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Back, Antoine. "Conception et intégration d'un convertisseur analogique-paramètres flexible pour les capteurs intelligents". Electronic Thesis or Diss., Institut polytechnique de Paris, 2022. http://www.theses.fr/2022IPPAT020.
Pełny tekst źródłaThe Internet of Things (IoT) is currently experiencing huge developments. IoT includes lots of different devices such as Wireless Sensors Networks (WSN) or wearable electronics that rely on wireless communications. These networks need to understand the context in which they are used. This mean that the system must know what is happening around it, i.e. sense the environment, and understands the needs of the user. This requires always-on sensing on many sensors while being small, cheap, reliable and having a lifetime of several years. Analog-to-Feature (A2F) conversion is a new acquisition method that was thought for IoT devices. The converter aims at extracting useful features directly on the analog signal. By carefully choosing a set of features, it is possible to acquire only the relevant information for a given task. The proposed converter is based on the Non-Uniform Wavelet Sampling (NUWS) architecture. The architecture mixes the analog signal with tunable wavelets prior to integration and digital conversion. The aim of the thesis is to propose a method to design a generic A2F converter based on the NUWS. It includes the definition of the wavelet parameters in order to acquire a broad range of low frequency signals (ECG, EMG, EEG, speech …). This step requires the use of feature selection algorithms and machine learning algorithms for selecting the best set of wavelets for a given application and should be used to define the specifications for the converter. The feature selection step must be aware of physical implementation constraints to optimize energy consumption as much as possible. A feature selection algorithm is proposed to choose wavelets for a given application, in order to maximize classification accuracy while decreasing power consumption, through a power model designed in CMOS 0.18μm
Ben, Romdhane Manel. "Echantillonnage non uniforme appliqué à la numérisation des signaux radio multistandard". Paris, ENST, 2009. https://pastel.hal.science/pastel-00004780.
Pełny tekst źródłaResearch activities of this Doctorate thesis deal with the design of innovative circuits for multistandard signals digitalization. The originality of this research work comes from the use for the first time of Non Uniform Sampling (NUS) techniques for radio systems design and implementation. Presented research innovation is relative to the establishment of analytical formulations for NUS technique performance evaluation metrics to design a novel multistandard radio receiver topology with an Analog-to-Digital Converter (ADC) controlled by a non uniform clock. Results of this study have led to the synthesis of a single anti-aliasing filter for GSM/UMTS/WiFi standards and the reduction of ADC mean sampling frequency that allows the ADC power consumption reduction and the elimination of the Automatic Gain Control (AGC) circuit. The analytical study and the system level design have been completed by the proposal of an original digital architecture for a Pseudorandom Signal Sampler (PSS) circuit designed to overcome previous non uniform generators constraints. This PSS circuit experimental validation have been first achieved thanks to a preliminarily FPGA-based implementation then by a VLSI circuit design on 65 nm Digital CMOS technology. The PSS implementation results lead, for a time quantizer factor of 16, to a 470 (μm)² active area occupation, mean sampling frequencies reaching 200 MHz based on frequency synthesiser offering frequencies until 3. 2 GHz and finally a power consumption from 1. 45 to 290. 4 μW for mean sampling frequencies ranging from 1 MHz to 200 MHz. An experimental validation of proposed digitalization stage have been achieved thanks to the development of a test setup composed by the PSS generator delivering ADC control clock signals. A test sine wave is applied to the ADC input and its output is processed by a PC-based software created for sampled data processing. Obtained experimental results confirmed theoretical results in terms of ADC power consumption reduction
Traore, Samba. "Contribution à l'étude de l'échantillonnage non uniforme dans le domaine de la radio intelligente". Thesis, CentraleSupélec, 2015. http://www.theses.fr/2015SUPL0023/document.
Pełny tekst źródłaIn this work we consider the problem of designing an effective sampling scheme for sparse multi-band signals. Based on previous results on periodic non-uniform sampling (Multi-Coset) and using the well known Non-Uniform Fourier Transform through Bartlett’s method for Power Spectral Density estimation, we propose a new sampling scheme named the Dynamic Single Branch Non-uniform Sampler (DSB-NUS). The idea of the proposed scheme is to reduce the average sampling frequency, the number of samples collected, and consequently the power consumption of the Analog to Digital Converter (ADC). In addition to that our proposed method detects the location of the bands in order to adapt the sampling rate. In this thesis, we show through simulation results that compared to existing multi-coset based samplers, our proposed sampler provides superior performance, both in terms of sampling rate and energy consumption. It is notconstrained by the inflexibility of hardware circuitry and is easily reconfigurable. We also show the effect of the false detection of active bands on the average sampling rate of our new adaptive non-uniform sub-Nyquist sampler scheme
Bouchain, Antoine. "Estimation spectrale parcimonieuse de signaux à échantillonnage irrégulier : application à l’analyse vibratoire d’aubes de turbomachines à partir de signaux tip-timing". Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLC029.
Pełny tekst źródłaAs part of the certification of its helicopter engines, Safran Helicopter Engines performs operational tests in which the vibrations responses of turbomachines (compressors and turbines) are measured. The vibratory responses contain modes (or spectral lines) whose frequencies and amplitudes must be characterized. The measurements are provided by the tip-timing technology which can observe the vibrations of all the blades while rotating.However, tip-timing technology has two important features. Firstly, the sampling of the vibrating signals is irregular quasi-periodic. Secondly, the vibrating frequencies are generally higher than the equivalent sampling frequency. These two characteristics generate frequency components artefacts onto the vibrating signals spectrum. As a consequence, they strongly hinder the identification of the spectral content and thus disturb the interpretation of the blades vibratory behaviour.The proposed new spectral analysis method relies on sparse modelling of the tip-timing signals and considers the variations of the rotational frequency. The spectral analysis of the signals is then performed by the minimization of a linear least squares criterion regularized by a penalty of "norm-l0" by the Block-OMP algorithm.Using numerical results from synthetic signals, it is shown that this method provides good spectral component estimation performances and achieves a significant reduction of their artefacts. Considering the variations of the rotational frequency allows to take advantage of the use of long observation periods in order to significantly reduce the frequency components artefacts contained in the spectrum. In addition, with slightly better performances than the ESMV (acknowledged method for the tip-timing signals spectral analysis), the proposed method is about a hundred times faster.Two cases of real data are studied. Through a detection of a blade crack, the first studied case shows that the proposed method is relevant and makes equivalent estimates with respect to industrial methods. The second studied case presents several simultaneous synchronous and asynchronous vibrations. That highlights the ability to reduce the frequency components artefacts of the developed method in order to simplify the interpretation of the complex vibratory content of this signal.The optimization of the positioning of the tip-timing probes is also studied in order to simplify the identification of synchronous components. From numerical results, it is demonstrated that moving away the probes improves the amplitudes estimation of this type of components
Bouclon, Julien. "Spectrométrie de masse FT-ICR bidimensionnelle, développements et applications". Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLEE002/document.
Pełny tekst źródłaMass spectrometry provides two kinds of information: the molecular mass of molecules present in a mixture, obtained all at once (MS), and structure through isolation and fragmentation, obtained one by one (MS/MS). Two-dimensional FT-ICR MS allows simultaneous parallel acquisition of structural information without isolation, regardless of the number of molecules. Nevertheless, the low resolution in the indirect dimension, which could be improved by increasing the acquisition time, seemed to limit this method to a simple curiosity. The first objective is to implement non-uniform-sampling (NUS) in 2D FT-ICR MS. This method consist in the random acquisition of the same number of points in the indirect dimension as in uniform acquisition, but over a wider t1max range. Processing algorithms then reconstruct skipped points, and the result is an increase of signal resolution without wasting analysis time. The first step is to create an algorithm that can generate random sampling with a uniform distribution for an optimal coverage of the t1max range. Processing algorithms may have trouble to reconstruct small peaks when the number of skipped points increases. The second step is to choose the under-sampling ratio for the best compromise between the gain in resolution and the signal-to-noise ratio. The third and last step is to obtain MS/MS spectra with corrects isotopic patterns for fragments produced from heavy isotopes. The second objective is to improve the understanding of ion motions in ICR cells depending on the RF pulses by using Lorentz equations. The first goal is to determine the equations governing precursors motions until their detection. Then the fragmentation will be introduced and analytical solutions describing fragments motions will be established. The last step is to simulate the trajectories of precursors throughout the entire pulse sequence as well as the behavior of fragments clouds, from their formation to detection
Albert, Mélisande. "Tests d’indépendance par bootstrap et permutation : étude asymptotique et non-asymptotique. Application en neurosciences". Thesis, Nice, 2015. http://www.theses.fr/2015NICE4079/document.
Pełny tekst źródłaOn the one hand, we construct such tests based on bootstrap and permutation approaches. Their asymptotic performance are studied in a point process framework through the analysis of the asymptotic behavior of the conditional distributions of both bootstrapped and permuted test statistics, under the null hypothesis as well as under any alternative. A simulation study is performed verifying the usability of these tests in practice, and comparing them to existing classical methods in Neuroscience. We then focus on the permutation tests, well known for their non-asymptotic level properties. Their p-values, based on the delayed coincidence count, are implemented in a multiple testing procedure, called Permutation Unitary Events method, to detect the synchronization occurrences between two neurons. The practical validity of the method is verified on a simulation study before being applied on real data. On the other hand, the non-asymptotic performances of the permutation tests are studied in terms of uniform separation rates. A new aggregated procedure based on a wavelet thresholding method is developed in the density framework. Based on Talagrand's fundamental inequalities, we provide a new Bernstein-type concentration inequality for randomly permuted sums. In particular, it allows us to upper bound the uniform separation rate of the aggregated procedure over weak Besov spaces and deduce that this procedure seems to be optimal and adaptive in the minimax sens