Готові списки джерел за темами / Frequency domain multiplexing

Добірка наукової літератури з теми "Frequency domain multiplexing"

Автор: Grafiati
Опубліковано: 14 березня 2023

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Статті в журналах з теми "Frequency domain multiplexing"

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Chen, Xiang, Hao Liu, Mai Hu, Lu Yao, Zhenyu Xu, Hao Deng, and Ruifeng Kan. "Frequency-Domain Detection for Frequency-Division Multiplexing QEPAS." Sensors 22, no. 11 (May 26, 2022): 4030. http://dx.doi.org/10.3390/s22114030.

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To achieve multi-gas measurements of quartz-enhanced photoacoustic spectroscopy (QEPAS) sensors under a frequency-division multiplexing mode with a narrow modulation frequency interval, we report a frequency-domain detection method. A CH4 absorption line at 1653.72 nm and a CO2 absorption line at 2004.02 nm were investigated in this experiment. A modulation frequency interval of as narrow as 0.6 Hz for CH4 and CO2 detection was achieved. Frequency-domain 2f signals were obtained with a resolution of 0.125 Hz using a real-time frequency analyzer. With the multiple linear regressions of the frequency-domain 2f signals of various gas mixtures, small deviations within 2.5% and good linear relationships for gas detection were observed under the frequency-division multiplexing mode. Detection limits of 0.6 ppm for CH4 and 2.9 ppm for CO2 were simultaneously obtained. With the 0.6-Hz interval, the amplitudes of QEPAS signals will increase substantially since the modulation frequencies are closer to the resonant frequency of a QTF. Furthermore, the frequency-domain detection method with a narrow interval can realize precise gas measurements of more species with more lasers operating under the frequency-division multiplexing mode. Additionally, this method, with a narrow interval of modulation frequencies, can also realize frequency-division multiplexing detection for QEPAS sensors under low pressure despite the ultra-narrow bandwidth of the QTF.
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2

Lanting, T. M., Hsiao-Mei Cho, John Clarke, Matt Dobbs, Adrian T. Lee, M. Lueker, P. L. Richards, A. D. Smith, and H. G. Spieler. "Frequency domain multiplexing for bolometer arrays." Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 520, no. 1-3 (March 2004): 548–50. http://dx.doi.org/10.1016/j.nima.2003.11.311.

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3

Kim, Eun-Hee, Han-Saeng Kim, and Ki-Won Lee. "Range Dividing MIMO Waveform for Improving Tracking Performance." Sensors 21, no. 21 (November 2, 2021): 7290. http://dx.doi.org/10.3390/s21217290.

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A multiple-input multiple-output (MIMO) method that shares the same frequency band can efficiently increase radar performance. An essential element of a MIMO radar is the orthogonality of the waveform. Typically, orthogonality is obtained by spreading different signals into divided domains such as in time-domain multiplexing, frequency-domain multiplexing, and code domain multiplexing. This paper proposes a method of spreading the interference signals outside the range bins of interest for pulse doppler radars. This is achieved by changing the pulse repetition frequency under certain constraints, and an additional gain can be obtained by doppler processing. This method is very effective for improving the angular accuracy of the MIMO radar for a small number of air targets, although it may have limitations in use for many targets or in high clutter environments.
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4

Wang, Jing, and Dao-ben Li. "Overlapping Multiplexing in Both Time and Frequency Domain." Journal of Electronics & Information Technology 30, no. 5 (March 15, 2011): 1176–79. http://dx.doi.org/10.3724/sp.j.1146.2007.00541.

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5

Sakamoto, Takahide. "Orthogonal time-frequency domain multiplexing with multilevel signaling." Optics Express 22, no. 1 (January 7, 2014): 773. http://dx.doi.org/10.1364/oe.22.000773.

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6

Lanting, T. M., H. M. Cho, J. Clarke, M. A. Dobbs, W. L. Holzapfel, A. T. Lee, M. Lueker, P. L. Richards, A. D. Smith, and H. G. Spieler. "Frequency-Domain SQUID Multiplexing of Transition-Edge Sensors." IEEE Transactions on Appiled Superconductivity 15, no. 2 (June 2005): 567–70. http://dx.doi.org/10.1109/tasc.2005.849921.

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7

Mishra, M., J. Mattingly, J. M. Mueller, and R. M. Kolbas. "Frequency domain multiplexing of pulse mode radiation detectors." Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 902 (September 2018): 117–22. http://dx.doi.org/10.1016/j.nima.2018.06.023.

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8

Oh, W. Y., S. H. Yun, B. J. Vakoc, M. Shishkov, A. E. Desjardins, B. H. Park, J. F. de Boer, G. J. Tearney, and B. E. Bouma. "High-speed polarization sensitive optical frequency domain imaging with frequency multiplexing." Optics Express 16, no. 2 (January 14, 2008): 1096. http://dx.doi.org/10.1364/oe.16.001096.

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9

Arik, Sercan O., Daulet Askarov, and Joseph M. Kahn. "Adaptive Frequency-Domain Equalization in Mode-Division Multiplexing Systems." Journal of Lightwave Technology 32, no. 10 (May 2014): 1841–52. http://dx.doi.org/10.1109/jlt.2014.2303079.

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10

Xu, Q., H. Wang, Z. Xu, and G. Li. "Frequency domain multiplexing for parallel acquisition of MR images." Electronics Letters 42, no. 6 (2006): 326. http://dx.doi.org/10.1049/el:20063890.

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Більше джерел

Дисертації з теми "Frequency domain multiplexing"

1

Capindissa, Vladimir C. "Monitoring an industrial hydrocyclone using frequency domain multiplexing electrical impedance tomography." Master's thesis, University of Cape Town, 2005. http://hdl.handle.net/11427/5254.

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Анотація:
Includes bibliographical references (leaves 69-73).
This thesis describes the implementation of an Electrical Impedance Tomography (EIT) system using Frequency Domain Multiplexing (FDtvf) to monitor an industrial hydrocyclone. In order to utilise resources more effectively, to reduce negative environmental impact, to satisfy demands and legislations on product quality, there has been a rapid increase in research for optimisation and control of hydrocyclones, as industries consistently demand new and more cost effective ways of production. In an industrial setup, it is very difficult to determine the optimal operating point of a hydrocyclone. Tomography offers an exceptional opportunity to untangle the intricacies of the separation process structures without the intrusion of the sensing equipment or having to interfere with the process. The use of an Electrical Resistance Tomography (ERT) system with Time Domain Multiplexing (TDM) is one method used to try and solve this optimisation problem. At the University of Cape Town (UCT), an innovative Electrical Impedance Tomography (EIT) system using Frequency Domain Multiplexing (FDM) which is inherently faster than ERT TOM. This system increased the likelihood that a faster frame rate may be achieved for image reconstruction.
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2

Liu, Yuan. "FREQUENCY DOMAIN INDEPENDENT COMPONENT ANALYSIS APPLIED TO WIRELESS COMMUNICATIONS OVER FREQUENCY-SELECTIVE CHANNELS." Doctoral diss., University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3150.

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Анотація:
In wireless communications, frequency-selective fading is a major source of impairment for wireless communications. In this research, a novel Frequency-Domain Independent Component Analysis (ICA-F) approach is proposed to blindly separate and deconvolve signals traveling through frequency-selective, slow fading channels. Compared with existing time-domain approaches, the ICA-F is computationally efficient and possesses fast convergence properties. Simulation results confirm the effectiveness of the proposed ICA-F. Orthogonal Frequency Division Multiplexing (OFDM) systems are widely used in wireless communications nowadays. However, OFDM systems are very sensitive to Carrier Frequency Offset (CFO). Thus, an accurate CFO compensation technique is required in order to achieve acceptable performance. In this dissertation, two novel blind approaches are proposed to estimate and compensate for CFO within the range of half subcarrier spacing: a Maximum Likelihood CFO Correction approach (ML-CFOC), and a high-performance, low-computation Blind CFO Estimator (BCFOE). The Bit Error Rate (BER) improvement of the ML-CFOC is achieved at the expense of a modest increase in the computational requirements without sacrificing the system bandwidth or increasing the hardware complexity. The BCFOE outperforms the existing blind CFO estimator [25, 128], referred to as the YG-CFO estimator, in terms of BER and Mean Square Error (MSE), without increasing the computational complexity, sacrificing the system bandwidth, or increasing the hardware complexity. While both proposed techniques outperform the YG-CFO estimator, the BCFOE is better than the ML-CFOC technique. Extensive simulation results illustrate the performance of the ML-CFOC and BCFOE approaches.
Ph.D.
Department of Electrical and Computer Engineering
Engineering and Computer Science
Electrical Engineering
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3

McKinley, Michael Dean. "Improved frequency domain measurement techniques for characterizing power amplifier and multipath environments." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/24722.

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Анотація:
Thesis (Ph.D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2009.
Committee Chair: James Stevenson Kenney; Committee Member: Gregory David Durgin; Committee Member: Madhavan Swaminathan
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4

VACCARO, DAVIDE. "Development of the FDM readout for the LSPE/SWIPE experiment." Doctoral thesis, Università di Siena, 2018. http://hdl.handle.net/11365/1064717.

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The Large Scale Polarization Explorer (LSPE) is the combination of a ground-based experiment and a balloon-borne mission designed to measure or to set an upper limit on the B-mode polarization pattern of the cosmic microwave background (CMB), providing a compelling evidence in support of cosmological inflationary theories. The Short Wavelength Instrument for the Polarization Explorer (SWIPE), its balloon-borne instrument, will be launched from Longyearbyen (Svalbard Island, 78° N) for a long-duration flight during the winter night, operating in a space-like environment at an altitude of 40 km. SWIPE is a Stokes polarimeter that will measure the CMB polarization exploiting three hundred large-area spider-web transition-edge sensors (TES), coupled to the optical stages of the instrument through multi-mode horns. The readout electronics of SWIPE is based on a frequency-domain multiplexing (FDM) system, composed of a “warm” section at roughly -90 °C, the temperature of the stratosphere during the polar night, and of a “cold” section hosted on the 300 mK and the 1.6 K stages of the instrument. This thesis focuses on the prototyping (design, development, and test) of FDM electronics for SWIPE, as well as a contribution to the characterization of the TES bolometers fabricated at INFN Genova. Though the design of LSPE/SWIPE is frozen, its construction and development are still in progress: therefore, the work presented here represents a snapshot of the R&D that we started from scratch in the laboratories of INFN Pisa, from the set-up of the cryogenic test facility to the fabrication and measurement of superconducting devices at sub-kelvin temperatures.
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5

Hervas, García Marcos Antonio. "Channel Sounding and physical layer definition for the HF long-haul link between Antarctica and Spain." Doctoral thesis, Universitat Ramon Llull, 2016. http://hdl.handle.net/10803/359395.

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Анотація:
La comunicació per rebot ionosfèric en la banda d’HF es presenta com una bona candidata en l’establiment de trucades i transmissió de dades per aplicacions militars, països en vies de desenvolupament, catàstrofes naturals o com a sistema de backup gràcies a la senzillesa de desplegament del sistema i al baix cost que suposa. Els estàndars actuals de comunicacions HF defineixen bit rates entre 75 i 12.800 bps, depenent de les condicions del canal, usant un ample de banda de 3 kHz. Els ultims avanços inclouen funcionalitats d’Automatic Link Establishment (ALE) i Automatic Repeat Request (ARQ), permitint establir l’enllaç de comunicació i solicitant la retransmissió de dades quan un paquet s’hagi perdut de manera automàtica, sense la necessitat de que l’usuari sigui un tècnic expert. En aquest projecte s’han definit dos objectius científics: i) estudiar la variabilitat d’aquest canal ionosfèric HF durant un cicle solar complet i ii) proposar una nova capa física adaptada a aquest canal. Aquesta tecnologia s’utilitza com a sistema de transmissió de les dades dels sensors instal·lats en la Antarctic Station Juan Carlos I (ASJI) per la comunitat científica desplaçada a l'illa i Cambrils (Espanya), establint un ràdioenllaç unidireccional de 12.760 km. El sistema implementat és de molt baixa potència, 200 W, utilitzant un senzill monopol en transmissió a causa de les restriccions mediambientals imposades pel tractat antàrtic. S’han revisat els distints estàndards d’HF per poder desplegar aquest ràdioenllaç, no obstant això, cap d’ells compleix amb el baix nivell de SNR observat. Per tant, s’ha de dissenyar un nou esquema de modulació per poder establir la comunicació. Aquesta tesi aplica els sondejos de banda estreta i banda ampla per a l'estudi de la variabilitat del canal, aplicant-los a la campanya 2013-2014 i obtenint els resultats d’aquesta per mantenir la sèrie històrica. Per a la proposta de capa física, s'han estudiat tècniques de modulació multi-carrier i d’espectre eixamplat, a partir de resultats previs, i s’analitzen i proven diverses tècniques de single carrier. Finalment, s’han definit dos propostes de trama de capa física per utilitzar-les en condicions de canal pobre (HRM - High Robustness Mode) i moderado (HTM - High Throughput Mode).
La comunicación por rebote ionosférico en la banda de HF se presenta como un buen candidato en el establecimiento de llamadas y transmisión de datos en aplicaciones militares, países en vías de desarrollo, catástrofes naturales o como sistema de backup gracias a la sencillez del despliegue del sistema y al bajo coste que supone. Los estándares actuales de comunicaciones HF definen bit rates entre 75 y 12.800 bps, dependiendo de las condiciones del canal, empleando un ancho de banda de 3 kHz. Los últimos avances incluyen funcionalidades de Automatic Link Establishment (ALE) y Automatic Repeat Request (ARQ), permitiendo establecer el enlace de comunicación y solicitando la retransmisión de datos cuando un paquete se haya perdido de manera automática, sin la necesidad de que el usuario sea un técnico experto. En este proyecto se han definido dos objetivos científicos: i) estudiar la variabilidad de este canal ionosférico HF durante un ciclo solar completo y ii) proponer una nueva capa física adaptada a este canal. Esta tecnología se emplea como sistema de transmisión de los datos de los sensores instalados en la Antarctic Station Juan Carlos I (ASJI) por la comunidad científica desplazada a la isla y Cambrils (España), estableciendo un radio enlace unidireccional de 12.760km. El sistema implementado es de muy baja potencia, 200 W, empleando un sencillo monopolo en transmisión debido a las restricciones medioambientales impuestas por el tratado antártico. Se han revisado los distintos estándares de HF para poder desplegar este radio-enlace, sin embargo, ninguno de ellos cumple con los bajos niveles de SNR observados. Por lo tanto, se debe diseñar un nuevo esquema de modulación para poder establecer la comunicación. Esta tesis aplica los sondeos de banda estrecha y banda ancha para el estudio de la variabilidad del canal, aplicándolos a la campaña 2013-2014 y obteniendo los resultados de ésta para mantener la serie histórica. Para la propuesta de capa física, se estudian técnicas de modulación multi-carrier y de espectro ensanchado, a partir de resultados previos, y se analizan y prueban diversas técnicas de single carrier. Finalmente, se han definido dos propuestas de trama de capa física para emplear en condiciones de canal pobre (HRM - High Robustness Mode) y moderado (HTM - High Throughput Mode).
Ionospheric communication in the HF band is presented as a candidate in call establishment and data transmission in military applications, developing countries and natural disasters, or as a backup system due to the simplicity of the system deployment and the low cost involved. Current HF communications standards define bit rates between 75 and 12,800 bps, depending on channel conditions, using a bandwidth of 3 kHz. Recent advances include Automatic Link Establishment (ALE) and Automatic Repeat Request (ARQ) features, allowing establishing the communication link and requesting retransmission of data automatically when a packet is lost, without expert technical requirements. In this project, we have defined two scientific objectives: i) to study the variability of the ionospheric HF channel during a complete solar cycle, and ii) propose a new physical layer adapted to this channel performance. This technology is used by the scientific community in the island as a data transmission system from the sensors installed in the Antarctic Station Juan Carlos I (ASJI) to Cambrils (Spain). Establishing a unidirectional link of 12.760 km. The implemented system has low power transmission requirements, 200 W, and uses a simple monopole due to environmental restrictions imposed by the Antarctic Treaty. We reviewed the various standards to deploy this HF radio link, however, none of them meet the low SNR observed in the channel. Therefore, we must design a new modulation scheme to establish a communication channel between Antarctica and Spain. This thesis applies narrowband and wideband sounding to study the variability of the channel performance. Both techniques have been applied to the 2013-2014 campaign data obtaining the results to maintain the historical series. To propose the physical layer, multi-carrier and spread spectrum modulation techniques had been previously studied, and new single carrier techniques has been analyzed and tested. Finally, two physical layer proposals have been defined to be used with poor channel conditions (HRM - High Robustness Mode) and moderate channel conditions (HTM - High Throughput Mode).
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6

Calo, Cosimo. "Quantum dot based mode locked lasers for optical frequency combs." Thesis, Evry, Institut national des télécommunications, 2014. http://www.theses.fr/2014TELE0034/document.

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Анотація:
Les peignes de longueurs d'onde, produisant des dizaines de porteuses optiques régulièrement espacées à partir d'une seule source laser, présentent un grand intérêt pour les systèmes de communication à haut débit. Ce travail de thèse porte sur les peignes générés par les diodes laser à blocage de modes basées sur des nanostructures semi-conductrices à basse dimensionnalité. Dans cette étude, les performances en verrouillage de modes de lasers Fabry-Pérot mono-section basés sur différents systèmes de matériaux sont comparées sur la base de la largeur du spectre optique d'émission et de la capacité à produire des impulsions courtes à faible gigue temporelle. En remarquant que les lasers à base de bâtonnets quantiques InAs sur InP présentent de meilleures caractéristiques par rapport aux autres matériaux examinés, leurs propriétés spécifiques en termes de stabilité des peignes de fréquences optiques et de chirp des impulsions sont étudiées plus en détail. Le chirp est d'abord étudié par la technique FROG (frequency-resolved optical gating). Ensuite, la dispersion chromatique du matériau laser est évaluée afin de vérifier si elle peut expliquer les grandes valeurs de chirp mesurées par FROG. Pour cela la technique de réflectométrie optique dans le domaine fréquentiel est utilisée et ses capacités uniques de mesure ont été étudiées et validées. Enfin, ces lasers sont employés avec succès pour les transmissions haut débit à l'aide de la technique de modulation optique OFDM (orthogonal frequency-division multiplexing) en détection directe. Débits de l'ordre du térabit par seconde, ainsi que le faible coût de l’architecture du système, sont très prometteurs pour les data centers
Optical frequency combs, generating tens of equally spaced optical carriers from a single laser source, are very attractive for next-generation wavelength division multiplexing (WDM) communication systems. This PhD thesis presents a study on the optical frequency combs generated by mode-locked laser diodes based on low-dimensional semiconductor nanostructures. In this work, the mode-locking performances of single-section Fabry-Pérot lasers based on different material systems are compared on the basis of the optical spectrum width, the timing jitter and pulse generation capabilities. Then, noticing that InAs quantum dashes grown on InP exhibit on average better characteristics than other examined materials, their unique properties in terms of comb stability and pulse chirp are studied in more detail. Laser chirp, in particular, is first investigated by frequency resolved optical gating (FROG) characterizations. Then, chromatic dispersion of the laser material is assessed in order to verify whether it can account for the large chirp values measured by FROG. For that, a high sensitivity optical frequency-domain reflectometry setup is used and its measurement capabilities are extensively studied and validated. Finally, the combs generated by quantum dash mode-locked lasers are successfully employed for high data rate transmissions using direct-detection optical orthogonal frequency division multiplexing. Terabit per second capacities, as well as the low cost of this system architecture, appear to be particularly promising for future datacom applications
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7

Liu, Ming. "Analyse et optimisation du système asiatique de diffusion terrestre et mobile de la télévision numérique." Phd thesis, INSA de Rennes, 2011. http://tel.archives-ouvertes.fr/tel-00662247.

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Анотація:
Cette thèse a pour objectif l'analyse du système de télévision numérique chinois (DTMB) et l'optimisation de sa fonction d'estimation de canal. Tout d'abord, une analyse approfondie de ce système est effectuée en comparaison du système DVB-T en termes de spécifications, d'efficacité spectrale et de performances. Ensuite, la fonction d'estimation de canal basée sur la séquence pseudo-aléatoire du système est étudiée dans les domaines temporel et fréquentiel, et plusieurs améliorations sont apportées aux méthodes typiques afin de notamment gérer les canaux très dispersifs en temps. Enfin, de nouveaux procédés itératifs aidés par les données et peu complexes sont proposés pour raffiner les estimés de canal. Les fonctions de décodage de canal et d'entrelacement sont exclues de la boucle et des fonctions de filtrage temps/fréquence sont étudiées pour fiabiliser les estimations. Ces nouveaux algorithmes démontrent leur efficacité par rapport aux méthodes courantes de la littérature.
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8

Silva, Andreia Pereira da. "Low Complexity Iterative Frequency Domain Equalisation for MIMO-OFDM Type Systems." Master's thesis, 2016. http://hdl.handle.net/10316/83157.

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Анотація:
Dissertação de Mestrado Integrado em Engenharia Electrotécnica e de Computadores apresentada à Faculdade de Ciências e Tecnologia
As comunicações sem fios são, sem sombra de dúvida, o segmento de mais rápido crescimento da indústria de comunicações. Não só os telemóveis, que se tornaram uma ferramenta fulcral no mundo dos negócios e parte da vida quotidiana em todo o mundo, mas também os computadores e outros dispositivos de consumo de dados têm vindo a experienciar um crescimento exponencial na última década, trazendo novos desafios para a próxima geração de sistemas sem fios. As redes sem fio de quinta geração como próximo standard deverão ser capazes de satisfazer os requisitos impostos pela crescente procura de maior capacidade, ao mesmo tempo que garantem robustez, fiabilidade e maiores taxas de transferência.Uma das alternativas mais promissoras consiste no aumento do número de antenas tanto no transmissorcomo no recetor, isto é sistemas MIMO, que beneficiam de técnicas de processamento de sinal explorando uma diversidade adicional permitindo uma maior eficiência espectral ou uma transmissão robusta. No que diz respeito à obtenção de taxas de transferência de dados maiores e uma capacidade aumentada, empregando multiplexagem espacial combinada com sistemas OFDM ou que derivem dos mesmos é vista como uma das soluções mais poderosas. Particularmente, quando novas técnicas, como o TIBWB-OFDM, são adotados é possível obter um sistema de comunicação sem fios com uma melhor eficiência espectral e energética, robusto aos desvanecimentos profundos do canal selectivo na frequência.No entanto, existe alguma complexidade computacional inerente aos sistemas MIMO, que aumenta com onúmero de antenas no sistema, tornando o recetor muito mais complexo, nomeadamente na fase de equalização onde equalizadores presentes no estado de arte, como o MMSE e ZF, necessitam de inversões de matrizes de altas dimensões. Para superar este problema, é crucial considerar recetores iterativos, tais como EGC e MRC, que não requerem inversões de matrizes de canal de altas dimensões e, como tal, o recetor pode ser mantido a uma complexidade razoável.Portanto, o objetivo principal deste trabalho é conseguir um sistema com alta eficiência tanto a nívelespectral como a nível energético, capaz de lidar com as deficiências do canal MIMO, enquanto a complexidade do recetor se mantém reduzida através do uso de técnicas que não necessitem de inverter as matrizes de canal. Os resultados obtidos mostraram que empregar equalizadores lineares ou não lineares, tais como o EGC and MRC, permite ganhos substanciais relativamente ao sistema conventional MIMO usando o prefixo cíclico como intervalo de guarda nas mesmas condições. Além disso, os métodos iterativos de baixa complexidade mostraram um melhor desempenho quando usados em esquemas do tipo MIMO TIBWB-OFDM, sendo conseguido um desempenho excelente capaz de aproximar o match filter bound com apenas algumas iterações.
Wireless communications are, by any measure, the fastest growing segment of the communications industry. Not only the cellular phones, which have become a critical business tool and part of everyday lifeworldwide, but also computers and other data consuming devices have experienced exponential growth over the last decade, bringing some new challenges to the next generation wireless systems. Fifth generation wireless networks as the next standard must be able to meet the requirements imposed by the ever increasing demand in capacity, while guaranteeing robustness, reliability and higher data rates.One of the most promising alternatives is the increase in the number of antennas in both transmitterand receiver, i.e. multiple-input multiple-output (MIMO) systems, which leveraged on signal processingtechniques exploring added diversity may allow for higher spectral efficiency or improved robustness transmission. Regarding to achieve higher data rates and an increased capacity, employing spatial multiplexing combined with orthogonal frequency division multiplexing (OFDM) type systems is seen as one of most potential solutions. Particularly, when new techniques, such as the time-interleaved block-windowed burst OFDM (TIBWB-OFDM), are adopted is possible to achieve a highly spectral and power efficient wireless communication system, robust to the deep fades of the selective-frequency channel.However, there is some computational complexity inherent to the MIMO systems, that grows with thenumber of antennas elements, making the receiver much more complex, namely the equalisation stage where state-of-the art equalisers, such as minimum mean squared error (MMSE) and zero forcing (ZF), require for the inversion of the channel’s high dimension matrix. To overcome this problem, it is crucial to consider low complexity frequency-domain iterative receivers, such as equal gain combiner (EGC) and maximum ratio combiner (MRC), which do not require high dimension channel matrices inversions and as so, the receiver can be kept at an affordable complexity.Therefore, the main goal of this work is to achieve a spectral and power efficient system able to handle withthe impairments of the frequency-selective MIMO channel, while keeping the receiver complexity reducedthrough the use of techniques that does not require channel matrix inversions. Performance results shownthat employing linear equalisers or nonlinear equalisers, such as EGC and MRC, allows substantial gainsover the conventional MIMO employing cyclic prefix technique, in the same conditions. Furthermore, lowcomplexity iterative methods have their best performances when employed in the multiple-input multiple- output TIBWB-OFDM (MIMO TIBWB-OFDM) scheme, achieving excellent performance and approachingthe matched filter bound (MFB) with just a few iterations.
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Nunes, João Filipe Teles. "Sistema OFDM multi-símbolo: Uma abordagem multiportadora eficiente." Master's thesis, 2014. http://hdl.handle.net/10316/40464.

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Dissertação de Mestrado Integrado em Engenharia Electrotécnica e de Computadores apresentada à Faculdade de Ciências e Tecnologia da Universidade de Coimbra
Desde a transmissão do primeiro símbolo Morse as exigências relativas ao aumento da largura de banda não têm abrandado. Com a expansão das comunicações móveis pessoais e da oferta de serviços multimédia, cresce a necessidade de transmitir eficientemente sobre canais de largura de banda limitada, a taxas de transmissão variáveis, e sobre condições de canal hostis. Ao longo das últimas duas décadas, a técnica Orthogonal Frequency Division Multiplexing (OFDM) tem abordado esta questão de forma assertiva devido à robustez que apresenta em canais dispersivos, graças ao intervalo de guarda adicionado a cada símbolo consecutivo e à baixa complexidade na geração do sinal através de uma Transformada Rápida de Fourier (IFFT) que permite dividir a largura de banda do canal em pequenas sub-bandas mais estreitas. Apesar do facto de a adição de um intervalo de guarda conduzir a uma igualização no domínio da frequência (FDE), com apenas um factor multiplicativo por subportadora, esta é pura redundância (que pode variar entre 0.125− 0.25% do período do símbolo), reduzindo a taxa efectiva de transmissão e subsequentemente a eficiência espectral. Além disso, devido à forma retangular do símbolo OFDM, este apresenta elevados níveis de radiação fora de banda, que levam a interferência entre canais adjacentes. O debate actual sobre a próxima geração de redes sem-fios deixa bastante claro que o futuro das comunicações móveis está assente num aumento das taxas de transmissão, maior eficiência espectral e condições de flexibilidade. O objectivo principal deste trabalho é introduzir um novo esquema de transmissão intitulado Block-Windowed Burst OFDM (BWB-OFDM). Esta é uma técnica de transmissão multiportadora que emprega janelas no transmissor com transições mais suaves, que apontam alcançar um compromisso entre taxas de transmissão efectivas mais elevadas e um maior confinamento espectral. Ao impôr maior exigência na igualização no domínio da frequência, a adição do intervalo de guarda deixa de ser necessário, levando a um considerável aumento da eficiência de potência comparado com o CP-OFDM. É também apresentado um receptor apropriado para canais dispersivos, que permitem um ganho de 2 dB relativamente a esquemas OFDM convencionais, em termos de bit-error rate.
The advent and expansion of personal mobile communications brings the necessity to transmit efficiently and wirelessly over wide bandwidths at changing rates over hostile channel conditions. Over the past two decades, Orthogonal Frequency Division Multiplexing (OFDM) has tackled this issue in an assertive way due to its robustness over multipath propagation, owing to a time guard interval added to each symbol, and trivial signal generation/separation through the Fast Fourier Transform processing blocks (IFFT/FFT). Despite the fact that cyclic prefix (CP) leads to a simplified frequency domain equalisation (FDE) with only a single tap equaliser per carrier, it is pure redundancy (that can vary between 0.125−0.25% of symbol period), reducing the effective throughput and worsening the spectral efficiency. In addition, the rectangular shape of OFDM symbol induces large levels of out-of-band radiation, leading to adjacent channel interference. The debate over the next generation mobile network standards has made clear that the future of wireless communication stands on higher data rates, spectral efficiency and flexibility requirements. The main goal of this work is to introduce a new transceiver scheme called BlockWindowed Burst OFDM (BWB-OFDM), which is a multicarrier technique that employs smoother, non-rectangular windows, on the transmitter side, that aims to reach a compromise between higher data rate and better spectrum confinement. By stressing the frequency domain equalisation the cyclic prefix is no longer needed, which means the overall power and spectral efficiencies are higher. It is also presented an appropriate receiver for typical time-dispersive channels, allowing 2 dB of gain relatively conventional OFDM schemes in bit-error rate.
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10

Correia, Pedro Gonçalves. "Amplificação de potência energeticamente eficiente para sinais mono portadora e multi portadora." Master's thesis, 2018. http://hdl.handle.net/10362/121789.

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Os recentes avanços tecnológicos, permitiram não só o desenvolvimento da rede móvel, como também permitiram a massificação de dispositivos móveis. Com o crescimento exponencial de utilizadores da rede celular, é necessário garantir ritmos de transmissão elevados e uma redução no consumo energético por parte dos dipositivos. Para garantir ritmos de transmissão elevados, são utilizados sinais multi-portadora como o OFDM (Orthogonal Frequency Division Multiplexing) ou sinais SC-FDE (Single Carrier Frequency Domain Equalization). No entanto, estes sinais são caracterizados por elevada PAPR (Peak-to-AveragePower Ratio) levando a que seja necessário sobre dimensionar os amplificadores de acordo com a gama dinâmica do sinal, sacrificando assim a eficiência energética. Neste trabalho, é proposto um transmissor que realiza uma quantização da envolvente complexa de sinal com elevada PAPR, dividindo-a num somatório de componentes com envolvente constante, permitindo assim utilizar amplificadores a operar na zona de saturação ou próximo desta, minimizando os efeitos não lineares por parte dos amplificadores ao mesmo tempo que se maximiza a eficiência energética do transmissor.
The recent technological advances enabled not only the development of the mobile communication systems, but also led to the massification of mobile devices. While the increase number of users of the cellular network, it is necessary to guarantee high transmis-sion rates and reduced energy consumption by the devices. Signals like OFDM (Orthog-onal Frequency Division Multiplexing) or SC-FDE (Single Carrier Frequency Domain Equalization) can be used to maintain high transmission rates, however, these signals are characterized by high PAPR (Peak-to-Mean Power Ratio) which require linear amplifiers that can amplify the signals accordingly with their dynamic range, thus sacrificing the power efficiency of the amplifiers. In this work, it is proposed a transmitter that performs a signal processing that allows to divide a signal with a high PAPR into a sum of components that have constant envelope. Since the components have constant envelope, it allows the use of amplifiers operating near the saturation zone, minimizing the effects of nonlinear effects of the amplifier while maximizing the power efficiency of the transmitter.
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Частини книг з теми "Frequency domain multiplexing"

1

Song, Jian. "Time-Domain Synchronous Orthogonal Frequency Division Multiplexing." In Encyclopedia of Wireless Networks, 1400–1403. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-319-78262-1_167.

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Song, Jian. "Time-Domain Synchronous Orthogonal Frequency Division Multiplexing." In Encyclopedia of Wireless Networks, 1–4. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-32903-1_167-1.

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3

Panazio, Cristiano, and Renato Lopes. "Principles of orthogonal frequency division multiplexing and single carrier frequency domain equalisation." In Power Line Communication Systems for Smart Grids, 83–105. Institution of Engineering and Technology, 2018. http://dx.doi.org/10.1049/pbpo132e_ch4.

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4

Kaur, Inderjeet. "Frequency Domain Equalization and Adaptive OFDM vs. Single Carrier Modulation." In Innovations in Mobile Multimedia Communications and Applications, 126–32. IGI Global, 2011. http://dx.doi.org/10.4018/978-1-60960-563-6.ch009.

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In the present article an attempt is made to compare multi-carrier and single carrier modulation schemes for wireless communication systems with the utilization of fast Fourier transform (FFT) and its inverse in both cases. With the assumption that in OFDM (orthogonal frequency division multiplexing), the inverse FFT transforms the complex amplitudes of the individual sub-carriers at the transmitter into time domain, the inverse operation is carried out at the receiver. In case of single carrier modulation, the FFT and its inverse are used at the input and output of the frequency domain equalizer in the receiver. Different single carrier and multi-carrier transmission systems are simulated with time-variant transfer functions measured with a wideband channel sounder. In case of OFDM, the individual sub-carriers are modulated with fixed and adaptive signal alphabets. Furthermore, a frequency-independent as well as the optimum power distribution are used. Single carrier modulation uses a single carrier, instead of the hundreds or thousands typically used in OFDM, so the peak-to-average transmitted power ratio for single carrier modulated signals is smaller. This in turn means that a SC system requires a smaller linear range to support a given average power. This enables the use of cheaper power amplifier as compared to OFDM system.[Article copies are available for purchase from InfoSci-on-Demand.com]
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5

Al Bassam, Nizar, Vidhyalavanya Ramachandran, and Sumesh Eratt Parameswaran. "Wavelet Theory and Application in Communication and Signal Processing." In Wavelet Theory. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.95047.

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Wavelet analysis is the recent development in applied mathematics. For several applications, Fourier analysis fails to provide tangible results due to non-stationary behavior of signals. In such situation, wavelet transforms can be used as a potential alternative. The book chapter starts with the description about importance of frequency domain representation with the concept of Fourier series and Fourier transform for periodic, aperiodic signals in continuous and discrete domain followed by shortcoming of Fourier transform. Further, Short Time Fourier Transform (STFT) will be discussed to induce the concept of time frequency analysis. Explanation of Continuous Wavelet Transform (CWT) and Discrete Wavelet Transform (DWT) will be provided with the help of theoretical approach involving mathematical equations. Decomposition of 1D and 2D signals will be discussed suitable examples, leading to application concept. Wavelet based communication systems are becoming popular due to growing multimedia applications. Wavelet based Orthogonal Frequency Division Multiplexing (OFDM) technique and its merit also presented. Biomedical signal processing is an emerging field where wavelet provides considerable improvement in performance ranging from extraction of abnormal areas and improved feature extraction scheme for further processing. Advancement in multimedia systems together with the developments in wireless technologies demands effective data compression schemes. Wavelet transform along with EZW, SPIHT algorithms are discussed. The chapter will be a useful guide to undergraduate and post graduate who would like to conduct a research study that include wavelet transform and its usage.
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6

SivachandarK., V. Amudha, B. Ramesh, Jose Anand, M. ShanmugaSundari, and Jerril Gilda S. "MIMO-IDMA System Performance for SUI and LTE Frequency Selective Channels." In Advances in Parallel Computing Algorithms, Tools and Paradigms. IOS Press, 2022. http://dx.doi.org/10.3233/apc220059.

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The spectrum used by Code Division Multiple Access (CDMA) allows for a signal with a greater bandwidth by spreading electromagnetic energy. Multi-Carrier CDMA (MC-CDMA) is a telecommunications numerousentrée strategy that spreads each user symbol across the frequency domain with distinct codes. Cognitive Radio (CR) is a vibrant spectrum admittance enabling technology by dynamically allocating space for fundamental users by modifying its settings and base station. Two models for people on the cognitive spectrum are Opportunistic Spectrum Access (OSA) and Concurrent Spectrum Access (CSA). Using Co-Channel Interference (CCI) and Adjacent Channel Interference (ACI), the MC-CDMA system is an effective accessing strategy for multi-user data transmission (ACI). Multiple-Input Multiple-Output (MIMO) involving Space-Time Transmit Diversity (STTD), Spatial Multiplexing (SM), and collaborative MIMO is used for numerous data communication, and dependable Bit Error Rate (BER) presentation is attained. STBC (Space Time Block Coding) is equipped with two antennas and codes for data transmission across multiple antennas. At the receiver, STBC offers channel state information while maintaining a low level of complexity. The image’s pixels will be shuffled using Arnold’s Cat Map (ACM) encryption method. When compared to other compression methods, Integer Wavelet Transform (IWT) compression is stress-free. The Internet of Things (IoT) is used to examine tracklatency and power stages, STTD MC-CDMA faultoutput utilizing cognitive spectrum, and channel simulated parameterization. The output on fault levels with patient caring using Stanford University Interim (SUI) and Long Term Evolution (LTE) techniques with a Double STTD (DSTTD) assisted MC-CDMA cognitive spectrum system.
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7

Rohling, Hermann. "OFDM Transmission Technique." In Mobile Computing, 3561–87. IGI Global, 2009. http://dx.doi.org/10.4018/978-1-60566-054-7.ch260.

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The orthogonal frequency division multiplexing (OFDM) transmission technique can efficiently deal with multi-path propagation effects especially in broadband radio channels. It also has a high degree of system flexibility in multiple access schemes by combining the conventional TDMA; FDMA; and CDMA approaches with the OFDM modulation procedure; which is especially important in the uplink of a multi-user system. In OFDM-FDMA schemes carrier synchronization and the resulting sub-carrier orthogonality plays an important role to avoid any multiple access interferences (MAI) in the base station receiver. An additional technical challenge in system design is the required amplifier linearity to avoid any non-linear effects caused by a large peak-to-average ratio (PAR) of an OFDM signal. The OFDM transmission technique is used for the time being in some broadcast applications (DVB-T; DAB; DRM) and wireless local loop (WLL) standards (HIPERLAN/2; IEEE 802.11a) but OFDM has not been used so far in cellular communication networks. The general idea of the OFDM scheme is to split the total bandwidth into many narrowband sub-channels which are equidistantly distributed on the frequency axis. The sub-channel spectra overlap each other but the sub-carriers are still orthogonal in the receiver and can therefore be separated by a Fourier transformation. The system flexibility and use of sub-carrier specific adaptive modulation schemes in frequency selective radio channels are some advantages which make the OFDM transmission technique a strong and technically attractive candidate for the next generation of mobile communications. The objective of this chapter is to describe an OFDM-based system concept for the fourth generation (4G) of mobile communications and to discuss all technical details when establishing a cellular network which requires synchronization in time and frequency domain with sufficient accuracy. In this cellular environment a flexible frequency division multiple access scheme based on OFDM-FDMA is developed and a radio resource management (RRM) employing dynamic channel allocation (DCA) techniques is used. A purely decentralized and self-organized synchronization technique using specific test signals and RRM techniques based on co-channel interference (CCI) measurements has been developed and will be described in this chapter.
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Тези доповідей конференцій з теми "Frequency domain multiplexing"

1

Lanting, Trevor M., Hsiao-Mei Cho, John Clarke, Matthew Dobbs, Adrian T. Lee, Paul L. Richards, Helmuth Spieler, and A. Smith. "Frequency-domain multiplexing for large-scale bolometer arrays." In Astronomical Telescopes and Instrumentation, edited by Thomas G. Phillips and Jonas Zmuidzinas. SPIE, 2003. http://dx.doi.org/10.1117/12.459672.

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2

Tai, Ching-Lun, Borching Su, and Cai Jia. "Frequency-domain Decoupling for MIMO-GFDM Spatial Multiplexing." In ICASSP 2019 - 2019 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP). IEEE, 2019. http://dx.doi.org/10.1109/icassp.2019.8682308.

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3

Yu, Guoqiang, Turgut Durduran, Daisuke Furuya, Regine Choe, Joel H. Greenberg, and Arjun G. Yodh. "Frequency domain diffuse optical multiplexing system for rapid hemodynamics." In Biomedical Topical Meeting. Washington, D.C.: OSA, 2002. http://dx.doi.org/10.1364/bio.2002.sue4.

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4

Stralka, John P. "OFDM-based digital array radar with frequency domain mode multiplexing." In 2010 IEEE Radar Conference. IEEE, 2010. http://dx.doi.org/10.1109/radar.2010.5494607.

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5

Chan, Peter K. C., Wei Jin, and M. Suleyman Demokan. "Frequency domain technique for multiplexing of fiber Bragg grating sensors." In International Symposium on Photonics and Applications, edited by Robert A. Lieberman, Anand K. Asundi, and Hiroshi Asanuma. SPIE, 1999. http://dx.doi.org/10.1117/12.369345.

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Jarzebinska, Renata, Edmon Chehura, Stephen W. James, and Ralph P. Tatam. "Multiplexing tapered optical fibres using coherent optical frequency domain reflectometry." In OFS2012 22nd International Conference on Optical Fiber Sensor, edited by Yanbiao Liao, Wei Jin, David D. Sampson, Ryozo Yamauchi, Youngjoo Chung, Kentaro Nakamura, and Yunjiang Rao. SPIE, 2012. http://dx.doi.org/10.1117/12.965549.

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7

Sakamoto, Takahide. "Time-Frequency Domain Signaling/Multiplexing for Optical Filter-less Networking." In Photonic Networks and Devices. Washington, D.C.: OSA, 2013. http://dx.doi.org/10.1364/networks.2013.nw3c.2.

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8

Belling, Samuel W., Lorenzo Fabris, John Mattingly, Mudit Mishra, Jason Newby, and Phil Barbeau. "A Frequency Domain Multiplexing Technique for Multi-Channel Detector Instrumentation." In 2018 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC). IEEE, 2018. http://dx.doi.org/10.1109/nssmic.2018.8824306.

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9

Zhao, Chunxu, Su Zhang, Di Liu, Juhao Li, Fan Zhang, and Zhangyuan Chen. "Coherent Optical Single-carrier Frequency-division-multiplexing System with Overlap Frequency Domain Equalization." In Signal Processing in Photonic Communications. Washington, D.C.: OSA, 2012. http://dx.doi.org/10.1364/sppcom.2012.spth1b.2.

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Binaie, Ali, Sohail Ahasan, Armagan Dascurcu, Mahmood Baraani Dastjerdi, Robin Garg, Manoj Johnson, Arman Galioglu, Arun Natarajan, and Harish Krishnaswamy. "A Scalable 60GHz 4-Element MIMO Transmitter with a Frequency-Domain-Multiplexing Single-Wire Interface and Harmonic-Rejection-Based De-Multiplexing." In 2020 IEEE Radio Frequency Integrated Circuits Symposium (RFIC). IEEE, 2020. http://dx.doi.org/10.1109/rfic49505.2020.9218431.

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Звіти організацій з теми "Frequency domain multiplexing"

1

Kreger, Stephen, Sean Calvert, and Eric Udd. Optical Frequency Domain Reflectometry for High Density Multiplexing of Multi-Axis Fiber Bragg Gratings. Fort Belvoir, VA: Defense Technical Information Center, January 2003. http://dx.doi.org/10.21236/ada451483.

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