Apport de l'échantillonnage aléatoire à temps quantifié pour le traitement en bande de base dans un contexte radio logicielle restreinte

The work presented in this Ph.D. dissertation deals with the design of multistandard radio receivers that process signals with heterogeneous specifications. The originality of these research activities comes from the application of random sampling at the baseband stage of a software defined radio receiver. The purpose behind the choice of random sampling is to take advantage of its alias-free feature. The originality of this work is the analytic proof of the alias attenuation feature of the time quantized random sampling, the implementation version of the random sampling. A second contribution concerns also the analytic study of the simplest implementation version of the random sampling, the time quantized pseudo-random sampling (TQ-PRS). Theoretical formulas allow the estimation of the alias attenuation in terms of time quantization factor and oversampling ratio. Alias attenuation measurement permits to design the baseband stage of the proposed multistandard radio receiver architecture. The design concerns different configuration of the baseband stage according to the performances of the used analog-to-digital converters (ADC). The TQPRS allows decreasing the anti-aliasing filter order or the sampling frequency. The design of the baseband stage reveals a difference on the choice of the time quantization factor for each standard. The power consumption budget analysis demonstrates a power consumption gain of 30% regarding the power consumption of the analog baseband stage. This gain becomes 27.5% when the TQ-PRS clock and the digital canal selection stages are considered.Ces travaux de recherche s’inscrivent dans le cadre de la conception de récepteurs multistandard optimisés pouvant traiter des signaux à spécifications hétérogènes. L’idée est d’appliquer l’échantillonnage aléatoire au niveau de l’étage en bande de base d’un récepteur radio logicielle restreinte afin de tirer profit de son pouvoir d’anti-repliement. La nouveauté dans ces travaux est l’étude analytique de la réduction du repliement spectral par l’échantillonnage aléatoire à temps quantifié, candidat favorable à l’implémentation matérielle. Une deuxième contribution concerne aussi l’étude analytique de l’échantillonnage pseudo-aléatoire à temps quantifié (TQ-PRS) dont l’importance réside en sa grande facilité d’implémentation matérielle. Les formulations théoriques ont permis d’estimer l’atténuation des répliques en fonction du facteur de la quantification temporelle et du facteur du sur-échantillonnage. Les mesures de l’atténuation du repliement spectral ont permis de dimensionner l’étage en bande de base d’une architecture de réception multistandard. Le dimensionnement s’intéresse à différentes configurations de l’étage en bande de base régies par les performances du convertisseur analogique numérique (ADC) utilisé.Les travaux de recherche ont démontré que l’application du TQ-PRS au niveau de l’ADC mène soit à une réduction de l’ordre du filtre anti-repliement soit à une réduction de la fréquence d’échantillonnage. Un bilan global de la consommation de puissance a permis un gain de 30% de la consommation de l’étage en bande de base analogique. En tenant compte du générateur de l’horloge TQ-PRS et de l’étage de sélection numérique du canal, ce gain devient 25%

Contribution of the time-quantized random sampling technique applied to the base-band stage of software defined radio receivers

Ces travaux de recherche s’inscrivent dans le cadre de la conception de récepteurs multistandard optimisés pouvant traiter des signaux à spécifications hétérogènes. L’idée est d’appliquer l’échantillonnage aléatoire au niveau de l’étage en bande de base d’un récepteur radio logicielle restreinte afin de tirer profit de son pouvoir d’anti-repliement. La nouveauté dans ces travaux est l’étude analytique de la réduction du repliement spectral par l’échantillonnage aléatoire à temps quantifié, candidat favorable à l’implémentation matérielle. Une deuxième contribution concerne aussi l’étude analytique de l’échantillonnage pseudo-aléatoire à temps quantifié (TQ-PRS) dont l’importance réside en sa grande facilité d’implémentation matérielle. Les formulations théoriques ont permis d’estimer l’atténuation des répliques en fonction du facteur de la quantification temporelle et du facteur du sur-échantillonnage. Les mesures de l’atténuation du repliement spectral ont permis de dimensionner l’étage en bande de base d’une architecture de réception multistandard. Le dimensionnement s’intéresse à différentes configurations de l’étage en bande de base régies par les performances du convertisseur analogique numérique (ADC) utilisé.Les travaux de recherche ont démontré que l’application du TQ-PRS au niveau de l’ADC mène soit à une réduction de l’ordre du filtre anti-repliement soit à une réduction de la fréquence d’échantillonnage. Un bilan global de la consommation de puissance a permis un gain de 30% de la consommation de l’étage en bande de base analogique. En tenant compte du générateur de l’horloge TQ-PRS et de l’étage de sélection numérique du canal, ce gain devient 25%.The work presented in this Ph.D. dissertation deals with the design of multistandard radio receivers that process signals with heterogeneous specifications. The originality of these research activities comes from the application of random sampling at the baseband stage of a software defined radio receiver. The purpose behind the choice of random sampling is to take advantage of its alias-free feature. The originality of this work is the analytic proof of the alias attenuation feature of the time quantized random sampling, the implementation version of the random sampling. A second contribution concerns also the analytic study of the simplest implementation version of the random sampling, the time quantized pseudo-random sampling (TQ-PRS). Theoretical formulas allow the estimation of the alias attenuation in terms of time quantization factor and oversampling ratio. Alias attenuation measurement permits to design the baseband stage of the proposed multistandard radio receiver architecture. The design concerns different configuration of the baseband stage according to the performances of the used analog-to-digital converters (ADC). The TQPRS allows decreasing the anti-aliasing filter order or the sampling frequency. The design of the baseband stage reveals a difference on the choice of the time quantization factor for each standard. The power consumption budget analysis demonstrates a power consumption gain of 30% regarding the power consumption of the analog baseband stage. This gain becomes 27.5% when the TQ-PRS clock and the digital canal selection stages are considered

Supramolecular architectures of mononuclear nickel(II) and homobinuclear copper(II) complexes square with the 5,5'dimethyl-2,2'-bipyridine ligand: Syntheses, Crystal structures and Hirshfeld surface analyses

International audienceTwo new compounds based on one mononuclear nickel(II) and one homobinuclear copper(II) complexes respectively and of genrela formula [Ni(dmbpy)2(CH3COO)]ClO4 (1) and [Cu2(dmbpy)4(CH3COO)3]ClO4 (2) with dmbpy = 5,5'-dimethyl-2,2'bipyridine, were synthesized by hydrothermal treatment. Both were influenced by the coordinated acetate ion molecule. The crystal and molecular structures of (1) and (2) were determined by single crystal X-ray diffraction method and both compounds were additionnally characterized by means of elemental and thermogravimetric analysis, FT-IR spectroscopy, powder X-ray diffraction and UV-visible. The mononuclear complex (1) shows a distorted octahedral geometry around the metal ion. On the other hand, the copper(II) compound crystallizes as an homobinuclear system, in which each of the metal ions is located into the N2O3 coordination spheres adopting a distorted square pyramidal geometry. In (2) the intramolecular distance between two copper atoms is of the order of Cu1-Cu2 = 3.38 (2) Å. In both crystal packing of these two complexes, H-bonding,π⋯π, and C-H⋯π interactions are operative in forming supramolecular motifs. Complex (1) displays two 1-D chains that lead to form R 8 8 (42) ring motifs, repetition of which generates a 2-D supramolecular network. These chains interacts with the neighbouring ones via intermolecular C-H•••π and π•••π stacking interactions, leading to the formation of a 3D-stacking network (2-D+1-D→3-D). Formation of a 2-D supramolecular sheet in the solid state structure of (2) is facilitated by the C-H⋯O, C-H⋯π and π⋯π interactions (1-D+1-D→2-D). Hirshfeld surface analysis and theoretical calculations were carried out on the two compounds. The results clearly show that C-H•••O, C-H••• π and π•••π stacking interactions play a paramount role in the stabilization of the supramolecular architecture of (1) and (2). In addition, adsorption spectra reveal their semiconductive nature (4.19 eV for 1• and 4.43 eV for 2)

Contribution of major polyphenols to the antioxidant profile and cytotoxic activity of olive leaves

Aims: This study was designed to investigate the phytochemical profile and the cytotoxic activities of the eco-friendly extracts of olive leaves from Chemlali cultivar. Materials and Methods: The Phenolic composition of olive leaves extracts, the antioxidant activity and the cytotoxic effects against MCF-7 and HepG2 cells were determined. Results: Olive leaves extracts showed relevant total polyphenols contents. Oleuropein was the major detected phenolic compound reaching a concentration of 16.9 mg/ml. The antioxidant potential of the studied extracts varied from 23.7 to 46.5mM Trolox equivalents as revealed by DPPH and ABTS assays. Cytotoxicity experiments showed similar trends for both HepG2 and MCF-7 cells with the infusion extract being the most active. Conclusion: This study denotes that olive leaves may have great potential as endless bioresource of valuable bioactive compounds which may have a wide application. - 2019 Bentham Science Publishers.This work was supported by the Tunisian Ministery of Higher Education and Scientific Research under the contract program for Laboratory of Environmental Bioprocesses at Centre of Biotechnology of Sfax. This work was also partially supported by the JICA/JST Science and Technology Research Partnership for Sustainable Development (SATREPS) Project (A6A24087): �Valorization of Bio-resources in Semi-arid and Arid Land for Regional Development''.Scopu

Level-Crossing ADC Design and Evaluation Methodology for Normal and Pathological Electrocardiogram Signals Measurement

International audienceIn this paper, the level-crossing analog-to-digital converter (LC-ADC) is employed for electrocardiogram signals measurement. A biosignal-dependent design methodology for the LC-ADC is proposed to avoid distortion, caused by slope changes, leading to an 8-bit LC-ADC topology with a 10-kHz and 12-bit time counter. To evaluate the proposed design, the LC-ADC is modeled then evaluated regarding systematic time-quantization error and analog components’ non-idealities. A total number of 75 real electrocardiogram records from Physionet database with different waveforms and pathologies are used. LC-ADC evaluation results for time-quantization error show that 100% of the reconstructed signals have a signal-to-distortion ratio higher than 21 dB, which is the value of good quality. The evaluation of comparators’ offset voltage impact is analyzed with different ranges of the signal-to-distortion ratio showing the robustness of the proposed design methodology. Internal digital-to-analog converters (DACs) non-linearity impacts are evaluated showing only 1-dB degradation for signal distortion

Towards Time-Quantized Pseudo-Random Sampling for Green Communication

International audienc

Synthesis, crystal structure, and vibrational and DFT simulation studies of benzylammonium dihydrogen phosphite

Single crystals of a new organophosphite compound, C7H12NPO3, were grown by the slow evaporation technique and characterized by X-ray diffraction, IR absorption spectroscopy, Raman scattering spectroscopy, UV-visible spectroscopy, photoluminescence measurements, and thermal analysis. This salt crystallizes at 120 K in orthorhombic symmetry with space group Pbca and cell parameters a = 14.0377 (12) Å, b = 8.0915 (7) Å, and c = 16.2980 (2) Å. The same symmetry, Pbca, is shown by X-ray diffraction at 298 and 350 K. To minimize the thermal effects, the crystal structure determined at 120 K was used as the reference. In the crystal structure, the phosphite anions, H2PO3−, are connected to the organic cations, C6H5CH2NH3+, through N–H...O hydrogen bonds that form infinite parallel two-dimensional planes. Theoretical calculations were performed with density functional theory at the B3LYP/6-31G (d,p) level of theory to study the molecular structure and vibrational spectra of C7H12NPO3. The optimized geometry and the calculated frequencies are in good agreement with the experimental data. The UV-visible spectrum shows characteristic absorption bands in the region from 300 to 800 nm, which suggests that C7H12NPO3 is potentially suitable for optical applications. The absence of absorption in the visible region might enable achievement of microscopic nonlinear optical response with nonzero values. In addition, photoluminescence measurements showed that this compound exhibits green emission at 502 nm at room temperature