Search results for " modulation"
showing 10 items of 496 documents
Performance of coded modulation employing differential encoding over Rayleigh fading channels
1999
Multilevel coding and bit-interleaved coded modulation employing differential encoding and non-coherent reception over flat fading channels are assessed. To achieve high bandwidth efficiencies mixed amplitude/phase modulation is performed. It is shown that multiple symbol detection only provides gains for multilevel coding as Gray labelling of the differential symbols is not possible.
First experimental demonstration of a plasmonic MMI switch in 10 Gb/s true data traffic conditions
2012
We report the first experimental performance evaluation of a 75 um long plasmonic MMI switch, hetero-integrated on a SOI platform, operating with 10Gb/s data signals. The switch exhibits 2.9μs response time and 44.5% modulation depth while its extinction ratio varies from 5.4 to -1.5 dB for 35mW switching power. Error-free performance was achieved.
Algebraic real-time algorithm for B-Spline sinusoidal pulse width modulation in three phase voltage source inverters.
2008
In this paper a novel algebraic real-time algorithm for implementation of sinusoidal pulse width modulation (SPWM) based on B-spline carriers is introduced and discussed. B-spline functions are used as carrier signals with the aim to to reduce harmonic content of the three phase inverter output voltage. This algorithm eliminates the problem of B-spline recursive evaluation with convolution integrals or convolution sums in digital counterpart. The pulse pattern synthesis is made with the help pre-calculated duty cycle expressions. In this way the carrier signals have not to be really synthesized, hence the hardware and the whole inverter control system becomes cheaper, more reliable and affo…
<title>Stereovision studies by disbalanced images</title>
2003
Studies are focused on design and appraisal of an objective test of the quality of stereovision depending on optical stimuli blurring and detecting of the stereovision threshold at various stimuli blur degree. The method is based on the principles of grayscale and color random dot stereotests. Experiments may be divided with respect to the principle of demonstration: 1) the blur is modeled by defocusing an optical lens - the strength of the optical system is varied at a constant quality of the stimulus, or 2) the blur is simulated on the computer screen - here the quality of the stimulus varies. To obtain an independent description and to measure blurring the experimentally demonstrated ima…
Architecture of a digital PFM controller for IC implementation
2006
This paper presents a digital controller architecture oriented to IC implementation. The classical digital pulse width modulator (D-PWM), using digital analog converter (DAC), is replaced with a Sigma-Delta (/spl Sigma//spl Delta/) modulator based on pulse frequency modulator (PFM) technique. Results of an investigation from a prototype for DC-DC converter, in terms of simulated and experimental performances, are reported, together with harmonic frequency investigation. The control function design is implemented on a field programmable gate array (FPGA). As a consequence of good agreement between simulated and experimental results, the proposed architecture realizes a digital control loop w…
On the Design of Probe Signals in Wireless Acoustic Sensor Networks Self-Positioning Algorithms
2018
A wireless acoustic sensor network comprises a distributed group of devices equipped with audio transducers. Typically, these devices can interoperate with each other using wireless links and perform collaborative audio signal processing. Ranging and self-positioning of the network nodes are examples of tasks that can be carried out collaboratively using acoustic signals. However, the environmental conditions can distort the emitted signals and complicate the ranging process. In this context, the selection of proper acoustic signals can facilitate the attainment of this goal and improve the localization accuracy. This letter deals with the design and evaluation of acoustic probe signals all…
Experimental Evaluation of the Performance of a Three-Phase Five-Level Cascaded H-Bridge Inverter by Means FPGA-Based Control Board for Grid Connecte…
2018
Over the last decades, plants devoted to the generation of green energy significantly increased their number, together with the demand of same electrical energy, also stored in battery systems. This fact produced the growth of energy conversion systems with advanced performances with respect to the traditional ones. In this circumstance, multilevel converters play a significant role for their great advantages in performances, flexibility, fault-tolerability, employment of renewable energy sources and storage systems and finally yet importantly reduced filter requirements. In this context, this paper faces the performance of a cascaded H-bridge 5 level inverter in terms of harmonic distortio…
Surface plasmon propagation in metal nanowires
2012
Plasmonic circuitry is considered as a promising solution-effectivetechnology for miniaturizing and integrating the next generation ofoptical nano-devices. The realization of a practical plasmonic circuitry strongly depends on the complete understanding of the propagation properties of two key elements: surface plasmons and electrons. The critical part constituting the plasmonic circuitry is a waveguide which can sustain the two information-carriers simultaneously. Therefore, we present in this thesis the investigations on the propagation of surface plasmons and the co-propagation of surface plasmons and electrons in single crystalline metal nanowires. This thesis is therefore divided into …
Pas de titre en anglais
2010
Within the quick nano-fabrication techniques evolution and the increasing needs in low space and energy opto-electronic functions on-chip integration, studies and control of electromagnetic resonances of sub-micrometric objects are crucial issues. One aim of this work was then to improve our knowledge of the light-matter interaction. To this end, optical near-field experiments and complementary numerical development of models have been performed to study electromagnetic resonances due to light-matter interaction in sub-micrometric resonators. As an introduction, the first part of the manuscript presents the main phenomena involved in near-field optical microscopy and the used SNOM operation…
Accessing finite momentum excitations of the one-dimensional Bose-Hubbard model using superlattice modulation spectroscopy
2018
We investigate the response to superlattice modulation of a bosonic quantum gas confined to arrays of tubes emulating the one-dimensional Bose-Hubbard model. We demonstrate, using both time-dependent density matrix renormalization group and linear response theory, that such a superlattice modulation gives access to the excitation spectrum of the Bose-Hubbard model at finite momenta. Deep in the Mott-insulator, the response is characterized by a narrow energy absorption peak at a frequency approximately corresponding to the onsite interaction strength between bosons. This spectroscopic technique thus allows for an accurate measurement of the effective value of the interaction strength. On th…