-running lasers in a leader-follower laser configuration is challenging due to the need to measure and stabilize large and highly dynamic phase differences between them. We present a scalable technique based on frequency-offset phase locking and digitally enhanced interferometry to clone the coherence of multiple lasers without the use of external sampling optics, which has the potential to support both coherent and spectral beam combining, and alleviates issues of voltage wrapping associated with actuating feedback control using electro-optic modulators. This technique was demonstrated experimentally using a tiled-aperture optical phased array in which the relative output phase of three free-running lasers was stabilized with an RMS output phase stability of λ/104.
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Tankeliun, Tomas, Oleg Zaytsev und Vytautas Urbanavicius. „Hybrid Time-Base Device for Coherent Sampling Oscilloscope“. Measurement Science Review 19, Nr. 3 (01.06.2019): 93–100. http://dx.doi.org/10.2478/msr-2019-0015.

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Abstract In this paper, a hybrid time-base (HTB) device for the coherent sampling oscilloscope is presented. The HTB device makes it possible to reduce the uncertainty of determining the time position of the sample in the horizontal channel of the sampling oscilloscope. For its functioning, the proposed HTB device requires that the system-under-test, in addition to the test signal, also has a synchronous reference clock – harmonic oscillation. It should be noted that both the test signal and the harmonic reference clock are sampled simultaneously. The harmonic reference clock is connected to one of the oscilloscope channels and a special algorithm processes the clock samples and adjusts the coherent sampling mode. Two techniques of determining the position of the sample on the time axis are combined in the HTB device – the “trigonometric”, when the position is calculated by the arccosine or arcsine formula of the reference clock sampling value, and the interpolation method, according to which the time position of the sample is found by averaging the positions of two adjacent samples, obtained using said “trigonometric” technique. Primary experimental studies have shown that using the HTB device can reduce jitter of the sampling oscilloscope by several times and the drift with constant time distortion components is practically absent in this device.
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Dissertationen zum Thema "Coherent sampling"

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Li, Changxiu [Verfasser]. „Femtosecond Yb:KYW oscillators based high-speed asynchronous optical sampling and coherent acoustic phonon investigations / Changxiu Li“. Konstanz : KOPS Universität Konstanz, 2020. http://d-nb.info/1215032706/34.

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河合, 勇太, Yuta KAWAI, 義之 辻, Yoshiyuki TSUJI, 豊. 久木田 und Yutaka KUKITA. „エッジトーン現象によって噴流中に形成された組織構造の特徴 (第１報, レイノルズ応力と乱れの生成項からの考察)“. 日本機械学会, 2006. http://hdl.handle.net/2237/9095.

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Symonds, Christopher Charles. „Development and applications of new basis set sampling and basis set handling procedures for the coupled coherent states family of methods“. Thesis, University of Leeds, 2015. http://etheses.whiterose.ac.uk/13430/.

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The Coupled Coherent States family of methods have shown themselves capable of simulating the quantum dynamics of many different systems. The ability of these methods to accurately describe quantum behaviour is dependent on using a basis set which covers a sufficient area of phase space. If the area covered is too small, the basis set will be unable to adequately describe the dynamics of the system, however if the area is too large and the basis functions become too widely spaced, coupling will be lost between the coherent states and the simulation will fall into the semiclassical regime. In some situations the loss of this coupling becomes accelerated, through trajectories guiding the basis functions far from each other in phase space for example, limiting the ability of these methods to accurately describe quantum behaviour. This thesis demonstrates two techniques for preserving a correct description of the wavefunction in phase space. Firstly a combination of initial sampling using swarms of basis function trains and basis function cloning during propagation of the wavefunction is shown to correct a disagreement seen between the two formulations of the Multi- Configurational Ehrenfest method when simulating the high dimensional spin boson model. This combination gives a good agreement with benchmark calculations found using the Multi-Configurational Time-Dependent Hartree method. The techniques used to correct this disagreement have been used previously for on-the-fly ab initio direct dynamics simulations, reported in references [1] and [2], and so this investigation provides validation for the results obtained in those publications. Secondly a system of adaptive reprojection of the wavefunction is shown to allow a large grid of coherent states to be reduced to only the area of interest, while keeping the basis set in that region. It is also demonstrated that this will still hold even if the equations of motion tend to move basis functions far away from this area. This adaptive reprojection technique is tested against the high harmonic generation of an electron bound to a pseudo-atomic potential in one dimension, yielding results which are in good agreement with benchmark calculations carried out using the Time-Dependent Schrodinger equation.
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Čepl, Ondřej. „Tlumení tlakových pulzací a snižování hluku v potrubních systémech“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2021. http://www.nusl.cz/ntk/nusl-444301.

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The diploma thesis deals with pressure pulsations in pipeline system with dynamic muffler. There is presented original geometry of side-branch resonator. Pressure pulsations are solved by a created mathematical model, numerical simulations and verified by an experimental approach. The influence of dynamic and bulk viscosity is involved in derived governing equations. A system of nonlinear equations is solved by genetic algorithm and frequency dependent relationship of bulk viscosity of air is determined afterwards. The correct function of used pressure sensors is tested. The processing of experimental data is performed by the fast Fourier transform with coherent sampling. Finally, a comparison of analytical, numerical and experimental approaches is introduced for different geometric variants of presented muffler.
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Ayari, Lotfi. „Contribution au développement d’un banc de mesures temporelles 4-canaux pour la caractérisation avancée de composants et de sous-systèmes RF non linéaires“. Thesis, Limoges, 2016. http://www.theses.fr/2016LIMO0117/document.

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Les communications futures pour les applications civiles et militaires utilisent des signaux modulés complexes large bande qui seront émis à travers des amplificateurs de puissance multivoie de type DOHERTY qui devront avoir des performances en puissance, rendement, OBO et largeur de bande qui constituent aujourd’hui un véritable défi à relever. Pour ce faire les concepteurs ont besoin d’outils de caractérisation temporelle permettant la mesure normalisées et l’optimisation des tensions et courants aux accès des dispositifs non linéaires sous pointes ou connectorisés. Ce travail de thèse a permis de mettre en œuvre cet outil de caractérisation temporelle qui a été utilisé pour répondre à des besoins spécifiques pour la modélisation de transistor, pour l’optimisation de leur fonctionnement en termes de stabilité impulsion à impulsion, pour la recherche des conditions optimales de leur fonctionnement dans un amplificateur de type Doherty. Pour cette mise en œuvre une modélisation mathématique des échantillonneurs a été réalisée pour évaluer leurs performances et choisir le mieux adapté à la mesure temporelle RF. Des procédures d’étalonnages rigoureuses ont été développées pour obtenir simultanément des formes d’ondes temporelles calibrées à spectre très large (Basse fréquences jusqu’aux Hyperfréquences)
The future communications for civil and military applications will use complex wideband modulated signals to be transmitted through multi-channel DOHERTY power amplifiers which should have high performance in terms of power, efficiency, OBO, and bandwidth. In order to meet these stringent requirements, designers need time-domain characterization tools for calibrated measurements and for optimizing voltages and currents at both ports of non-linear connectorized or on-wafer devices. This work successfully implements time-domain characterization tools used to meet specific needs for transistor modeling, to optimize their operation in terms of pulse to pulse stability, and to search optimal conditions of their operation modes in a Doherty power amplifier. For this implementation, mathematical modeling is performed to evaluate sampler’s performances in terms of time-domain sampling efficiency in order to choose the best suited sampling architecture for RF time-domain measurements. Rigorous calibration procedures have been developed to obtain simultaneously full time-domain calibrated waveforms (from low Frequencies to Microwave frequencies)
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Hamdi, Oussama. „Architecture d’échantillonnage rapide pour l’imagerie RADAR“. Thesis, Limoges, 2019. http://www.theses.fr/2019LIMO0120.

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Les systèmes Radar ULB utilisent des signaux dont le spectre dépasse une décade et se situe dans la bande 100MHz-10GHz. L’imagerie Radar ULB s’est beaucoup développée ces dernières années. Elle couvre un large champ applicatif : la défense, la sécurité civile, le biomédical. Elle permet en effet de pénétrer à travers les matériaux non conducteurs avec une résolution centimétrique. Dans les radars à impulsions ULB, la bande passante peut atteindre plusieurs GHz, de sorte qu'un Convertisseur Analogique-Numérique (CAN) pouvant échantillonner à cette vitesse avec une résolution de 10 à 14 bits est très difficile à concevoir. Il est toutefois possible de mesurer directement un signal Radar ULB reçu dans le domaine temporel en associant un CAN avec un T&HA avec une fréquence d’échantillonnage maximale de plusieurs GSa/s. Ces travaux portent sur le développement d’un démonstrateur Radar SAR ULB qui repose sur l’utilisation d’une technique de sous-échantillonnage cohérent pour la mesure des signaux Radar ULB. Ce démonstrateur Radar ULB est construit autour d’un CAN rapide (500 MS/s), d’un FPGA,et d’un T&HA ultra-large bande (5 GHz). Il permet ainsi la détection decibles en trois dimensions grâce à un algorithme de backpropagation
Typically, the waveforms transmitted by UWB radar cover a spectrum higher than a decade, in the 100MHz-10GHz frequency range. UWB Radar imaging has grown significantly in recent past years and is used for a large number of applications as defence, civil security and biomedical. One of their advantages lies in the fact that microwaves are able to penetrate through non-conductive materials with centimeter resolution. In UWB pulse radar, the bandwidth can reach several GHz, so that an Analog-to-Digital Converter (ADC) needs a high sampling rate and with a high resolution (>12 bits) to guarantee enough dynamic range. However, it is now possible to directly measure time-domain radar signal by associating an ADC with a Track and Hold Amplifier T&HA with wide RF bandwidth and with a maximum sampling frequency of several GSa/s. This work involves the development of a UWB SAR Radar demonstrator based on the use of a coherent sub-sampling technique for measuring UWB Radar signals. This UWB Radar demonstrator is built around a fast ADC (500 MS/s), an FPGA, and an ultra-wideband T&HA (5 GHz). It allows target detection by processing based on the use of a Radar image reconstruction algorithm
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Nguyen, Trung-Hiên. „Theoretical and experimental study of optical solutions for analog-to-digital conversion of high bit-rate signals“. Thesis, Rennes 1, 2015. http://www.theses.fr/2015REN1S110/document.

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Les formats de modulation bidimensionnels (i.e. basés sur l’amplitude et la phase de l’onde porteuse) ont gagné depuis peu le domaine des transmissions par fibre optique grâce aux progrès conjoints de l’électronique rapide et du traitement du signal, indispensables pour réaliser les récepteurs opto-électroniques utilisant la détection cohérente des signaux optiques. Pour pallier les limites actuelles en rapidité de commutation des circuits intégrés électroniques, une voie de recherche a été ouverte il y a quelques années, consistant à utiliser des technologies optiques pour faciliter la parallélisation du traitement du signal, notamment dans l’étape d’échantillonnage ultra-rapide du signal rendu possible par des horloges optiques très performantes. Le thème principal de cette thèse concerne l’étude théorique et expérimentale de la fonction de conversion analogique-numérique (ADC) de signaux optiques par un récepteur opto-électronique cohérent, associant les étapes d’échantillonnage optique linéaire, de conversion analogique-numérique et de traitement du signal. Un prototype, utilisant une solution originale pour la source d’échantillonnage, est modélisé, réalisé et caractérisé, permettant la reconstruction temporelle de signaux optiques modulés selon divers formats : NRZ, QPSK, 16-QAM. Les limitations optiques et électroniques du système sont analysées, notamment l’impact sur la reconstruction des signaux de divers paramètres : le taux d’extinction de la source optique, les paramètres de l’ADC (bande passante BW, temps d’intégration et nombre effectif de bits ENOB). Par ailleurs, de nouveaux algorithmes de traitement du signal sont proposés dans le cadre de la transmission optique cohérente à haut débit utilisant des formats de modulation bidimensionnels (amplitude et phase) : deux solutions sont proposées pour la compensation du déséquilibre de quadrature IQ dans les transmissions mono-porteuses: une méthode originale de l’estimation du maximum du rapport signal sur bruit ainsi qu’une nouvelle structure de compensation et d’égalisation conjointes; ces deux méthodes sont validées expérimentalement et numériquement avec un signal 16-QAM. Par ailleurs, une solution améliorée de récupération de porteuse (décalage de fréquence et estimation de la phase), basée sur une décomposition harmonique circulaire de la fonction de maximum de vraisemblance logarithmique, est validée numériquement pour la première fois dans le contexte des transmissions optiques (jusqu’à une modulation de 128-QAM). Enfin les outils développés dans ce travail ont finalement permis la démonstration d’une transmission sur 100 km d’un signal QPSK à 10 Gbaud fortement limité par un bruit de phase non linéaire et régénéré optiquement à l’aide d’un limiteur de puissance préservant la phase basé sur une nanocavité de cristal photonique
Bi-dimensional modulation formats based on amplitude and phase signal modulation, are now commonly used in optical communications thanks to breakthroughs in the field of electronic and digital signal processing (DSP) required in coherent optical receivers. Photonic solutions could compensate for nowadays limitations of electrical circuits bandwidth by facilitating the signal processing parallelization. Photonic is particularly interesting for signal sampling thanks to available stable optical clocks. The heart of the present work concerns analog-to-digital conversion (ADC) as a key element in coherent detection. A prototype of linear optical sampling using an original solution for the optical sampling source, is built and validated with the successful equivalent time reconstruction of NRZ, QPSK and 16-QAM signals. Some optical and electrical limitations of the system are experimentally and numerically analyzed, notably the extinction ratio of the optical source or the ADC parameters (bandwidth, integration time, effective number of bits ENOB). Moreover, some new DSPs tools are developed for optical transmission using bi-dimensional modulation formats (amplitude and phase). Two solutions are proposed for IQ quadrature imbalance compensation in single carrier optical coherent transmission: an original method of maximum signal-to-noise ratio estimation (MSEM) and a new structure for joint compensation and equalization; these methods are experimentally and numerically validated with 16-QAM signals. Moreover, an improved solution for carrier recovery (frequency offset and phase estimation) based on a circular harmonic expansion of a maximum loglikelihood function is studied for the first time in the context of optical telecommunications. This solution which can operate with any kind of bi-dimensional modulation format signal is numerically validated up to 128-QAM. All the DSP tools developed in this work are finally used in a demonstration of a 10 Gbaud QPSK 100 km transmission experiment, featuring a strong non-linear phase noise limitation and regenerated using a phase preserving and power limiting function based on a photonic crystal nanocavity
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Yaacoub, Tina. „Nouvelles approches pour l'estimation du canal ultra-large bande basées sur des techniques d'acquisition compressée appliquées aux signaux à taux d'innovation fini IR-UWB“. Thesis, Brest, 2017. http://www.theses.fr/2017BRES0077/document.

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La radio impulsionnelle UWB (IR-UWB) est une technologie de communication relativement récente, qui apporte une solution intéressante au problème de l’encombrement du spectre RF, et qui répond aux exigences de haut débit et localisation précise d’un nombre croissant d’applications, telles que les communications indoor, les réseaux de capteurs personnels et corporels, l’IoT, etc. Ses caractéristiques uniques sont obtenues par la transmission d’impulsions de très courte durée (inférieure à 1 ns), occupant une largeur de bande allant jusqu’à 7,5 GHz, et ayant une densité spectrale de puissance extrêmement faible (inférieure à -43 dBm/MHz). Les meilleures performances d’un système IR-UWB sont obtenues avec des récepteurs cohérents de type Rake, au prix d’une complexité accrue, due notamment à l’étape d’estimation du canal UWB, caractérisé par de nombreux trajets multiples. Cette étape de traitement nécessite l’estimation d’un ensemble de composantes spectrales du signal reçu, sans pouvoir faire appel aux techniques d’échantillonnage usuelles, en raison d’une limite de Nyquist particulièrement élevée (plusieurs GHz).Dans le cadre de cette thèse, nous proposons de nouvelles approches, à faible complexité, pour l’estimation du canal UWB, basées sur la représentation parcimonieuse du signal reçu, la théorie de l’acquisition compressée, et les méthodes de reconstruction des signaux à taux d’innovation fini. La réduction de complexité ainsi obtenue permet de diminuer de manière significative le coût d’implémentation du récepteur IR-UWB et sa consommation. D’abord, deux schémas d’échantillonnage compressé, monovoie (filtre SoS) et multivoie (MCMW) identifiés dans la littérature sont étendus au cas des signaux UWB ayant un spectre de type passe-bande, en tenant compte de leur implémentation réelle dans le circuit. Ces schémas permettent l’acquisition des coefficients spectraux du signal reçu et l’échantillonnage à des fréquences très réduites ne dépendant pas de la bande passante des signaux, mais seulement du nombre des trajets multiples du canal UWB. L’efficacité des approches proposées est démontrée au travers de deux applications : l’estimation du canal UWB pour un récepteur Rake cohérent à faible complexité, et la localisation précise en environnement intérieur dans un contexte d’aide à la dépendance.En outre, afin de réduire la complexité de l’approche multivoie en termes de nombre de voies nécessaires pour l’estimation du canal UWB, nous proposons une architecture à nombre de voies réduit, en augmentant le nombre d’impulsions pilotes émises.Cette même approche permet aussi la réduction de la fréquence d’échantillonnage associée au schéma MCMW. Un autre objectif important de la thèse est constitué par l’optimisation des performances des approches proposées. Ainsi, bien que l’acquisition des coefficients spectraux consécutifs permette une mise en oeuvre simple des schémas multivoie, nous montrons que les coefficients ainsi choisis, ne donnent pas les performances optimales des algorithmes de reconstruction. Ainsi, nous proposons une méthode basée sur la cohérence des matrices de mesure qui permet de trouver l’ensemble optimal des coefficients spectraux, ainsi qu’un ensemble sous-optimal contraint où les positions des coefficients spectraux sont structurées de façon à faciliter la conception du schéma MCMW. Enfin, les approches proposées dans le cadre de cette thèse sont validées expérimentalement à l’aide d’une plateforme expérimentale UWB du laboratoire Lab-STICC CNRS UMR 6285
Ultra-wideband impulse radio (IR-UWB) is a relatively new communication technology that provides an interesting solution to the problem of RF spectrum scarcity and meets the high data rate and precise localization requirements of an increasing number of applications, such as indoor communications, personal and body sensor networks, IoT, etc. Its unique characteristics are obtained by transmitting pulses of very short duration (less than 1 ns), occupying a bandwidth up to 7.5 GHz, and having an extremely low power spectral density (less than -43 dBm / MHz). The best performances of an IR-UWB system are obtained with Rake coherent receivers, at the expense of increased complexity, mainly due to the estimation of UWB channel, which is characterized by a large number of multipath components. This processing step requires the estimation of a set of spectral components for the received signal, without being able to adopt usual sampling techniques, because of the extremely high Nyquist limit (several GHz).In this thesis, we propose new low-complexity approaches for the UWB channel estimation, relying on the sparse representation of the received signal, the compressed sampling theory, and the reconstruction of the signals with finite rate of innovation. The complexity reduction thus obtained makes it possible to significantly reduce the IR-UWB receiver cost and consumption. First, two existent compressed sampling schemes, single-channel (SoS) and multi-channel (MCMW), are extended to the case of UWB signals having a bandpass spectrum, by taking into account realistic implementation constraints. These schemes allow the acquisition of the spectral coefficients of the received signal at very low sampling frequencies, which are not related anymore to the signal bandwidth, but only to the number of UWB channel multipath components. The efficiency of the proposed approaches is demonstrated through two applications: UWB channel estimation for low complexity coherent Rake receivers, and precise indoor localization for personal assistance and home care.Furthermore, in order to reduce the complexity of the MCMW approach in terms of the number of channels required for UWB channel estimation, we propose a reduced number of channel architecture by increasing the number of transmitted pilot pulses. The same approach is proven to be also useful for reducing the sampling frequency associated to the MCMW scheme.Another important objective of this thesis is the performance optimization for the proposed approaches. Although the acquisition of consecutive spectral coefficients allows a simple implementation of the MCMW scheme, we demonstrate that it not results in the best performance of the reconstruction algorithms. We then propose to rely on the coherence of the measurement matrix to find the optimal set of spectral coefficients maximizing the signal reconstruction performance, as well as a constrained suboptimal set, where the positions of the spectral coefficients are structured so as to facilitate the design of the MCMW scheme. Finally, the approaches proposed in this thesis are experimentally validated using the UWB equipment of Lab-STICC CNRS UMR 6285
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Shafiullah, Syed N. „On the role of correspondence noise in human visual motion perception. A systematic study on the role of correspondence noise affecting Dmax and Dmin, using random dot kinematograms: A psychophysical and modelling approach“. Thesis, University of Bradford, 2008. http://hdl.handle.net/10454/4280.

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One of the major goals of this thesis is to investigate the extent to which correspondence noise, (i.e., the false pairing of dots in adjacent frames) limits motion detection performance in random dot kinematograms (RDKs). The performance measures of interest are Dmax and Dmin i.e., the largest and smallest inter-frame dot displacement, respectively, for which motion can be reliably detected. Dmax and threshold coherence (i.e., the smallest proportion of dots that must be moved between frames for motion to be reliably detected) in RDKs are known to be affected by false pairing or correspondence noise. Here the roles of correspondence noise and receptive field geometry in limiting performance are investigated. The range of Dmax observed in the literature is consistent with the current information-limit based interpretation. Dmin is interpreted in the light of correspondence noise and under-sampling. Based on the psychophysical experiments performed in the early parts of the dissertation, a model for correspondence noise based on the principle of receptive field scaling is developed for Dmax. Model simulations provide a good account of psychophysically estimated Dmax over a range of stimulus parameters, showing that correspondence noise and receptive field geometry have a major influence on displacement thresholds.
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Shafiullah, Syed Nadeemullah. „On the role of correspondence noise in human visual motion perception : a systematic study on the role of correspondence noise affecting Dmax and Dmin, using random dot kinematograms : a psychophysical and modelling approach“. Thesis, University of Bradford, 2008. http://hdl.handle.net/10454/4280.

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One of the major goals of this thesis is to investigate the extent to which correspondence noise, (i.e., the false pairing of dots in adjacent frames) limits motion detection performance in random dot kinematograms (RDKs). The performance measures of interest are Dmax and Dmin i.e., the largest and smallest inter-frame dot displacement, respectively, for which motion can be reliably detected. Dmax and threshold coherence (i.e., the smallest proportion of dots that must be moved between frames for motion to be reliably detected) in RDKs are known to be affected by false pairing or correspondence noise. Here the roles of correspondence noise and receptive field geometry in limiting performance are investigated. The range of Dmax observed in the literature is consistent with the current information-limit based interpretation. Dmin is interpreted in the light of correspondence noise and under-sampling. Based on the psychophysical experiments performed in the early parts of the dissertation, a model for correspondence noise based on the principle of receptive field scaling is developed for Dmax. Model simulations provide a good account of psychophysically estimated Dmax over a range of stimulus parameters, showing that correspondence noise and receptive field geometry have a major influence on displacement thresholds.
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Buchteile zum Thema "Coherent sampling"

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Feichtinger, Hans G. „Coherent Frames and Irregular Sampling“. In Recent Advances in Fourier Analysis and Its Applications, 427–40. Dordrecht: Springer Netherlands, 1990. http://dx.doi.org/10.1007/978-94-009-0665-5_24.

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Yang, Jing, Yuan Ma, Tianyu Chen, Jingqiang Lin und Jiwu Jing. „Extracting More Entropy for TRNGs Based on Coherent Sampling“. In Lecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, 694–709. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-59608-2_38.

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Zhuang, Yuming, und Degang Chen. „Accurate Spectral Testing with Non-coherent Sampling for Multi-tone Test“. In Accurate and Robust Spectral Testing with Relaxed Instrumentation Requirements, 97–111. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-77718-4_6.

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Tardu, S. „Detection and Identification of Near-Wall Coherent Structures Through Conditional-Sampling“. In Fluid Mechanics and Its Applications, 355–64. Dordrecht: Springer Netherlands, 1999. http://dx.doi.org/10.1007/978-94-011-4601-2_31.

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Kadota, Akihiro, Iehisa Nezu und Koichi Suzuki. „Turbulence Measurements and Conditional Sampling Analysis on Coherent Vortices in Unsteady Open-Channel Flows over Dune Bed“. In IUTAM Symposium on Geometry and Statistics of Turbulence, 351–56. Dordrecht: Springer Netherlands, 2001. http://dx.doi.org/10.1007/978-94-015-9638-1_46.

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Gamon, John A., Ran Wang, Hamed Gholizadeh, Brian Zutta, Phil A. Townsend und Jeannine Cavender-Bares. „Consideration of Scale in Remote Sensing of Biodiversity“. In Remote Sensing of Plant Biodiversity, 425–47. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-33157-3_16.

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AbstractA coherent and effective remote sensing (RS) contribution to biodiversity monitoring requires careful consideration of scale in all its dimensions, including spatial, temporal, spectral, and angular, along with biodiversity at different levels of biological organization. Recent studies of the relationship between optical diversity (spectral diversity) and biodiversity reveal a scale dependence that can be influenced by the RS methods used, vegetation type, and degree and nature of disturbance. To better understand these issues, we call for multi-scale field campaigns that test the effect of sampling scale, vegetation type, and degree of disturbance on the ability to detect different kinds of biodiversity, along with the development of improved models that incorporate both physical and biological principles as well as ecological and evolutionary theory. One goal of these studies would be to more closely match instrumentation and sampling scales to biological definitions of biodiversity and so improve optical diversity (spectral diversity) as a proxy for biodiversity. The ultimate goal would be to design and implement a truly effective, “scale-aware” global biodiversity monitoring system employing RS methods. Such a system could improve our understanding of the distribution and functional importance of biodiversity and enhance our ability to manage ecosystems for resilience and sustainability in a changing world.
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Schulkin, Jay. „Coping and Sampling in Biological Machinery“. In Pragmatism and the Search for Coherence in Neuroscience, 87–111. London: Palgrave Macmillan UK, 2015. http://dx.doi.org/10.1057/9781137526731_5.

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Xu, Qing, Roberto Brunelli, Stefano Messelodi, Jiawan Zhang und Mingchu Li. „Image Coherence Based Adaptive Sampling for Image Synthesis“. In Computational Science and Its Applications – ICCSA 2004, 693–702. Berlin, Heidelberg: Springer Berlin Heidelberg, 2004. http://dx.doi.org/10.1007/978-3-540-24709-8_73.

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Sun, Yongqing, Kyoko Sudo, Yukinobu Taniguchi und Masashi Morimoto. „Sampling of Web Images with Dictionary Coherence for Cross-Domain Concept Detection“. In Lecture Notes in Computer Science, 283–92. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-35728-2_27.

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Zhuang, Yuming, und Degang Chen. „Accurate Spectral Testing with Arbitrary Non-coherency in Sampling and Simultaneous Drifts in Amplitude and Frequency“. In Accurate and Robust Spectral Testing with Relaxed Instrumentation Requirements, 33–57. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-77718-4_3.

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Konferenzberichte zum Thema "Coherent sampling"

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Qin Bo, Zhang Sheng, Quan Jinguo, H. F. Rashvand und Lin Xiaokang. „Nonuniform sampling in coherent UWB system“. In IET International Communication Conference on Wireless Mobile & Computing (CCWMC 2009). IET, 2009. http://dx.doi.org/10.1049/cp.2009.1913.

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Ramaswamy, Anand, Leif A. Johansson, Jonathan Klamkin, Darko Zibar, Larry A. Coldren, Mark J. Rodwell und John E. Bowers. „Optical Phase Demodulation of a 10GHz RF Signal using Optical Sampling“. In Coherent Optical Technologies and Applications. Washington, D.C.: OSA, 2008. http://dx.doi.org/10.1364/cota.2008.ctuc3.

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Coddington, Ian, William C. Swann und Nathan R. Newbury. „Frequency comb spectroscopy with coherent optical sampling“. In Fourier Transform Spectroscopy. Washington, D.C.: OSA, 2009. http://dx.doi.org/10.1364/fts.2009.fmb1.

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Chen, Xin, Inwoong Kim, Guifang Li, Hanyi Zhang und Bingkun Zhou. „Coherent Detection Using Optical Time-Domain Sampling“. In 2008 Conference on Optical Fiber Communication - OFC 2008 Collocated National Fiber Optic Engineers. IEEE, 2008. http://dx.doi.org/10.1109/ofc.2008.4528094.

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Valtcha, Boyan, Viktor Fischer und Alain Aubert. „Enhanced TRNG based on the coherent sampling“. In 2009 3rd International Conference on Signals, Circuits and Systems (SCS 2009). IEEE, 2009. http://dx.doi.org/10.1109/icscs.2009.5412601.

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Liu, Shuo, und Qiaoling Wang. „Adaptive Coherent Sampling for Network Delay Measurement“. In ICC 2020 - 2020 IEEE International Conference on Communications (ICC). IEEE, 2020. http://dx.doi.org/10.1109/icc40277.2020.9149155.

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Fischer, J. K., R. Ludwig, L. Molle, C. Schmidt-Langhorst, C. C. Leonhardt, A. Matiss und C. Schubert. „Digital coherent receiver based on parallel optical sampling“. In 2010 36th European Conference and Exhibition on Optical Communication - (ECOC 2010). IEEE, 2010. http://dx.doi.org/10.1109/ecoc.2010.5621503.

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Staal, Lasse, und Toshiya Hachisuka. „Randomized coherent sampling for reducing perceptual rendering error“. In ACM SIGGRAPH 2012 Posters. New York, New York, USA: ACM Press, 2012. http://dx.doi.org/10.1145/2342896.2343023.

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Hampson, G. „Relationships between wavefield sampling and coherent noise attenuation“. In 56th EAEG Meeting. European Association of Geoscientists & Engineers, 1994. http://dx.doi.org/10.3997/2214-4609.201409944.

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Chou, Hsu-Feng, Leif Johansson, Darko Zibar, Anand Ramaswamy, Mark Rodwell und John Bowers. „All-Optical Coherent Receiver with Feedback and Sampling“. In 2006 International Topical Meeting on Microwave Photonics. IEEE, 2006. http://dx.doi.org/10.1109/mwp.2006.346530.

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Berichte der Organisationen zum Thema "Coherent sampling"

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Maxwell, Timothy John. Measurement of Sub-Picosecond Electron Bunches via Electro-Optic Sampling of Coherent Transition Radiation. Office of Scientific and Technical Information (OSTI), Januar 2012. http://dx.doi.org/10.2172/1249490.

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Shearman, R. K., Jonathan D. Nash, James N. Moum und John A. Barth. Lateral Coherence and Mixing in the Coastal Ocean: Adaptive Sampling using Gliders. Fort Belvoir, VA: Defense Technical Information Center, September 2010. http://dx.doi.org/10.21236/ada542832.

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Shearman, R. K., Jonathan D. Nash, James N. Moum und John A. Barth. Lateral Coherence and Mixing in the Coastal Ocean: Adaptive Sampling using Gliders. Fort Belvoir, VA: Defense Technical Information Center, September 2011. http://dx.doi.org/10.21236/ada557113.

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McCarthy, Noel, Eileen Taylor, Martin Maiden, Alison Cody, Melissa Jansen van Rensburg, Margaret Varga, Sophie Hedges et al. Enhanced molecular-based (MLST/whole genome) surveillance and source attribution of Campylobacter infections in the UK. Food Standards Agency, Juli 2021. http://dx.doi.org/10.46756/sci.fsa.ksj135.

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This human campylobacteriosis sentinel surveillance project was based at two sites in Oxfordshire and North East England chosen (i) to be representative of the English population on the Office for National Statistics urban-rural classification and (ii) to provide continuity with genetic surveillance started in Oxfordshire in October 2003. Between October 2015 and September 2018 epidemiological questionnaires and genome sequencing of isolates from human cases was accompanied by sampling and genome sequencing of isolates from possible food animal sources. The principal aim was to estimate the contributions of the main sources of human infection and to identify any changes over time. An extension to the project focussed on antimicrobial resistance in study isolates and older archived isolates. These older isolates were from earlier years at the Oxfordshire site and the earliest available coherent set of isolates from the national archive at Public Health England (1997/8). The aim of this additional work was to analyse the emergence of the antimicrobial resistance that is now present among human isolates and to describe and compare antimicrobial resistance in recent food animal isolates. Having identified the presence of bias in population genetic attribution, and that this was not addressed in the published literature, this study developed an approach to adjust for bias in population genetic attribution, and an alternative approach to attribution using sentinel types. Using these approaches the study estimated that approximately 70% of Campylobacter jejuni and just under 50% of C. coli infection in our sample was linked to the chicken source and that this was relatively stable over time. Ruminants were identified as the second most common source for C. jejuni and the most common for C. coli where there was also some evidence for pig as a source although less common than ruminant or chicken. These genomic attributions of themselves make no inference on routes of transmission. However, those infected with isolates genetically typical of chicken origin were substantially more likely to have eaten chicken than those infected with ruminant types. Consumption of lamb’s liver was very strongly associated with infection by a strain genetically typical of a ruminant source. These findings support consumption of these foods as being important in the transmission of these infections and highlight a potentially important role for lamb’s liver consumption as a source of Campylobacter infection. Antimicrobial resistance was predicted from genomic data using a pipeline validated by Public Health England and using BIGSdb software. In C. jejuni this showed a nine-fold increase in resistance to fluoroquinolones from 1997 to 2018. Tetracycline resistance was also common, with higher initial resistance (1997) and less substantial change over time. Resistance to aminoglycosides or macrolides remained low in human cases across all time periods. Among C. jejuni food animal isolates, fluoroquinolone resistance was common among isolates from chicken and substantially less common among ruminants, ducks or pigs. Tetracycline resistance was common across chicken, duck and pig but lower among ruminant origin isolates. In C. coli resistance to all four antimicrobial classes rose from low levels in 1997. The fluoroquinolone rise appears to have levelled off earlier and among animals, levels are high in duck as well as chicken isolates, although based on small sample sizes, macrolide and aminoglycoside resistance, was substantially higher than for C. jejuni among humans and highest among pig origin isolates. Tetracycline resistance is high in isolates from pigs and the very small sample from ducks. Antibiotic use following diagnosis was relatively high (43.4%) among respondents in the human surveillance study. Moreover, it varied substantially across sites and was highest among non-elderly adults compared to older adults or children suggesting opportunities for improved antimicrobial stewardship. The study also found evidence for stable lineages over time across human and source animal species as well as some tighter genomic clusters that may represent outbreaks. The genomic dataset will allow extensive further work beyond the specific goals of the study. This has been made accessible on the web, with access supported by data visualisation tools.
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