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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

RADIO FREQUENCY OVERVIEW OF THE HIGH EXPLOSIVE RADIO TELEMETRY PROJECT

Bracht, Roger, Dimsdle, Jeff, Rich, Dave, Smith, Frank 10 1900 (has links)
International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, California / High explosive radio telemetry (HERT) is a project that is being developed jointly by Los Alamos National Laboratory and AlliedSignal FM&T. The ultimate goal is to develop a small, modular telemetry system capable of high-speed detection of explosive events, with an accuracy on the order of 10 nanoseconds. The reliable telemetry of this data, from a high-speed missile trajectory, is a very challenging opportunity. All captured data must be transmitted in less than 20 microseconds of time duration. This requires a high bits/Hertz microwave telemetry modulation code to insure transmission of the data within the limited time interval available.
22

High Explosive Radio Telemetry System

Crawford, Ted, Bracht, Roger, Johnson, Richard, Mclaughlin, Barry 10 1900 (has links)
International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, California / This paper overviews the High Explosive Radio Telemetry (HERT) system, under co-development by Los Alamos National Laboratories and AlliedSignal Federal Manufacturing & Technologies. This telemetry system is designed to measure the initial performance of an explosive package under flight environment conditions, transmitting data from up to 64 sensors. It features high speed, accurate time resolution (10 ns) and has the ability to complete transmission of data before the system is destroyed by the explosion. In order to affect the resources and performance of a flight delivery vehicle as little as possible, the system is designed such that physical size, power requirements, and antenna demands are as small as possible.
23

An active audio attenuator

Laub, Gustav January 1976 (has links)
Thesis. 1976. B.S.--Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science. / Microfiche copy available in Archives and Engineering. / by Gustav Laub III. / B.S.
24

Research on the Factors Turning AM Radio to the Digital Future

Chen, Wan- Chen 22 August 2005 (has links)
On 29th February 2000, The Directorate General of Telecommunications, Ministry of Transportation and Communications, announced the result of selection for DAB (Digital Audio Broadcasting) experimental digital broadcasting. From that moment, many FM Radio Stations initiated their DAB digital broadcasting. Compared with FM Radio, AM Radio is slower on initiating digital broadcasting. However, new technology continuously comes out. The integration of media technology has a great influence on the media broadcasting model. The emergence of new media accelerates the decline of traditional media. Earlier emerging than internet, TV and FM Radio industries, how will AM Radio strive for continuance and development? To encourage existing AM Radio in initiating their digital future, the Ministry of Transportation and Communications announced the project of experimental digital broadcasting of IBOC AM and DRM on June 3rd, 2004. It is worth for the research scholars to study how the AM Radio initiates digital broadcasting and what the influential factors are. Therefore, this research is trying to find the factors which turn AM Radio to the digital future, and also discuss what factors will encourage radio enterprenors to initiate digital broadcasting, what kind of digital system is appropriate for AM Radio, and what the situation is for experimental DRM broadcasting in Taiwan. We are trying to find out the factors turning AM Radio to the digital future, and make AM Radio (with declining listening ratio and poor reception quality) improve the performance, as well as create new core value of AM Radio Industry. According to the objective and motivation above-mentioned, we designed and proceeded this research as follows: We started from an investigation on 28 AM Radio Stations in Taiwan to know their needs for digital broadcasting, and then collected data and made statistic analysis based on the questionnaires returned. We also took interviews with professional people assisting in DRM digital broadcasting for AM Radio. Besides, we participated in the World DAB Forum Conference held in Taiwan in this year, and finally went into a conclusion and some suggestions. We found from the information in questionnaires that the factors making AM Radio to initiate digital broadcasting are not precise. However, we know more about how the digital broadcasting is going among AM Radio Stations, from the information collected by interviewing professional people who assist in DRM digital broadcasting for AM Radio. It will bring advantages in competition for AM Radio Stations to initiate digital broadcasting. Thus, it can not wait to turn to digital future. The Radio enterprenors should use technology well and increase additional value. They have to follow the trend, develop new co-operation model, and establish their brand image. They should also enhance on inspection of program contents, and hold success factors. They can increase reception ratio only with fine broadcasting, excellent program contents, good reception quality and perfect marketing strategy. As to the technical people, they need to care about the development on technology, and provide new information for management to make decision. Besides, the policy of government must be precise, in order to encourage Radio enterprenors in initiating digital broadcasting. The above conclusion could be the reference in digital radio research.
25

A proportional timing generator for measuring intermodulation product distortion on television transposers.

Bouwer, Paul Frederick. January 1989 (has links)
Broadcasting authorities presently measure intermodulation distortion by applying a three tone simulation of a composite video and sound signal to the transposer and then measuring the relative amplitude of the major in-band intermodulation product (nominally at vision carrier frequency plus 1,57 MHz in the 625 line I/PAL System) on a spectrum analyser. This method is slow and requires a skilful operator to achieve repeatable results. Furthermore it tests the common RF amplification equipment at one luminance level and one chrominance level and therefore does not subject the transposer equipment to operation over its full range. A new sampling measurement technique has been proposed which overcomes all these problems by selectively mixing, while transmitting a colour bar test pattern, the demodulated output video signal of the frequency transposer with a pulse train coinciding with a particular colour. This thesis describes the design of a very stable proportional timing generator and its application to the measurement of intermodulation distortion on frequency transposers. The timing generator, which locks automatically onto the video signal and produces narrow sampling pulses which coincide accurately with a particular section of each line over a 50°C temperature range, is applicable to all PAL and NTSC TV Systems. / Thesis (Ph.D.)-University of Natal, Durban, 1989.
26

Precoder design and adaptive modulation for MIMO broadcast channels

Huang, Kuan Lun, Electrical Engineering & Telecommunications, Faculty of Engineering, UNSW January 2007 (has links)
Multiple-input multiple-output (MIMO) technology, originated in the 1990s, is an emerging and fast growing area of communication research due to the ability to provide diversity as well as transmission degrees-of-freedom. Recent research focus on MIMO systems has shifted from the point-to-point link to the one-to-many multiuser links due to the ever increasing demand for multimedia-intensive services from users. The downlink of a multiuser transmission is called the broadcast channel (BC) and the reverse many-to-one uplink is termed the multiple access channel (MAC). Early studies in the MIMO BC and the MIMO MAC were mostly information-theoretic in nature. In particular, the characterizations of the capacity regions of the two systems were of primary concerns. The information-theoretic results suggest the optimal uplink detection scheme involves successive interference cancellation while successive application of dirty paper coding at the transmitter is optimal in the downlink channels. Over the past few years, after the full characterizations of the capacity regions, several practical precoders had been suggested to realize the benefits of MIMO multiuser transmission. However, linear precoders such as the zero-forcing (ZF) and the MMSE precoders fall short on the achievable capacity despite their simple structure. Nonlinear precoders such as the ZF dirty paper (ZF-DP) and the the MMSE generalized decision feedback equalizer-type (MMSE-GDFE) precoders demonstrated promising performance but suffered from either restriction on the number of antennas at users, i.e. ZF-DP, or high computational load for the transmit filter, i.e. MMSE-GDFE. An novice MMSE feedback precoder (MMSE-FBP) with low computational requirement was proposed and its performance was shown to come very close to the bound suggested by information theory. In this thesis, we undertake investigation of the causes of the capacity inferiority and come to the conclusion that power control is necessary in a multiuser environment. New schemes that address the power control issue are proposed and their performances are evaluated and compared. Adaptive modulation is an effective and powerful technique that can increase the spectral efficiency in a fading environment remarkably. It works by observing the channel variations and adapts the transmission power and/or rate to counteract the instabilities of the channel. This thesis extends the pioneering study of adaptive modulation on single-input single-output (8180) Gaussian channel to the MIMO BC. We explore various combinations of power and rate adaptions and observe their impact on the system performance. In particular, we present analytical and simulation results on the successiveness of adaptive modulation in maximizing multiuser spectral efficiency. Furthermore, empirical research is conducted to validate its effectiveness in optimizing the overall system reliability.
27

A calibrated phase and amplitude control system for phased-array transmitters /

Charles, Cameron T. January 2006 (has links)
Thesis (Ph. D.)--University of Washington, 2006. / Vita. Includes bibliographical references (leaves 150-155).
28

Codage de l'enveloppe temporelle dans le nerf auditif / Temporal envelope coding of sound in the auditory nerve

Hasselmann, Florian 21 November 2017 (has links)
Contexte : La compréhension de la parole dans le silence est dépendante des mécanismes de codage de l’enveloppe temporelle du signal sonore. Une anomalie du codage (d’origine infectieuse, immunitaire, génétique, tumorale, ou environnementale) entraine irrémédiablement une diminution des performances audiométriques vocales. Les méthodes d’exploration fonctionnelle de la cochlée (potentiels d’action composite du nerf auditif, potentiel évoqués auditifs précoces) utilisent des stimuli sonores simples (clics, bouffées tonales) pour détecter une anomalie de codage des indices temporels. Le but de cette étude était de développer une méthode électrophysiologique capable de mesurer les réponses du nerf auditif à des stimuli modulés en amplitude.Matériel et méthodes : La réponse électrophysiologique du nerf auditif a été mesurée à l’aide d’une électrode placée sur la niche de la fenêtre ronde de la cochlée de gerbilles et de rats vieillissants. Les stimuli acoustiques consistaient en des bandes de bruit de 20 secondes modulées sinusoïdalement en amplitude et centrées sur 4, 8 et 16 kHz. Nous avons étudié le niveau, la profondeur de modulation, la fréquence de modulation et la fréquence porteuse.Résultats : Notre étude sur le modèle de perte sélective neuronale (ouabain) montre que l’analyse des potentiels globaux cochléaires permet de détecter une perte de fibres à basse activité spontanée dans le nerf auditif, résultat important car indétectable (« surdités cachées ») actuellement avec les tests utilisés en routine en clinique (EcoG et PEA) (Batrel, Huet, Hasselmann et al, Plos One 2017). Ensuite, en combinant le stimulus de cette étude avec une fonction sinusoïdale, nous avons développé et validé une méthode pour évaluer la qualité de codage de l’enveloppe par le nerf auditif. Nous avons appliqué cette méthode sur un modèle de vieillissement (rat Sprague-Dawley). Nos résultats suggèrent que le viellissement entraine une modifcation du phénotype des fibres du nerf auditif sans pertes de fibres associées (article Occelli, Hasselmann et al, soumis à eNeuro). Conclusion : Notre travail démontre qu’il est indispensable d’élargir le nombre de techniques d’exploration fonctionnelle de la cochlée car les tests utilisés en routine en clinique ne permettent pas de déceler des déficits subtils d’encodage dans le nerf auditif. La mesure de l’activité soutenue des fibres permet de détecter la perte sélective des neurones à basse activité spontanée, indétectable avec les méthodes classiques. Le changement de phénotype des fibres observé au cours du vieillissement du rat Sprague-Dawley est détectable avec notre méthode alors qu’il ne l’est pas avec le potentiel d’action composite du nerf auditif. / Background: Speech intelligibility in quiet is critically dependent on the temporal envelope of a sound signal. An abnormal coding of this temporal cue (due to infectious, immune, genetic, tumoral or environmental of origin) implies a decrease of speech recognition scores. The current proxy to probe deafness in clinical framework (Compound Action Potential of the auditory nerve, auditory brainstem responses) uses simplistic stimuli (clicks, tone bursts) to detect a such abnormal coding of the temporal cues. The aim of this study was to develop a new electrophysiology method in murins able to measure the auditory nerve responses to amplitude-modulation stimuli.Material and methods: The electrophysiology response of the auditory nerve was recorded using an electrode implanted onto the round window niche on normal-hearing gerbil cochlea and aging rat cochlea. The acoustical stimuli consisted of 20 seconds sinusoidally amplitude-modulated noise-band centered on 4, 8 and 16 kHz. We have studied varying sound level, the modulation depth, the modulation frequency and the carrier frequency.Results: Our study on the selective fiber loss ouabain model show the mass potentials recorded at the round window enable the detection of low spontaneous rate fibers in gerbil auditory nerve. This result is important because the current clinical used tests aren’t enough sensitive to detect a such coding impairment (CAP, ABR) (Batrel, Huet, Hasselmann et al., 2017). Then we combined the stimulus of this previous study with a sinusoidal function to develop a new method to assess the envelope coding by the auditory nerve. We validated this new method. Last, we used our method on an aging model (Sprague-Dawley rat). Our results suggest aging leads to a phenotype change of auditory nerve fibers without associated fiber loss (article Occelli, Hasselmann et al, submitted to eNeuro).Conclusion: Our study shows it’s indispensable to expand the number of tools to probe the cochlea because the current clinical used tests aren’t enough sensitive to detect subtle deficits of encoding in the auditory nerve. The recording of the fiber sustained activity enable to detect the selective loss of low-spontaneous rate neurons. A such loss is undetectable with classical clinical tools. The phenotype change of fibers we observed in aging Sprague-Dawley rats is detectable with our method whereas it’s not using the compound action potential of the auditory nerve.
29

Optimalizace telekomunikačního výukového prostředí / Optimization of telecommunication education environment

Jeřábek, Josef January 2008 (has links)
The intended goal within the scope of this master´s thesis is to get acquainted with the product of EMONA INSTRUMENTS Company. There are two main concepts: the software version TutorTIMS – Advanced and the hardware version TIMS-301. Both concepts were bought into the laboratory, where the following subjects are being lectured: “Access and transport networks” and “Telecommunication network services”. Three laboratory exercises were prepared for both software version and hardware version. Both versions are modular and all designed exercises support independent and creative approach of students. All exercises also consist of standard parts, which are the description of the exercise and exemplary protocol solution. The first exercise is called “amplitude modulation” and is designed as an introductory exercise. Next are a couple of exercises which are designed to be performed on one workplace at the same time. The first of them is focused on practical verification of facts from amplitude shift keying, the second one focuses on link codes. This couple of exercises is the best choice, considering the hardware version of TIMS-301 and at the present time available modules in the lab. Software version is not limited in such way, but it was required to allow performing all of prepared exercises on both versions. Lastly there is a comparison between the software and hardware version and several options for hardware TIMS optimization.
30

Výkonový zesilovač pro pásmo krátkých vln / Shortwave power amplifier

Fiala, Roman January 2016 (has links)
This master’s thesis describes RF power amplifier design. The designed amplifier has been built. The first three chapters outline basics about radio frequency amplifiers. The basic theory needed for amplifier implementation is also described there. In the fourth chapter the power amplifier is designed. The design is based on the theoretical knowledge. Complete amplifier contains RF preamplifier, power amplifier and filters. The OrCAD PSpice, Ansoft Designer SV and EAGLE programs have been used for the design and verification of some sections of circuits. Measurement results of the built amplifier are in the fifth chapter. This thesis contains also the draft for laboratory exercise.

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