Search results for "Signal processing"
showing 10 items of 2451 documents
Advanced Optical Processing of Microwave Signals
2005
The authors present a review on the recent approaches proposed to implement transversal RF filters. Different tunable transversal filters consisting of wavelength tunable optical taps and those employing the tunability of dispersive devices are presented showing their high-performance characteristics. A comprehensive review of the fundamentals and a discussion on the main limitation of these structures are also included.
Design of double-tapered fibers for tailoring the acousto-optic spectral response
2016
A model to shape the spectral response of acousto-optic devices based on tapered fibers is reported. A double-tapered structure was designed in order to obtain a flat attenuation response with 34 nm bandwidth.
Design of a continuously tunable delay line using vectorial modulational instability and chromatic dispersion in optical fibers
2009
International audience; We design an all-optical tunable delay line based on both dispersive and wavelength conversion stages involving modulational instability of a two-frequency pump field propagating in a highly birefringent fiber. More precisely, we numerically show that, by varying the frequency separation between the two orthogonally polarized pump waves, we achieve a controllable and continuous delay of hundreds of picoseconds for signal pulse durations from picoseconds to nanoseconds, without pulse distortion and with only small peak power fluctuations. The proposed method does not require any tunable bandpass filter and can be applied to delay digital data streams at tens of Gbit/s…
High-speed and high-resolution interrogation of FBG sensors using wavelength-to-time mapping and Gaussian filters
2019
In this work we report a novel intensity-based technique for simultaneous high-speed and high-resolution interrogation of fiber Bragg grating (FBG) sensors. The method uses a couple of intensity Gaussian filters and the dispersion-induced wavelength-to-time mapping effect. The Bragg wavelength is retrieved by means of the amplitude comparison between the two filtered grating spectrums, which are mapped into a time-domain waveform. In this way, measurement distortions arising from residual power due to the grating sidelobes are completely avoided, and the wavelength measurement range is considerably extended with respect to the previously proposed schemes. We present the mathematical backgro…
Simultaneous remote extraction of multiple speech sources and heart beats from secondary speckles pattern
2009
The ability of dynamic extraction of remote sounds is very appealing. In this manuscript we propose an optical approach allowing the extraction and the separation of remote sound sources. The approach is very modular and it does not apply any constraints regarding the relative position of the sound sources and the detection device. The optical setup doing the detection is very simple and versatile. The principle is to observe the movement of the secondary speckle patterns that are generated on top of the target when it is illuminated by a spot of laser beam. Proper adaption of the imaging optics allows following the temporal trajectories of those speckles and extracting the sound signals ou…
Scene-based spectral calibration assessment of high spectral resolution imaging spectrometers
2009
An accurate knowledge of the spectral calibration of imaging spectrometers is required for optimum data processing and interpretation. The scene-based spectral characterization of imaging spectrometers is frequently necessary to update or replace the pre-flight laboratory-based spectral characterization supplied by the data provider. An automatic method for the estimation of spectral calibration parameters (channel position and bandwidth) at atmospheric absorption regions from high spectral resolution imaging spectrometers (spectral sampling interval below 5 nm) is presented in this contribution. The method has been tested on two commercial instruments with spectral sampling intervals below…
FDTD analysis of E-sectoral horn antennas for broad-band applications
1997
The finite-difference time-domain (FDTD) method is applied to study the performance of E-plane sectoral horn antennas designed for broad-band applications. These antennas (proposed for 6-18 GHz phased arrays) have a large bandwidth, and they are easily array integrated. These antennas have a highly complicated geometry that is modeled using a polygonal approximation in the curved boundaries. Perfect matched layers (PMLs) combined with first-order absorbing boundaries are employed to simulate the free-space environment in the FDTD mesh.
The absorption of light energy in flat fluidized photoreactors
1990
Abstract A flat fluidized bed with transparent walls is an ideal reactor for gas-solid photocatalytic or photoassisted reactions. This paper presents the relati
Automatic EMI filter design for power electronic converters oriented to high power density
2018
In this paper, a complete computer aided procedure based on the power density concept and aimed at the automatic design of EMI filters for power electronic converters is presented. It is rule-based, and it uses suitable databases built-up by considering information on passive components available from commercial datasheets. The power density constraint is taken into consideration by imposing the minimization of the filter volume and/or weight; nevertheless, the system in which the automatically designed filter is included satisfies the electromagnetic compatibility standards limits. Experimental validations of the proposed procedure are presented for two real case studies, for which the per…
Simplified analytical solution for the optimal design of Tuned Mass Damper Inerter for base isolated structures
2019
Abstract In this paper the use of the Tuned Mass Damper Inerter (TMDI) to control the response of base isolated structures under stochastic horizontal base acceleration is examined. Notably, the TMDI, recently introduced as a generalization of the classical Tuned Mass Damper, allows to achieve enhanced performance compared to the other passive vibration control devices. Thus, it represents an ideal alternative for reducing displacements of base isolated structures. To this aim, firstly a straightforward numerical approach is developed for the optimal design of this device considering a white noise base excitation. Further, a simplified analytical solution for the optimal design of TMDI para…