The development of new advanced functionalities, miniaturization, and the aim of obtaining optimized performance in electronic devices significantly impacts their electromagnetic compatibility (EMC). ...As electronic components become more densely packed on a printed circuit board (PCB), unintended coupling between components can cause electromagnetic interference (EMI). These requirements result in design restrictions that make using a board level shield (BLS) essential in reducing intra-system EMI in PCB designs. This contribution focuses on studying and characterizing a BLS solution based on combining a noise suppression sheet (NSS) with an aluminum layer to reduce intra-system EMI coupling. This hybrid solution has the advantage of providing a shielding option that does not require any electronic redesign. It does not need a footprint or a ground connection as it can be affixed over the EMI source. The solution is expected to provide higher attenuation levels than using only an NSS by combining the absorbing properties of the magnetic material and the loss mechanism of the metal. In order to verify the effectiveness of the hybrid BLS proposed solution, the magnetic near-field emissions of an EMI source are analyzed in this study. The experimental measurements and simulated results demonstrate a significant increase (51.6 dB at 1 GHz) in the shielding effectiveness (SE) provided by the proposed solution compared to a conventional NSS.
The ideal procedure to start designing an electronic device is to consider the electromagnetic compatibility (EMC) from the beginning. Even so, EMC problems can appear afterward, especially when the ...designed system is interconnected with external devices. Thereby, electromagnetic interferences (EMIs) could be transmitted to our device from power cables that interconnect it with an external power source or are connected to another system to establish wired communication. The application of an EMI suppressor such as a sleeve core that encircles the cables is a widely used technique to attenuate EM disturbances. This contribution is focused on the characterization of a variation of this cable filtering solution based on openable core clamp or snap ferrites. This component is manufactured by two split parts pressed together by a snap-on mechanism which turns this into a quick, easy to install solution for reducing post-cable assembly EMI problems. The performance of three different materials, including two polycrystalline (MnZn and NiZn) materials and nanocrystalline (NC) solution, are analyzed in terms of effectiveness when the solid sleeve cores are split. The possibility of splitting an NC core implies an innovative technique due to the brittleness of this material. Thus, the results obtained from this research make it possible to evaluate this sample’s effectiveness compared to the polycrystalline ones. This characterization is carried out by the introduction of different gaps between the different split-cores and analyzing their behavior in terms of relative permeability and impedance. The results obtained experimentally are corroborated with the results obtained by a finite element method (FEM) simulation model with the aim of determining the performance of each material when it is used as an openable core clamp.
The interconnection of different electronic devices or systems through cables is becoming more difficult due to the hard restrictions related to electromagnetic compatibility (EMC) in order to comply ...with requirements. Therefore, the use of EMC components is a good solution to manage the problems associated with the filtering of electromagnetic interference (EMI) in cables and to pass the compliance test. In this sense, sleeve ferrite cores become a very interesting solution since they can be set around a wire and, hence, they provide an effective solution against EMI without having to redesign the electronic circuit. This contribution is focused on the characterization of the performance of a sleeve ferrite core based on a novel nanocrystalline (NC) novel material for EMI suppression and comparing it to the most conventional ceramic ferrite cores such as MnZn and NiZn. The research highlights the suitability of an NC novel component in terms of its magnetic properties to reduce EMI within the conducted emissions range. This range is generally defined by the International Special Committee on Radio Interference (CISPR) test standards frequency band that covers from 150 kHz up to 30 MHz (108 MHz in the case of CISPR 25). First, this study presents a description of the main parameters that define the behavior of NC and ceramic cores and, secondly, by analyzing the data obtained from experimental procedures, it is possible to directly determine the insertion loss parameter. Hence, this characterization procedure is used to obtain the performance of NC material compared to the conventional sleeve ferrite core compositions employed to filter the interferences in this problematic frequency range. As can be deduced from the results obtained, an NC sleeve ferrite core provides the best performance in terms of EMI filtering within a significant frequency range between 100 kHz and 100 MHz.
We propose and demonstrate experimentally a Time Gating technique for coherent optical encoding and decoding systems adding a reference pulse multiplexed in time to the encoded sequence. Receiver ...employs a differential detector that removes the undesired signal out the reference pulse.
We have tested experimentally the use of low cost DFB pulsed sources with narrow spectral bandwidth for all optical en/decoding based in Direct Sequences coherent technique and employing SSFBG which ...can be considered like a low cost alternative for header generation and recognition in PLS networks. The working principle was proven employing 20 ps pulses and SSFBGs designed with chip rates of 104 and 174 Gchips/s, obtaining an ACP versus XC ratios of 9 and 7 respectively.
We report the possibility to reduce the polarization-dependent loss (PDL) and the differential group delay (DGD) in fiber Bragg gratings (FBGs) by inducing polarization-mode coupling (PMC). To induce ...the PMC, the fiber is twisted before the inscription and then relaxed once the FBG is written. The theoretical concept as well as the simulation method used to study FBGs exhibiting PMC is detailed. The obtained results point out a significant decrease of the gratings' PDL and DGD values. In addition, experimental results, in good agreement with the theory, demonstrate the possibility to implement this method in practice.
We report two approaches for a high-resolution, position sensitive, gamma ray detector, based on solid estate photosensors and scintillation crystals. Scintillation photons are detected with a ...custom-made array of 144 SiPMs (12×12) covering an area of 5×5cm 2 . Individual SiPM signals are processed with 3 multiplexing ASICs. The performance of such assemble has been compared with a standard array of also 144 SiPM from SensL and a diode readout (AiT instruments) with 24 outputs corresponding to the number of rows and columns. The standard configuration easily permits to distinguish pixels of 1.57×1.57mm 2 with a timing resolution of 1.2ns. The custom configuration can hardly resolve pixels of 1.57×1.57mm 2 but reached a promising timing resolution of 750ps. This readout has the advantage to allow programing small array regions reducing the dark noise contribution. When 6×6 SiPMs are enabled, 1mm pixels are well resolved. Both approaches showed an energy resolution as good as 10%.
En esta tesis doctoral se presenta un sistema de fabricación de altas prestaciones de redes de difracción de Bragg en fibra. Las redes de difracción de Bragg en fibra son en la actualidad componentes ...cruciales en los modernos sistemas de comunicaciones ópticas al permitir, con un diseño adecuado, la implementación de prácticamente cualquier dispositivo de procesado de señales en el dominio óptico. Cuando se menciona el término "altas prestaciones", el autor se refiere a un sistema orientado fundamentalmente hacia la investigación, por lo que su principal característica debe de ser la versatilidad. El sistema de fabricación debe ser capaz de producir prácticamente cualquier red de difracción que sea concebida por los investigadores que utilizan el sistema, y con una calidad al menos comparable a la de las redes de difracción de Bragg producidas por las más modernos sistemas comerciales. Durante este trabajo de tesis se describe el sistema de fabricación de redes de difracción de Bragg implementado en el seno del Grupo de Comunicaciones Ópticas y Cuánticas de la UPV, detallando sus componentes, funcionamiento y prestaciones. También se presenta la base teórica que fundamenta este modelo. Adicionalmente, se muestra un estudio teórico de las propiedades de polarización de las redes de difracción (pérdidas dependientes de la polarización, retardo de grupo diferencial y parámetros de Stokes) y su validación experimental. Se demuestra como este estudio resulta de gran importancia tanto para el campo de las telecomunicaciones como para el del sensado. También se presentan aplicaciones de las redes de difracción producidas por este sistema al campo del sensado, mostrando ejemplos de aplicaciones al sensado de tensiones mecánicas en estructuras de hormigón o de acero, el desarrollo de un sensor multiparamétrico (tensión, temperatura, humedad y pH) para evaluar los daños que sufren dichas estructuras.
García Olcina, R. (2008). Sistema de fabricación de altas prestaciones de redes de difracción de bragg en fibra y aplicaciones al campo de los sensores ópticos y a los sistemas de comunicaciones ópticas Tesis doctoral no publicada. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/4323
Palancia
We demonstrate an integrated multi-wavelength laser based on semiconductor optical amplifiers, an arrayed waveguide grating, and on-chip Sagnac loop reflectors for signal processing (label generation ...and all-optical label swapping) of spectral amplitude code labels in packet-switched networks.
This paper describes the chromatic dispersion effect over the optical en/decoding process in coherent direct sequence (DS) systems and its respective verification by simulation and experimentally. ...The en/decoders are based on super structured fiber Bragg gratings (SSFBG) with 63 chips and binary optical phase codification with chip rates of 104 Gchip/s and 174 Gchip/s. This type of optical codification has been proposed for head processing in all optical photonic label switching (PLS) networks.
PDF
