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1
Politis, Z. "Environmental perception using CTFM sonar imaging." Thesis, University of Oxford, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.365775.
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Saleem, Sajid. "Frequency-domain equalization for continuous phase modulation." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/50391.
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Continuous phase modulation~(CPM) is a non-linear, constant-envelope modulation scheme with memory, known for its bandwidth and power efficiency. Multi-h CPM uses multiple modulation indices in successive symbol intervals to improve the error performance as compared to single-h CPM~(basic CPM that utilizes only a single modulation index). One of the major applications of multi-h CPM is in aeronautical telemetry systems. Modern aeronautical devices host an increasing number of sensors, which can transmit flight testing data to the ground station. However, this excess data transfer increases the intersymbol interference, and thus channel equalization is required at the receiver. The objective of our research is to propose low-complexity frqeuency-domain equalization~(FDE) techniques for multi-h CPM waveforms. For a modulation scheme with memory, such as CPM, the cyclic constraint on the FDE block necessitates the use of an extra segment of symbols, called intrafix or tail segment. We have used very simple geometric arguments to derive upper and lower bounds on the length of the intrafix in terms of the parameters of the modulation scheme and the Frobenius number. It is concluded that the length of the intrafix for multi-h CPM schemes is typically shorter than those required for single-h modulation schemes. We propose two receiver architectures; one uses a matched filter front end, while the other utilizes a fractional sampling front end. Various simplifications are proposed for each architecture, and the trade-off between receiver complexity and performance is analyzed and verified through detailed simulation studies.
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Zhao, Lu. "Optical transmission of wideband video signals using SWFM." Thesis, University of Manchester, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317775.
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Detwiler, Thomas Frederick. "Continuous phase modulation for high speed fiber-optic links." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42867.
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Fiber-optic networks are continually evolving to accommodate the ever increasing data rates demanded by modern applications and devices. The current state-of-the art systems are being deployed with 100 Gb/s rates per wavelength while maintaining the 50 GHz channel spacing established for 10 Gb/s dense wavelength division multiplexed (DWDM) systems. Phase modulation formats (in particular quadrature phase shift keying - QPSK) are necessary to meet the spectral efficiency (SE) requirements of the application. The main challenge for phase modulated optical systems is fiber nonlinearities, where changes in intensity of the combined optical signal result in changes to the fiber's refractive index. Limiting launch power is the primary means to avoid dramatic intensity fluctuations, a strategy which in turn limits the available signal-to-noise ratio (SNR) within the channel.
Continuous phase modulation (CPM) is a format in which data is encoded in the phase, while the amplitude is constant throughout all transmission (even during transitions between symbols). With the goal of reducing the impact of nonlinearities, the purpose of this research was to identify a set of CPM signals best suited for high speed fiber-optic transmission, and quantify their performance against other formats. The secondary goal was to identify techniques appropriate for demodulation of high speed fiber-optic systems and implement them for simulation and experimental research.
CPM encompasses a number of variable parameters that combine to form an infinite number of unique schemes, each of which is characterized by its own SE, minimum distance, and implementation complexity. A method for computing minimum distance of DWDM-filtered CPM formats is presented and utilized to narrow down to a range of candidate schemes. A novel transmitter design is presented for CPM signal generation, as well as a number of novel reception techniques to achieve proper demodulation of the CPM signal from the coherent optical receiver. Using these methods, the identified range of candidate schemes was compared in simulation to the conventional QPSK format, showing that some modest gain can be expected from CPM.
Through these and other simulations, it is revealed that fiber nonlinearities depend on the aggregate sum of all wavelengths rather than the imposition of each separate carrier on its neighbors. Therefore the constant envelope of CPM does not directly impact the nonlinearities since multiple carriers will photonically interfere and result in intensity fluctuations regardless of modulation format. Additionally, dispersive effects in fiber decompose the underlying channels so that the intensity throughout propagation is nearly Gaussian distributed, regardless of format. The benefits gained from CPM are thus limited to schemes that attain a higher minimum distance than alternative formats (in the given channel passband), and for optically compensated links in which low dispersion is maintained throughout the fiber link.
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Day, James V. "Construction of a continuous wave frequency modulation sensitive laser radar for use in target identification." Thesis, Monterey, California. Naval Postgraduate School, 1997. http://hdl.handle.net/10945/8147.
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Approved for public release; distribution is unlimitedThis thesis covers the theory, design and construction of a continuous wave (CW) frequency modulation sensitive laser radar. Using a commercially available CO2 laser, optics and electronics, a CW frequency modulation sensitive laser radar was constructed and tested under laboratory conditions. The theory of each component in the laser radar is covered as well as the configuration and design of the radar. Design of a target that enabled measurement of the laser radar's capabilities was also completed. The laser radar was able to accurately measure a target's vibrational frequency and amplitude for amplitudes greater than 40 nim The theoretical range of the designed laser radar is over 6 km. An improved optical design that allows a theoretical range of over 9 km is also presented. Applications of target identification are discussed.
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Lovejoy, David. "A Technical Comparison of Frequency and Phase Modulation Relative to PCM Data Transmission Systems." International Foundation for Telemetering, 1987. http://hdl.handle.net/10150/615334.
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International Telemetering Conference Proceedings / October 26-29, 1987 / Town and Country Hotel, San Diego, CaliforniaDirect experience in the design and developement of airborne telemetry systems utilizing both principles of modulation. System level analysis of receiver phase coherency, bit sync error codes, data band width, transmission efficiency and overall system complexity. High reliability, miniaturized packaging and HI-G survivability will be stressed as well as illustrated.
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Zheng, Gang. "Development of advanced birefringent fibre force sensor systems based on frequency modulation continuous wave (FMCW) technology." Thesis, Glasgow Caledonian University, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.337411.
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Gendron, Paul John. "A comparison of digital beacon receiver frequency estimators." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-09292009-020307/.
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Slagle, Jonathan E. "Degenerate Frequency Two Beam Coupling in Organic Media Via Phase Modulation." University of Dayton / OhioLINK, 2014. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1417798867.
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Dhuness, Kahesh. "An offset modulation method used to control the PAPR of an OFDM transmission." Thesis, University of Pretoria, 2012. http://hdl.handle.net/2263/27258.
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Orthogonal frequency division multiplexing (OFDM) has become a very popular method for high-data-rate communication. However, it is well known that OFDM is plagued by a large peak-to-average power ratio (PAPR) problem. This high PAPR results in overdesigned power amplifiers, which amongst other things leads to inefficient amplifier usage, which is undesirable. Various methods have been recommended to reduce the PAPR of an OFDM transmission; however, all these methods result in a number of drawbacks. In this thesis, a novel method called offset modulation (OM-OFDM) is proposed to control the PAPR of an OFDM signal. The proposed OM-OFDM method does not result in a number of the drawbacks being experienced by current methods in the field. The theoretical bandwidth occupancy and theoretical bit error rate (BER) expression for an OM-OFDM transmission is derived. A newly applied power performance decision metric is also introduced, which can be utilised throughout the PAPR field, in order to compare various methods. The proposed OM-OFDM method appears to be similar to a well-known constant envelope OFDM (CE-OFDM) transmission. The modulation, structural and performance differences between an OM-OFDM and a CE-OFDM method are discussed. By applying the power performance decision metric, the OM-OFDM method is shown to offer significant performance gains when compared to CE-OFDM and traditional OFDM transmissions. In addition, the OM-OFDM method is able to accurately control the PAPR of a transmission for a targeted BER. By applying the power performance decision metric and complementary cumulative distribution function (CCDF), the proposed OM-OFDM method is shown to offer further performance gains when compared to existing PAPR methods, under frequency selective fading conditions. In this thesis, the OM-OFDM method has been combined with an existing active constellation extended (ACE) PAPR reduction method. To introduce a novel method called offset modulation with active constellation extension (OM-ACE), to control the PAPR of an OFDM signal. The theoretical BER expression for an OM-ACE transmission is presented and validated. Thereafter, by applying the decision metric and CCDF, the OM-ACE method is shown to offer performance improvements when compared to various PAPR methods. The use of OM-OFDM for cognitive radio applications is also investigated. Cognitive radio applications require transmissions that are easily detectable. The detection characteristics of an OM-OFDM and OFDM transmission are studied by using receiver operating characteristic curves. A derivation of a simplified theoretical closed-form expression, which relates the probability of a missed detection to the probability of a false alarm, for an unknown deterministic signal, at various signal-to-noise ratio (SNR) values is derived and validated. Previous expressions have been derived, which relate the probability of a missed detection to the probability of a false alarm. However, they have not been presented in such a generic closed-form expression that can be used for any unknown deterministic signal (for instance OFDM and OM-OFDM). Thereafter, an examination of the spectrum characteristics of an OM-OFDM transmission indicates its attractive detection characteristics. The proposed OM-OFDM method is further shown to operate at a significantly lower SNR value than an OFDM transmission, while still offering better detection characteristics than that of an OFDM transmission under Rician, Rayleigh and frequency selective fading channel conditions. In addition to its attractive PAPR properties, OM-OFDM also offers good detection characteristics for cognitive radio applications. These aspects make OM-OFDM a promising candidate for future deployment.Thesis (PhD)--University of Pretoria, 2012.
Electrical, Electronic and Computer Engineering
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Rahbari, Hanif. "Obfuscation of Transmission Fingerprints for Secure Wireless Communications." Diss., The University of Arizona, 2016. http://hdl.handle.net/10150/612371.
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Our world of people and objects is on the verge of transforming to a world of highly-interconnected wireless devices. Incredible advances in wireless communications, hardware design, and power storage have facilitated hasty spread of wireless technologies in human life. In this new world, individuals are often identified and reached via one or multiple wireless devices that they always carry (e.g., smartphones, smart wearable, implantable medical devices, etc.), and their biometrics identities are replaced by their digital fingerprints. In near future, vehicles will be controlled and monitored via wireless monitoring systems and various physical objects (e.g., home appliance and retail store items) will be connected to the Internet. The list of these changes goes on. Unfortunately, as different aspects of our lives are being immerged in and dependent to wireless devices and services, we will become more vulnerable to wireless service/connection interruptions due to adversarial behavior and our privacy will become more potent to be exposed to adversaries. An adversary can learn the procedures of a wireless system and analyze its stages, and accordingly, launch various attacks against the operations of the system or the privacy of the people. Existing data confidentiality and integrity services (e.g., advanced encryption algorithms) have been able to prevent the leakage of users' messages. However, in wireless networks, even when upper-layer payloads are encrypted, the users' privacy and the operation of a wireless network can be threatened by the leakage of transmission attributes at the physical (PHY) layer. Examples of these attributes are payload size, frequency offset (FO), modulation scheme, and the transmission rate. These attributes can be exploited by an adversary to launch passive or active attacks. A passive attacker may learn about the interests, sexual orientation, political views, and patentable ideas of the user through analyzing these features, whereas an active attacker exploits captured attributes to launch selective packet jamming/dropping and disrupt wireless services. These call for novel privacy preserving techniques beyond encryption. In this dissertation, we study the vulnerability of current wireless systems to the leakage of transmission attributes at the PHY layer and propose several schemes to prevent it. First, we design and experimentally demonstrate with USRPs an energy-efficient and highly disruptive jamming attack on the FO estimation of an OFDM system. OFDM is the core multiplexing scheme in many modern wireless systems (e.g., LTE/5G and 802.11a/n/ac) and is highly susceptible to FO. FO is the difference in the operating frequencies of two radio oscillators. This estimation is done by the receiver using the publicly-known frame preamble. We show that the leakage of FO value via the preamble can facilitate an optimally designed jamming signal without needing to know the channel between the transmitter and the legitimate receiver. Our results show that the jammer can guarantee a successful attack even when its power is slightly less than the transmitter's power. We then propose four mitigation approaches against the proposed FO attack. Next, we consider certain transmission attributes that are disclosed via unencrypted PHY/MAC headers. Example of these attributes are payload size, transmission rate, and MAC addresses. Beyond unencrypted headers, the adversary can estimate the frame size and transmission rate through identifying the payload's modulation scheme and measuring the transmission time. To prevent the leakage of these attributes, we propose Friendly CryptoJam scheme, which consists of three components: First, a modulation-aware encryption scheme to encrypt the headers. Second, an efficient modulation obfuscation techniques. Specifically, the proposed modulation obfuscation scheme embeds the modulation symbols of a frame's payload into the constellation of the highest-order modulation scheme supported by the system. Together with effective PHY/MAC header encryption at the modulation level, the proposed obfuscation scheme hides the transmission rate, payload size, and other attributes announced in the headers while avoiding any BER performance loss. Compared with prior art, Friendly CryptoJam enjoys less complexity and less susceptibility to FO estimation errors. The third component is a novel PHY-level identification method. To facilitate PHY/MAC header encryption when a MAC layer sender identifier cannot be used (e.g., due to MAC address encryption), we propose two preamble-based sender identification methods, one for OFDM and one for non-OFDM systems. A sender identifier is special message that can be embedded in the frame preamble. The extent of the applications of our embedding scheme goes beyond identifier embedding and include embedding part of the data frame, the sender's digital signature, or any meta-data that the sender provides. Our message embedding method can further be used to mitigate the FO estimation attack because the jammer can no longer optimize its jamming signal with respect to a fixed preamble signal. In addition, we considered friendly jamming technique in a multi-link/hop network to degrade the channels of the eavesdroppers and prevent successful decoding of the headers, while minimizing the required jamming power by optimally placing the friendly jamming devices.
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Akangol, Mehmet. "Target Detection By The Ambiguity Function Technique And The Conventional Fourier Transform Technique In Frequency Coded Continuous Wave Radars." Master's thesis, METU, 2005. http://etd.lib.metu.edu.tr/upload/12606766/index.pdf.
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Continuous Wave (CW) radars are preferred for their low probability of intercept by the other receivers. Frequency modulation techniques, the linear frequency modulation (LFM) technique in particular, are commonly used in CW radars to resolve the range and the radial velocity of the detected targets. The conventional method for target detection in a linear FMCW radar makes use of a mixer followed by a low-pass filter whose output is Fourier transformed to get the range and velocity information. In this thesis, an alternative target detection technique based on the use of the Ambiguity Function (AF) will be investigated in frequency modulated CW radars. Results of the AF-based technique and the conventional Fourier-based technique will be compared for different target detection scenarios.
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吳萬雄 and Man-hung Ng. "Bandwidth-efficient pilot-symbol-aided techniques for fading estimation in multipath fading channels." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31242212.
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Franklin, Daniel Robert. "Enhancements to channel models, DMT modulation and coding for channels subject to impulsive noise." School of Electrical, Computer & Telecommunications Engineering - Faculty of Informatics, 2007. http://ro.uow.edu.au/theses/18.
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DMT modulation is an OFDM-based modulation scheme used in ADSL and proposed for various other high-speed broadband access systems. Existing mathematical models for transmission lines make a number of simplistic assumptions about the distribution of noise, in particular, the assumption that impulsive noise originates at either end of the transmission line. It is therefore desirable to improve the accuracy of the transmission-line model to allow better prediction of broadband modem performance, and to further improve the bit-allocation algorithms and equaliser designs used in DMT-based modems. This Thesis presents a new channel model particularly well-suited for simulation of high-speed digital subscriber line systems. The model extends a commonly-used physical channel model by distributing the points of noise ingress along the physical length of the transmission line. Simulation results are presented for a highspeed multicarrier modem operating on channels modelled with both the conventional and new models. Comparison with the same modem operating over a real channel demonstrates that the new model provides a better estimate of the bit error rates and temporal error distribution expected on actual telephone lines than is possible with the conventional model. A number of improvements to modulation and coding schemes for DMT modems are also presented in this Thesis, including a robust frequency-domain decision feedback equaliser, a new algorithm for allocating bits to sub-carriers based on a measurement of per-carrier BER, and a technique for encoding data with fractional numbers of bits ii Abstract iii per symbol, thereby providing additional channel capacity.
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Hamze, Mohamad. "Study of different SOA structures impact on the transmission of IMDD OOFDM signals." Thesis, Brest, 2015. http://www.theses.fr/2015BRES0026/document.
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Le travail de thèse porte sur une étude d'impact de différentes structures SOA sur la transmission optique de signaux OFDM modulés en intensité et reçus en détection directe (IMDD-OOFDM), dans le cadre des réseaux d'accès de nouvelle génération (σGPτσ). Dans la première partie du travail, nous avons d’abord validé expérimentalement la modélisation d’un RSτA sur une large plage d’utilisation. Ce modèle a ensuite été implémenté dans le cadre d'une plate-forme de co-simulation pour les systèmes de transmission IMDD-OOFDM et pour la conversion en longueur d'onde de signaux OOFDM avec une validation expérimentale. Une analyse approfondie des performances de transmission a été ensuite menée en termes de puissance optique et de longueur d’onde injectées, de longueur de fibre, de l’émission spontanée amplifiée (ASE), de la bande passante électrique et des non-linéarités du RSτA. Nous avons notamment montré théoriquement qu’une capacité minimale de transmission de 8,9 Gb/s sur 100 km pouvait être atteinte sur une plage de 100 nm avec le RSOA utilisé et avec l’aide d’une modulation adaptative (AMττFDM). Nous avons également démontré expérimentalement, pour la première fois à notre connaissance, la conversion de longueur d'onde de signaux optiques OOFDM-16QAM sur une plage de 70 nm en utilisant l'effet XGM du RSOA. Dans la seconde partie, nous avons développé la modélisation de plusieurs structures de SOA : un SOA à îlots quantiques (QD SOA), un SOA bi-électrodes et deux SOA cascadés en configuration contra-propagative. Nous avons étudiés leurs performances en transmission à l’aide de la modulation AMττFDM. Nous avons montré que ces structures présentent une capacité de transmission allant jusqu’à 30 Gb/s avec des distances de transmission jusqu'à 60 km. Nous avons montré également que le QD-SOA présente de meilleures performances en termes de capacité de transmission pour des distances allant jusqu'à 140 km en comparaison avec les deux autres configurationsThe thesis work deals with study of different SOA structures impact on the transmission of intensity modulation and direct detection OFDM signals in the context of the next generation access networks. In the first part of the work, we have experimentally validated a comprehensive wideband RSOA field model. It was the nused as part of a co-simulation platform for IMDD-OOFDM and OOFDM wavelength conversion transmission systems. Thanks to this co-simulation platform that presents good agreement with the measurement, and our experimental setup, we analyze the transmission performance in terms of optical input power, fiber length, ASEnoise, electrical bandwidth and RSOA nonlinearities. We showed by simulation that an AMOOFDM signal transmission over a 100 nm wavelength range with a minimum transmission capacity of 8.9 Gb/s for fiber lengths up to 100 km can be reached. Finally, we experimentally demonstrated, for the first time to the best of our knowledge, the feasibility of performing wave length conversion over 70 nm of OOFDM-16QAM optical signals using the XGM effect in an RSOA. In the second part of this work we develop a simplified quantum dot –SOA and two electrode SOAintensity modulator models and study their effect on a numerical OFDM IMDD transmission system, we also study a two cascaded SOA in a counter propagating configuration as an intensity modulator. We find that for the three configurations we can achieve a high transmission capacity of around 30 Gb/s for transmission distances up to 60 Km, we also find that the QD-SOA will have the best performance in terms of transmission capacity for distances up to 140 Km in comparison with the two other SOA configurations
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Chayot, Romain. "Synchronisation, détection et égalisation de modulation à phase continue dans des canaux sélectifs en temps et en fréquence." Thesis, Toulouse, INPT, 2019. http://oatao.univ-toulouse.fr/24188/1/Chayot_Romain.pdf.
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Si les drones militaires connaissent un développement important depuis une quinzaine d’année, suivi depuis quelques années par les drones civiles dont les usages ne font que se multiplier, en réalité les drones ont un siècle avec le premier vol d’un avion équipé d’un système de pilotage automatique sur une centaine de kilomètre en 1918. La question des règles d’usage des drones civiles sont en cours de développement malgré leur multiplication pour des usages allant de l’agriculture, à l’observation en passant par la livraison de colis. Ainsi, leur intégration dans l’espace aérien reste un enjeu important, ainsi que les standards de communication avec ces drones dans laquelle s’inscrit cette thèse. Cette thèse vise en effet à étudier et proposer des solutions pour les liens de communications des drones par satellite.L’intégration de ce lien de communication permet d’assurer la fiabilité des communications et particulièrement du lien de Commande et Contrôle partout dans le monde, en s’affranchissant des contraintes d’un réseau terrestre (comme les zones blanches). En raison de la rareté des ressources fréquentielles déjà allouées pour les futurs systèmes intégrant des drones, l’efficacité spectrale devient un paramètre important pour leur déploiement à grande échelle et le contexte spatiale demande l’utilisation d’un système de communication robuste aux non-linéarités. Les Modulations à Phase Continue permettent de répondre à ces problématiques. Cependant, ces dernières sont des modulations non-linéaire à mémoire entraînant une augmentation de la complexité des récepteurs. Du fait de la présence d’un canal multi-trajet (canal aéronautique par satellite), le principal objectif de cette thèse est de proposer des algorithmes d’égalisation (dans le domaine fréquentiel pour réduire leur complexité) et de synchronisation pour CPM adaptés à ce concept tout en essayant de proposer une complexité calculatoire raisonnable. Dans un premier temps, nous avons considéré uniquement des canaux sélectifs en fréquence et avons étudier les différents égaliseurs de la littérature. En étudiant leur similitudes et différences, nous avons pu développer un égaliseur dans le domaine fréquentiel qui proposant les mêmes performances a une complexité moindre. Nous proposons également des méthodes d’estimation canal et une méthode d’estimation conjointe du canal et de la fréquence porteuse. Dans un second temps nous avons montré comment étendre ces méthodes à des canaux sélectifs en temps et fréquence permettant ainsi de conserver une complexité calculatoire raisonnable.
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Ajaz, Haroon. "Study of fade and inter-fade durations in Ku- and Ka- band frequencies using OLYMPUS satellite beacons." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-12042009-020112/.
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Laster, Jeff D. "Frequency scaling of rain attenuation on satellite links in the Ku/Ka-bands using OLYMPUS satellite data." Thesis, This resource online, 1993. http://scholar.lib.vt.edu/theses/available/etd-06162009-063211/.
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Culha, Onur. "Noncoherent Differential Demodulation Of Cpm Signals With Joint Frequency Offset And Symbol Timing Estimation." Master's thesis, METU, 2011. http://etd.lib.metu.edu.tr/upload/12613729/index.pdf.
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In this thesis, noncoherent differential demodulation of CPM signals with joint
carrier frequency offset and symbol timing estimation is investigated. CPM is very
attractive for wireless communications owing to major properties: good spectral
efficiency and a constant envelope property. In order to demodulate the received
CPM signal differentially, the symbol timing and the carrier frequency offset have
to be estimated accurately. There are numerous methods developed for the
purpose. However, we have not encountered studies (which are based on autocorrelation
estimation and hence suitable for blind synchronization) that give
expectable performance for both M-ary and partial response signaling. Thus, in
this thesis we analyze a feedforward blind estimation scheme, which recovers the
symbol timing and the frequency offset of M-ary CPM signals and partial response
CPM signals. In addition, we surveyed low complexity symbol detection methods
for CPM signals. Reduced state Viterbi differential detector incorporated to the
joint frequency offset and symbol timing estimator is also examined. The
performance of the examined demodulator scheme is assessed for the AWGN
channel by computer simulations.
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Novák, Pavel. "Úzkopásmový PLC modem." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-242170.
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The theses is focused on the use of PLC technology. The aim of the thesis is creating device which communicates in a narrowband transmission frequency band. Transmission of communication between plc elements runs through the low voltage distribution network. The frequency and phase modulations are used in order to change the character of data signal. Transmitter and receiver parameters are subjects to the CENELEC standard. The theses gives more attention to the area of hardware build communication element rather than the area of programming.
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D'Souza, Mark Francis. "Residential Microwave Oven Interference on Bluetooth Data Performance." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/31935.
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This thesis investigates the interference potential of microwave ovens to Bluetooth data communication. Interference experiments are conducted in the CWTâ s Bluetooth lab, using CSRâ (Cambridge Silicone Radio) Bluetooth radios and a Tektronicsâ Protocol Analyzer to record packet transmissions between the master and slave units.
A novel, â quasi-real timeâ spectral measurement concept is developed to take radio frequency measurements. A LabView program enables a spectrum analyzer to download oven spectral data onto a computer via the instrumentâ s serial port. From this data, three-dimensional plots of microwave radiated power levels versus ISM band frequencies over time periods are produced for different microwave ovens. These plots are compared with the results of interference experiments to explain Bluetooth packet errors.
In addition to causing packet errors, emitted oven power levels at certain frequencies are sometimes strong enough to cause data packets to be lost (dropped) as they are transmitted over the air. This is a major problem since the Protocol Analyzer does not â seeâ these packets and cannot record the transmissions during an experiment. These lost packets can be accounted for if the frequency hopping scheme of the communicating Bluetooth devices is know prior to data transmission. Bluetoothâ s Frequency Hop Scheme is coded in Matlab for the purpose of predicting a data transmissionâ s hopping sequence. The lost packets on each Bluetooth channel are counted by subtracting the Analyzerâ s recorded number of data transmissions per channel from the total number of transmissions per channel predicted by Matlab.
A method is devised to calibrate the Bluetooth receiver and the spectrum analyzer is used to measure the received power level of Bluetooth signals on a particular frequency (channel). The number of packet errors on a channel is determined from the channelâ s C/I (carrier-to-interference ratio). If a channelâ s C/I level falls below the calculated C/I threshold at any instant of time due to oven operation, the packet transmitted at that instant is likely in error. A Matlab program estimates the number of packet errors per channel by counting the number of times the C/I of a channel falls below itâ s threshold value. The predicted number of packet errors is compared with the measured packet errors from experiments to yield extremely good results.
Various oven-interference experiments are conducted in a small building, a large office environment and outdoors. For each experiment, the number of occurrences of transmitted data is plotted for each Bluetooth channel. Composite Excel bar graphs, created from this data, are compared with the oven spectral plots to describe an ovenâ s effect on Bluetooth transmission.
It is determined that different ovens cause packet errors on specifically different channels, in addition to channels 52-54 around the ovenâ s 2450 MHz center operating frequency. The interference experiments suggest that placing an oven a radius of 10 m away from Class I (devices in a piconet will not affect data transmission).Master of Science
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Kim, Eung Jung. "Highly efficient supply modulator for mobile communication systems." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/41058.
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Switching frequency modulation techniques, an inductor current sensing circuit for fast switching converter, and a dual converter are proposed, and the simulation results and experimental results are drawn. The experimental results for monotonic and pseudo-random modulation techniques show that the switching noise peak was effectively reduced as much as -19 dBc. The inductor current sensing circuit accurately tracks the output current of the switching converter that switches up to 30MHz. This current sensing circuit is used to drive the slow converter in the dual converter. The dual converter consists of a fast converter and a slow converter. The fast converter provides only the high frequency conponents in the output current, and the slow converter provides the majority portion of the output current with a higher efficiency. Therefore, the dual converter can have a fast transient response without sacrificing its efficiency. All chips are fabricated in a standard CMOS 0.18um process.
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Meier, Stephan. "System Aspects and Modulation Strategies of an HVDC-based Converter System for Wind Farms." Doctoral thesis, Stockholm : Skolan för elektro- och systemteknik, Kungliga Tekniska högskolan, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-10267.
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Long, Shihe. "Modélisation du canal intra-bâtiment et transmission haut-débit pour les communications optiques dans le spectre visible." Thesis, Ecole centrale de Marseille, 2016. http://www.theses.fr/2016ECDM0005.
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Les communications optiques dans le spectre visible (VLC pour Visible-Light Communications) ont attiré une attention particulière depuis quelques années en tant qu'une solution prometteuse pour les réseaux sans fil à très haut-débit dans les milieux intra-bâtiment. Ainsi, cette technique exploite l'infrastructure d’éclairage basée sur les diodes électroluminescentes (LED) pour la transmission de l'information. Pour cette raison, elle offre de nombreux avantages, comparée aux techniques « classiques » basées sur les transmissions radiofréquences (RF), tels que l'existence d'une grande largeur de bande non réglementée, une sécurité de transmission intrinsèque et une immunité aux interférences électromagnétiques.Les principales contraintes liées à l'établissement d'une transmission VLC à très haut-débit dans ce contexte sont la propagation en trajets multiples et les caractéristiques non-idéales des LEDs commerciales, dites « blanches ». L'objectif de cette thèse est d'étudier l'impact réel de ces contraintes sur la transmission des données et de proposer des solutions efficaces de traitement du signal pour atténuer leurs effets. Nous commençons par étudier la réponse impulsionnelle du canal VLC grâce à l'élaboration d'un outil de simulation efficace. Nous évaluons ensuite la sélectivité en fréquence du canal de propagation en considérant différents critères, tels que la réponse fréquentielle, l'étalement temporelle du canal et le rapport signal à interférences. Dans un deuxième temps, compte tenu de la possibilité de la sélectivité en fréquence du canal et aussi la limitation de la bande passante des LEDs, nous étudions la pertinence de l'emploi de différentes techniques de transmission de signaux, notamment celle de l'OFDM optique (pour Orthogonal Frequency-Division Multiplexing) afin de garantir des débits de transmission compétitifs avec la RF. Etant donné le facteur de crête ou PAPR (pour Peak-to-Average Power Ratio) élevé des signaux modulés en OFDM et la dynamique limitée des LEDs, nous proposons ensuite un nouveau schéma de transmission basé sur la modulation CAP (pour Carrier-less Amplitude and Phase) en plus de l'égalisation dans le domaine fréquentiel (FDE pour Frequency-Domain Equalization) au niveau du récepteur. Nous analysons les performances des liaisons VLC utilisant cette technique et les comparons à l'OFDM optique, en prenant particulièrement en compte la non-linéarité des LEDs. Enfin, nous démontrons l'intérêt de l'utilisation du schéma de transmission CAP-FDE à travers des résultats expérimentauxVisible Light Communications (VLC) have attracted particular attention in the research community since a few years as a promising solution for high-speed indoor wireless networks. By exploiting the existing solid-state light-emitting diode (LED) lighting infrastructure, VLC offer numerous advantages such as a large unlicensed bandwidth, transmission security, and immunity to electro-magnetic interference compared to their radiofrequency counterparts. Within the context of indoor VLC, the multipath propagation channel and the non-ideal characteristics of the commercial white LEDs cause the main limitations for achieving high data-rate transmission. The objective of this thesis is to investigate the true impact of these limitations on the data transmission and to propose efficient signal processing solutions to mitigate their adverse effects. We start by the study of the indoor VLC channel impulse response by developing an efficient simulation tool. We then consider evaluating the channel frequency selectivity through different metrics. Next, given the potentially frequency-selective channel and the limited modulation bandwidth of the LEDs, we investigate the suitability of employing different signal transmission techniques including optical orthogonal frequency-division multiplexing (O-OFDM) in order to achieve high data-rate transmission. Given the high peak-to-average power ratio (PAPR) of O-OFDM signals and the limited dynamic range of the LEDs, we then propose a novel transmission scheme, which consists of using carrier-less amplitude and phase (CAP) modulation together with frequency domain equalization (FDE) at the receiver. We analyze the performance of the VLC link using this technique and compare it with the O-OFDM schemes, especially by taking the non-linear characteristics of the LED into account. Lastly, we demonstrate the merits of using the CAP-FDE transmission scheme via some experimental results
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Cui, Xian. "Efficient radio frequency power amplifiers for wireless communications." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1195652135.
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Bou, Sleiman Joyce. "Terahertz imaging and spectroscopy : application to defense and security." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0077/document.
Full textAbstract:
Le but de ce travail est de quantifier le potentiel et les capacités de la technologie térahertz à contrôler des colis afin de détecter les menaces telles que les armes et les explosifs, sans avoir besoin d'ouvrir le colis.Dans cette étude, nous présentons la spectroscopie térahertz résolue en temps et l'imagerie multi-spectrale pour la détection des explosifs. Deux types d’explosifs, ainsi que leurs mélanges binaires sont analysés. En raison de la complexité de l'extraction des informations face à tels échantillons, trois outils de chimiométrie sont utilisés: l’analyse en composantes principales (ACP), l'analyse des moindres carrés partiels (PLS) et l'analyse des moindres carrés partiels discriminante (PLS-DA). Les méthodes sont appliquées sur des données spectrales térahertz et sur des images spectrales pour : (i) décrire un ensemble de données inconnues et identifier des similitudes entre les échantillons par l'ACP ; (ii) créer des classes, ensuite classer les échantillons inconnus par PLS-DA ; (iii) créer un modèle capable de prédire les concentrations d’un explosif, à l'état pur ou dans des mélanges, par PLS.Dans la deuxième partie de ce travail, nous présentons l'imagerie par les ondes millimétriques pour la détection d'armes dans les colis. Trois techniques d'imagerie différentes sont étudiées : l'imagerie passive, l’imagerie active par des ondes continues (CW) et l’imagerie active par modulation de fréquence (FMCW). Les performances, les avantages et les limitations de chacune de ces techniques, pour l’inspection de colis, sont présentés. En outre, la technique de reconstruction tomographique est appliquée à chacune de ces trois techniques, pour visualiser en 3D et inspecter les colis en volume. Dans cet ordre, un algorithme de tomographie spécial est développé en prenant en considération la propagation gaussienne de l'ondeThe aim of this work is to demonstrate the potential and capabilities of terahertz technology for parcels screening and inspection to detect threats such as weapons and explosives, without the need to open the parcel.In this study, we first present terahertz time-domain spectroscopy and spectral imaging for explosives detection. Two types of explosives as well as their binary mixture is analyzed. Due to the complexity of extracting information when facing such mixtures of samples, three chemometric tools are used: principal component analysis (PCA), partial least square analysis (PLS) and partial least squares-discriminant analysis (PLS-DA). The analyses are applied to terahertz spectral data and to spectral-images in order to: (i) describe a set of unknown data and identify similarities between samples by PCA; (ii) create a classification model and predict the belonging of unknown samples to each of the classes, by PLS-DA; (iii) create a model able to quantify and predict the explosive concentrations in a pure state or in mixtures, by PLS.The second part of this work focuses on millimeter wave imaging for weapon detection in parcels. Three different imaging techniques are studied: passive imaging, continuous wave (CW) active imaging and frequency modulated continuous wave (FMCW) active imaging. The performances, the advantages and the limitations of each of the three techniques, for parcel inspection, are exhibited. Moreover, computed tomography is applied to each of the three techniques to visualize data in 3D and inspect parcels in volume. Thus, a special tomography algorithm is developed by taking in consideration the Gaussian propagation of the wave
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Park, Cheol Hee. "Frequency domain processing techniques for continuous phase modulation." Thesis, 2010. http://hdl.handle.net/2152/ETD-UT-2010-12-2297.
Full textAbstract:
The continuous phase modulation (CPM) has a constant envelope and compact output power spectrum that makes it a promising underlying technology for power and spectrum efficient broadband wireless communications. However, high implementation complexity (especially the complexity of the receiver) required to deal with the phase memory and inter-symbol interference has impeded its adoption for broadband wireless communications, and only a few simple CPM modulation schemes have mainly been used, e.g. binary MSK and GMSK. Thus, research on efficient CPM transceivers to reduce the computational and hardware complexity is important. The major contribution of this dissertation is the development of novel frequency domain processing techniques and transceiver strategies to improve power and spectral efficiency, and reduce the complexity of CPM modulation schemes. First, this dissertation presents simplified frequency domain receiver structures and decoding schemes in the frequency domain for binary and M-ary CPM block transmission. The frequency domain receivers utilize parallel and serial structures with frequency domain processing which considerably reduces hardware and computational complexity compared to conventional time-domain processing. In addition, the decoding schemes in the frequency domain eliminate the controlled phase memory through frequency domain phase equalization instead of maximum-likelihood sequential decoders, e.g. Viterbi decoders. Second, frequency domain channel estimation schemes for CPM block transmission are presented, which adopt superimposed training signals to achieve bandwidth and power efficiency while reducing the complexity. In these schemes, the proposed frequency domain channel estimation uses the superimposed training signals as a reference signal to reduce the throughput loss caused by conventionally multiplexed training signals. Superimposed training signal design is presented, and the trade-off between bandwidth efficiency and power efficiency is also analyzed. Third, block transmission schemes and frequency domain equalization methods for CPM are proposed, which consider linear processing instead of conventional decomposition-based processing. The schemes of frequency domain linear processing avoid the complexity overhead (both in computation and hardware) of conventional orthogonal- or Laurent decomposed-based equalizers. Finally, this dissertation extends CPM block transmission and frequency domain equalization to phase-coded (time-varying modulation index) CPM, which shows better error performance and bandwidth efficiency than fixed modulation index CPM's.text
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Ojha, Anuj Raj. "Trellis coding on multi-amplitude continuous phase frequency shift keying /." 2007. http://proquest.umi.com/pqdweb?did=1453189151&sid=12&Fmt=2&clientId=10361&RQT=309&VName=PQD.
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CHANG, WEN-BIN, and 張文彬. "Research and Application Unmanned Ground Vehicle for Near range Frequency Modulation Continuous Wave." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/64473024974837318717.
Full textAbstract:
碩士國防大學理工學院
電子工程碩士班
103
This study uses Crawler Type Unmanned Ground Vehicle. It features on the Off-road properties. It has advantages on moving in the obstacle environment. It combines the Frequency Modulation Continuous Wave (FMCW) Radar which allows the vehicle to conquer such obstacle environment by detecting and avoiding the obstacles.The conventional motion of UGV is using the Global Positioning System (GPS) for positioning and planning the path. However, such method would be unable to immediately identify the obstacles on the path, resulting in the damages on the vehicle. We use the FMCW Radar to immediately detect and scan the obstacles, in order to let the UGV to identify the size and relative distance of the obstacle. The result shall be able to remedy the incapability of immediate identification in GPS.The application of FMCW Radar does not only remedy the incapability of immediate identification in GPS. If we combine these two systems together, we shall be able to use the detection result of the FMCW Radar to build up a map of obstacles with the GPS coordinate system.The result of this study shall be able to provide a progressed path planning. Such result shall be applied to the reconnaissance, search and rescue and transport on unknown environment. In the future, it can be also combined with other sensors to form a multifunctional vehicle.
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"Applications of optical frequency shift keying modulation format in optical networks." 2004. http://library.cuhk.edu.hk/record=b5891924.
Full textAbstract:
Deng Ning.Thesis (M.Phil.)--Chinese University of Hong Kong, 2004.
Includes bibliographical references (leaves 62-65).
Abstracts in English and Chinese.
ABSTRACT --- p.iii
摘要 --- p.v
Chapter 1 --- BACKGROUND AND INTRODUCTION --- p.1
Chapter 1.1 --- Optical Frequency-Shift Keying (FSK) --- p.1
Chapter 1.1.1 --- Basic concepts and research hotspots of optical FSK --- p.1
Chapter 1.1.2 --- Optical FSK Transmitter and Receiver --- p.3
Chapter 1.2 --- Wavelength Division Multiplexing Optical Passive Networks --- p.8
Chapter 1.3 --- Optical Label Switching (OLS) Networks --- p.10
Chapter 1.4 --- Thesis Contribution and Organization --- p.11
Chapter 2 --- DATA RE-MODULATION ON DOWNSTREAM OPTICAL FSK SIGNALS IN WDM-PONS --- p.12
Chapter 2.1 --- overview of related works --- p.12
Chapter 2.2 --- PON ARCHITIiCTURE USING DOWNSTREAM OPTICAL FSK SIGNALS --- p.13
Chapter 2.3 --- CLS PON DEMONSTRATION USING THREE DIFFERENT OPTICAL FSK TRANSMITTERS --- p.14
Chapter 2.3.1 --- With an optical FSK transmitter based on direct modulation in a DFB laser --- p.14
Chapter 2.3.2 --- With an optical FSK transmitter based on complementary intensity modulation --- p.17
Chapter 2.3.3 --- With our proposed optical FSK transmitter based on phase modulation --- p.21
Chapter 2.4 --- System Performance by Using Phase Modulation Based FSK Transmitter…… --- p.26
Chapter 2.4.1 --- Wavelength detune of light sources --- p.27
Chapter 2.4.2 --- Detune of the DI frequency response --- p.29
Chapter 2.4.3 --- Dispersion tolerance --- p.30
Chapter 2.5 --- Summary --- p.32
Chapter 3 --- INTENSITY-MODULATED LABELLING ON OPTICAL FSK OR DPSK PAYLOADS IN OLS NETWORKS --- p.34
Chapter 3.1 --- Existing Labelling Schemes and Their Features --- p.34
Chapter 3.1.1 --- Bit serial labelling --- p.35
Chapter 3.1.2 --- Subcarrier multiplexed (SCM) labelling --- p.36
Chapter 3.1.3 --- Orthogonally modulated labelling --- p.37
Chapter 3.2 --- The Proposed 00K Labelling Scheme and OLS System Architecture --- p.38
Chapter 3.3 --- All-Optical Label Swapping and Other Critical Issues --- p.39
Chapter 3.4 --- System demonstration --- p.40
Chapter 3.5 --- Summary --- p.45
Chapter 4 --- PERFORMANCE CHARACTERIZATION OF THE ASK/FSK AND ASK/DPSK ORTHOGONAL SIGNALS --- p.46
Chapter 4.1 --- Introduction and Formulation --- p.46
Chapter 4.2 --- Theoretical Analysis --- p.48
Chapter 4.2.1 --- Optical ASK performance in orthogonal signals --- p.48
Chapter 4.2.2 --- Optical FSK performance in ASK/FSK signals --- p.49
Chapter 4.2.3 --- Optical DPSK performance in ASK/DPSK signals --- p.51
Chapter 4.3 --- Analytical and Experimental Results --- p.55
Chapter 4.4 --- Conclusion --- p.57
Chapter 5 --- SUMMARY --- p.58
Chapter 5.1 --- Thesis Summary --- p.58
Chapter 5.2 --- Future Work --- p.59
LIST OF PUBLICATIONS --- p.61
REFERENCES --- p.62
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Wu, Tsung-Lin, and 吳宗霖. "Digital Signal Processing of Multiband Frequency Modulation Continuous Wave Active Electronic Scanning Array Radar." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/4q567u.
Full textAbstract:
碩士國立中興大學
電機工程學系所
106
In recent years, the measurement of distance and orientation of objects gradually draws people’s attentions. Radar will not be affected by weather or light, thereby influencing the accuracy. Therefore, radar is often used in our daily lives. The frequency modulated continuous wave (FMCW) radar can measure distances but it usually can’t obtain the directions of objects. Therefore, we utilized the concept of array antennas and single-band modulation technique to make it possible to detect multiple directions simultaneously. In this thesis, eight antennas are aligned as a 1-D antenna array, so that the radar system can detect three directions at the same time. The beamforming technology is also applied to both the transmitter (Tx) and the receiver (Rx) to make the power of radar beams narrowed to the direction to be observed. The simulation results show the power to the objects to be observed is increased by about 20 dB, and the power to the objects in the other directions is suppressed by about 20 dB. In addition, the radio-frequency (RF) VCO providing the two orthogonal signals of the single sideband modulation induces the issues of IQ imbalance. However, in the conventional fixed RF-frequency communication systems, the correction of this effect is only applied to the receiver. In this radar system, it is necessary to correct this non-ideal effect at the transmitter in this radar architecture, because the original single sideband signals will become double sideband signals after modulation without correction. That will be almost impossible to identify the number of objects. Therefore, this paper refers to a document with corrections on both the transmitting end and the receiving end. Here, the correction processes are performed at the transmitter. The up-converted signals are fed back directly to the down conversion mixer to extract the quantity of IQ imbalance by considering the delay time of the feedback path. This calibration process can reduce the power of the imaging peaks at the receiver by 40 dB by simulation. For hardware implementation, this thesis proposes the hardware design to process the digital signals at the Tx and the Rx. The key functional blocks include Tx/Rx beamforming, IQ calibration and integration of the fast Fourier transform provided by Xilinx. Because of the 8 antennas, the hardware may be increased by 8 times. Fortunately, owing to the moderate speed requirement, the calculation units may be shared sometimes. Finally, the hardware of this digital calibration/correction process was implemented using Virtex7 XCVX330T of Xilinx for verification. The APR tool of ISE Design Suite 14.5 version was used with the synthesized clock rate of 193.9MHz and APR clock rate of 176.1 MHz.
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Rosales, Roberto. "Integrated silicon bipolar wideband frequency modulation circuits for high-performance analog lightwave transmission." Thesis, 2003. http://hdl.handle.net/2429/14894.
Full textAbstract:
This thesis describes the research done to achieve wideband frequency modulator and
demodulator circuits for transmission of analog multi-channel cable television (CATV). These circuits were fabricated in an advanced silicon bipolar technology and resulted in the best-reported
fully electronic implementation of a modulator for wideband frequency modulation
(WFM) of CATV signals. Design of the modulator is achieved by using an emitter-coupled multivibrator (ECM) based oscillator. The viability of this approach is based on the ECM wideband tuning linearity at high-speed operation, particular noise requirements of CATV
transmission, and a novel phase noise reduction technique. Results for an ECM-based current-controlled oscillator (ICO) show linear operation in
the range of 1GHz to 2.5GHz. Results for a linearized ECM-based voltage-controlled oscillator (VCO) show linear operation in the range of 1.5GHz to 2GHz. Linearity, from static tuning measurements, show maximum deviations from an ideal linear fit of 15MHz, and 1.5MHz for the ICO and VCO respectively. Results for a wideband delay-line demodulator show linear
operation in a range of 2.5GHz, with back-to-back modulator/demodulator modulation
bandwidth of 1GHz. A state-of-the art phase noise measurement system, based on automatic data gathering with a spectrum analyzer followed by mathematical post-processing, is presented. This system measures the phase noise of a variable oscillator versus tuning input, at a fixed offset from the
carrier, with better accuracy than the best dedicated commercial measurement instrument
available at the time. The first study of phase noise in high-speed ECMs is presented from experimental measurements and circuit noise simulations. This study revealed new findings on the fundamental noise limits of ECMs. It was found that, at high frequencies, shot noise of the ECM core transistors dominates oscillator phase noise. Furthermore, phase noise was found to
be directly proportional to the ECM tail current and inversely proportional to the square of ECM timing capacitor. This lead to a simple and novel optimization design approach to reduce phase noise by scaling up, by the same factor, the tail current and timing capacitor with minimal effects on tuning linearity. In addition, the modulator perspectives in a narrowcast WFM system are explored through system calculations.
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張桄瑋. "Application of High Frequency Pulse Width Modulation Inverter to Contactless Power Transmission System." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/41830471878174685459.
Full textAbstract:
碩士國立彰化師範大學
電機工程學系
98
With the advances in the power electronics technology, the traditional power transmission is no longer limited to the contact method; contactless power transmission can be another choice. Contactless power transmission is similar to a transformer, and air gap or magnetic flux leakage is a factor to power transmission quality. Thus, increasing the current efficiency leads to better transmission efficiency. This research has constructed a high-frequency 20kHz full-bridge inverter, and the input pulse signal was generated by using a microprocessor; multiple stage circuits are used in order to generate a 20kHz high frequency sinusoidal wave output. The high-frequency sinusoidal wave can therefore transmitted to the load by contactless method, and the method is based on electromagnetic coupling. Keywords: Inverter, High-frequency sinusoidal, Power transmission
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Li, Yu-chen, and 李昱蓁. "Coherent and Noncoherent Space-Time Modulation for Single-Carrier Block Transmission over Frequency-Selective Channels." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/20556569555351308304.
Full textAbstract:
碩士國立臺灣科技大學
電機工程系
97
This dissertation includes two parts. The first part deals with time-reversal single carrier orthogonal space-time blocked technique employed in a multi-access CDMA uplink system over a quasi-static frequency selective fading channel. To avert the rate loss problem normally encounter in convolutionally coded space-time block modulation, we assign each user multiple spreading sequences so as to expand constellation size of orthogonal space-time codes. At receiver,one approaches, namely single-user detectors based on minimum mean-square error (MMSE) sense. Indeed, in computer simulations this receivers in terms of bit error rate (BER) indicates that the computational complexity was traded for performance gain. We, rather than assume channel state information (CSI) known to both transmitter and receiver, consider noncoherent space-time modulation in single-carrier block system over quasi-static frequency-selective fading channel. Indeed, capitalizing on multi-channel input-output relation in time domain, we construct space-time codes of constant signaling amplitude by means of complex orthogonal sequences to achieve maximal diversity gain along with coding advantage. Numerical result indicates that SC block system can outperform the orthogonal frequency division multiplexing (OFDM) counterpart, which additionally suffers from higher peak-to-average power ratio (PAPR), in terms of block error rate (BLER) under the same scenario conducted in simulations
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Chen, Guan-Hao, and 陳冠豪. "Orthogonal frequency division multiplexing using continuous phase modulation with time-limited and time-unlimited phase shaping pulses." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/57891816003298554741.
Full textAbstract:
碩士國立高雄第一科技大學
電腦與通訊工程研究所
102
Orthogonal Frequency Division Multiplexing (OFDM) modulation have the properties of high rates of data transmission capability, spectral performance improvement and robust to multi-path fading, inter-symbol interference, co-channel interference, now it is applied broadly to a wireless communication system. Continuous Phase Modulation (CPM) signals have the properties of constant envelope, bandwidth efficiency, power efficiency and low spectral side-lobe. However, most of the CPM modulation populations can not produce orthogonal subchannel signals, it can not be used in OFDM systems, in this paper, and we derive what groups CPM modulation applied to OFDM systems, the results show that by appropriate selection of the frequency of the modulation factor and the difference between the sub-channels, and the two pulse shaping phase of CPM: Rectangular Time-Unlimited Phase Shaping Pulses (REC-TU) and Rectangular Time-limited Phase Shaping Pulses (REC-TL), OFDM signals orthogonal to meet with overlapping spectral characteristics, we derive a system for white noise and Flat Rayleigh Fading Channels BER simulation and analysis, the results showed that meet coefficient OFDM-CPM modulation system is a so-called most Catastrophic Modulation Index characteristics, so the error rate than the Euclidean distance estimation is better, results with BPSK BER do performance and analyzed and compared. In our research, OFDM-CPM-TL in the multi-carrier transmission for each subcarrier frequency spacing should be less than OFDM-CPM-TU, which may indicate OFDM-CPM-TL spectrum efficiency can be effectively utilized for high-rate data transmission. In addition, this study did not explore how to use OFDM in the Fast Fourier Transformation (FFT) and Inverse Fast Fourier Transformation (IFFT) mechanism to simplify the design of the transmitter and the receiver, this is the future needs to be done.
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Sheng-JieWu and 吳勝傑. "Asymmetric Multiple Inductive Coupling Coil for Wireless Power Transmission System with Self-Frequency Modulation Efficiency Tracking." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/98784635647963472653.
Full textAbstract:
碩士國立成功大學
電機工程學系碩士在職專班
104
This study aims to analyze the frequency response and efficiency improvement design of three-coil asymmetric multiple inductive coupling coil structure for wireless power transmission. In consideration of current wireless power transmission coil structure requiring correct alignment for the optimal power transmission efficiency, an extra relay compensation coil is added to enhance the power transmission efficiency under power transmission coil dislocation so as to improve the efficiency reduction caused by coil displacement. Furthermore, since a secondary receiving coil is generally installed on the chassis of an electric vehicle, where the area is limited, a repeating coil is therefore added at the primary feeder coil end and is flush with the feeder coil. The repeating coil design process is proposed by analyzing the equivalent model derived formula of asymmetric coil compensation structure. The efficiency promotion method proposed in this study is then tested by analyzing the circuit model of multiple coupling coil structure. Under SAE J2954 inductive charging standards, the best compensation capacitor design process is calculated when the frequency separation appears on 81.38 kHz~90 kHz to achieve the optimal transmission efficiency by regulating the system operation frequency. The experimental result reveals that the displacement reduces the system transmission efficiency down to 80 % and the deviation distance respectively enhances 26.3 % and 16.7 % in the lateral and vertical deviation experiment. In regard to the self-regulated frequency, the efficiency could maintain 93 % by regulating the system operation frequency when the secondary compensation capacitor deviates ±1 %.
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Chiu, Shang-Chuan, and 邱上權. "The Microstrip Antenna for 76~81 GHz Frequency Modulation Continuous Wave Automotive Multiple-Input Multiple-Output Array Radar." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/vv9344.
Full textAbstract:
碩士國立交通大學
電信工程研究所
107
In this thesis, we design a planar printed microstrip antenna operating in frequency band of 76GHz to 81GHz for frequency modulated continuous wave (FMCW) multiple-input multiple-output (MIMO) array radar. The goal of this thesis is to design a radiation pattern with a narrow beam in the vertical plane, a wide beam in the horizontal plane and being stable in 76GHz to 81GHz, which keeps the back-end FMCW radar system to calculate distances and angles precisely. The antenna array is composed of 4 rows of antenna sub-arrays, and each row of sub-arrays is composed of eight series fed patch antenna. Finally, the measurement results of the antenna, the main beam of E plane about 〖10〗^° and the main beam of H plane about 〖80〗^°.
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洪璟榮. "Design and implementation of video frequency modulation and data hybris signal Transmission of short bus integrated service local area network." Thesis, 1986. http://ndltd.ncl.edu.tw/handle/07199181267319708868.
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"Transmission Strategies for Two-Way Relay Channels." Doctoral diss., 2015. http://hdl.handle.net/2286/R.I.36464.
Full textAbstract:
abstract: The recent proposal of two-way relaying has attracted much attention due to its promising features for many practical scenarios. Hereby, two users communicate simultaneously in both directions to exchange their messages with the help of a relay node. This doctoral study investigates various aspects of two-way relaying. Specifically, the issue of asynchronism, lack of channel knowledge, transmission of correlated sources and multi-way relaying techniques involving multiple users are explored.
With the motivation of developing enabling techniques for two-way relay (TWR) channels experiencing excessive synchronization errors, two conceptually-different schemes are proposed to accommodate any relative misalignment between the signals received at any node. By designing a practical transmission/detection mechanism based on orthogonal frequency division multiplexing (OFDM), the proposed schemes perform significantly better than existing competing solutions. In a related direction, differential modulation is implemented for asynchronous TWR systems that lack the channel state information (CSI) knowledge. The challenge in this problem compared to the conventional point-to-point counterpart arises not only from the asynchrony but also from the existence of an interfering signal. Extensive numerical examples, supported by analytical work, are given to demonstrate the advantages of the proposed schemes.
Other important issues considered in this dissertation are related to the extension of the two-way relaying scheme to the multiple-user case, known as the multi-way relaying. First, a distributed source coding solution based on Slepian-Wolf coding is proposed to compress correlated messages close to the information theoretical limits in the context of multi-way relay (MWR) channels. Specifically, the syndrome approach based on low-density parity-check (LDPC) codes is implemented. A number of relaying strategies are considered for this problem offering a tradeoff between performance and complexity. The proposed solutions have shown significant improvements compared to the existing ones in terms of the achievable compression rates. On a different front, a novel approach to channel coding is proposed for the MWR channel based on the implementation of nested codes in a distributed manner. This approach ensures that each node decodes the messages of the other users without requiring complex operations at the relay, and at the same time, providing substantial benefits compared to the traditional routing solution.Dissertation/Thesis
Doctoral Dissertation Electrical Engineering 2015
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Gururaja, Srinivas. "Joint optimal pilot placement and power allocation with space frequency code design and adaptive modulation for video transmission over MIMO-OFDM systems." 2007. http://proquest.umi.com/pqdweb?did=1417814041&sid=8&Fmt=2&clientId=39334&RQT=309&VName=PQD.
Full textAbstract:
Thesis (M.S.)--State University of New York at Buffalo, 2007.Title from PDF title page (viewed on Feb. 19, 2008) Available through UMI ProQuest Digital Dissertations. Thesis adviser: Liu, Pao-Lo. Includes bibliographical references.
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Lin, Yi-Fan, and 林以凡. "Antenna Distance Analysis and Design for Wider Angle Detection for Mono-pulse Continuous Wave Doppler Radar and Characterization of High Frequency Transmission Line On Flexible Substrate." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/28046973032985397508.
Full textAbstract:
碩士國立臺灣大學
電信工程學研究所
102
Two antenna layouts are realized in two different kinds of fabrication process which are LTCC (low temperature co-fired ceramics) and PCB (printed circuit board) in a limited area for monopulse radar system that includes one transceiving and two receiving antennas. The radar system uses Doppler effect to determine the speed of the target and the monopulse ratio which is determined by radiation modes of sum and difference pattern to detect the angle of the target. Due to limited area, two receiving antennas are forced to place in the distance smaller than a wavelength, the isolation between two receiving antennas becomes a big issue that we can’t be ignored. I obstruct the radiated pattern away from the broadside direction. So we use the antenna theory to reconsider the signal we may receive in order to have a reliable measurement. The operating mechanism and details of the antenna design are discussed. Experimental and simulated results are both presented and discussed. The 3rd and 4th Chapter will discuss the characteristic of the transmission lines fabricated on flexible substrate, because of the difficulty and price issue, multilayer substrate is not comparable with single layer substrate. Take the advantage of the flexibility of the transmission line, we can connect substrate with it to accomplish a new 3D package. In this part, we will first introduce the fabrication process, how to produce these materials and their parameters. Then the second part is the introduction of the measurement. TRL calibration method is used to remove the error caused by equipment we used in measurement. At 4th chapter, it will show scattering parameters. By the measurement results we can get permittivity and loss tangent. Comparison between measurement and simulation will also be presented. The last chapter is the conclusion of this thesis and the future work.
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"Error control coded data transmision over FM supplementary signal transmission radio channels." Thesis, 2015. http://hdl.handle.net/10210/14748.
Full textAbstract:
M.Ing. (Electrical and Electronic Engineering)With all the talk about the Information Highway and its construction, there is also a channel which is highly underestimated and thus almost ignored. On normal FM radio transmissions extra bandwidth exists, suitable for the transmission of audio and data. In this thesis the effects of interference on data transmission over the Supplementary Signal Transmission (SST) channel are analysed. The channel is characterized in terms of the Bit Error Rate (BER) versus field strength and distance from a transmitter ...
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Bhat, Ritesh Ashok. "Efficient, High power Precision RF and mmWave Digital Transmitter Architectures." Thesis, 2018. https://doi.org/10.7916/D8Z620XN.
Full textAbstract:
Digital transmitters offer several advantages over conventional analog transmitters such as reconfigurability, elimination of scaling-unfriendly, power hungry and bulky analog blocks and portability across technology. The rapid advancement of technology in CMOS processes also enables integration of complex digital signal processing circuitry on the same die as the digital transmitter to compensate for their non-idealities. The use of this digital assistance can, for instance, enable the use of highly efficient but nonlinear switching-class power amplifiers by compensating for their severe nonlinearity through digital predistortion. While this shift to digitally intensive transmitter architectures is propelled by the benefits stated above, several pressing challenges arise that vary in their nature depending on the frequency of operation - from RF to mmWave.
Millimeter wave CMOS power amplifiers have traditionally been limited in output power due to the low breakdown voltage of scaled CMOS technologies and poor quality of on-chip passives. Moreover, high data-rates and efficient spectrum utilization demand highly linear power amplifiers with high efficiency under back-off. However, linearity and high efficiency are traditionally at odds with each other in conventional power amplifier design. In this dissertation, digital assistance is used to relax this trade-off and enable the use of state-of-the-art switching class power amplifiers. A novel digital transmitter architecture which simultaneously employs aggressive device-stacking and large-scale power combining for watt-class output power, dynamic load modulation for linearization, and improved efficiency under back-off by supply-switching and load modulation is presented.
At RF frequencies, while the problem of watt-class power amplification has been long solved, more pressing challenges arise from the crowded spectrum in this regime. A major drawback of digital transmitters is the absence of a reconstruction filter after digital-to-analog conversion which causes the baseband quantization noise to get upconverted to RF and amplified at the output of the transmitter. In high power transmitters, this upconverted noise can be so strong as to prevent their use in FDD systems due to receiver desensitization or impose stringent coexistence challenges. In this dissertation, new quantization noise suppression techniques are presented which, for the first time, contribute toward making watt-class fully-integrated digital RF transmitters a viable alternative for FDD and coexistence scenarios. Specifically, the techniques involve embedding a mixed-domain multi-tap FIR filter within highly-efficient watt-class switching power amplifiers to suppress quantization noise, enhancing the bandwidth of noise suppression, enabling tunable location of suppression and overcoming the limitations of purely digital-domain filtering techniques for quantization noise.
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"Secure mobile radio communication over narrowband RF channel." Chinese University of Hong Kong, 1992. http://library.cuhk.edu.hk/record=b5887043.
Full textAbstract:
by Wong Chun Kau, Jolly.Thesis (M.Phil.)--Chinese University of Hong Kong, 1992.
Includes bibliographical references (leaves 84-88).
ABSTRACT --- p.1
ACKNOWLEDGEMENT --- p.3
Chapter 1. --- INTRODUCTION --- p.7
Chapter 1.1 --- Land Mobile Radio (LMR) Communications
Chapter 1.2 --- Paramilitary Communications Security
Chapter 1.3 --- Voice Scrambling Methods
Chapter 1.4 --- Digital Voice Encryption
Chapter 1.5 --- Digital Secure LMR
Chapter 2. --- DESIGN GOALS --- p.20
Chapter 2.1 --- System Concept and Configuration
Chapter 2.2 --- Operational Requirements
Chapter 2.2.1 --- Operating conditions
Chapter 2.2.2 --- Intelligibility and speech quality
Chapter 2.2.3 --- Field coverage and transmission delay
Chapter 2.2.4 --- Reliability and maintenance
Chapter 2.3 --- Functional Requirements
Chapter 2.3.1 --- Major system features
Chapter 2.3.2 --- Cryptographic features
Chapter 2.3.3 --- Phone patch facility
Chapter 2.3.4 --- Mobile data capability
Chapter 2.4 --- Bandwidth Requirements
Chapter 2.5 --- Bit Error Rate Requirements
Chapter 3. --- VOICE CODERS --- p.38
Chapter 3.1 --- Digital Speech Coding Methods
Chapter 3.1.1 --- Waveform coding
Chapter 3.1.2 --- Linear predictive coding
Chapter 3.1.3 --- Sub-band coding
Chapter 3.1.4 --- Vocoders
Chapter 3.2 --- Performance Evaluation
Chapter 4. --- CRYPTOGRAPHIC CONCERNS --- p.52
Chapter 4.1 --- Basic Concepts and Cryptoanalysis
Chapter 4.2 --- Digital Encryption Techniques
Chapter 4.3 --- Crypto Synchronization
Chapter 4.3.1 --- Auto synchronization
Chapter 4.3.2 --- Initial synchronization
Chapter 4.3.3 --- Continuous synchronization
Chapter 4.3.4 --- Hybrid synchronization
Chapter 5. --- DIGITAL MODULATION --- p.63
Chapter 5.1 --- Narrowband Channel Requirements
Chapter 5.2 --- Narrowband Digital FM
Chapter 5.3 --- Performance Evaluation
Chapter 6. --- SYSTEM IMPLEMENTATION --- p.71
Chapter 6.1 --- Potential EMC Problems
Chapter 6.2 --- Frequency Planning
Chapter 6.3 --- Key Management
Chapter 6.4 --- Potential Electromagnetic Compatibility (EMC) Problems
Chapter 7. --- CONCLUSION --- p.80
LIST OF ILLUSTRATIONS --- p.81
REFERENCES --- p.82
APPENDICES --- p.89
Chapter I. --- Path Propagation Loss(L) Vs Distance (d)
Chapter II. --- Speech Quality Assessment Tests performed
by Special Duties Unit (SDU)
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Jarvis, Thomas William. "Novel tools for ultrafast spectroscopy." Thesis, 2011. http://hdl.handle.net/2152/ETD-UT-2011-12-4456.
Full textAbstract:
Exciton dynamics in semiconductor nanostructures are dominated by the effects of many-body physics. The application of coherent spectroscopic tools, such as two-dimensional Fourier transform spectroscopy (2dFTS), to the study of these systems can reveal signatures of these effects, and in combination with sophisticated theoretical modeling, can lead to more complete understanding of the behaviour of these systems.
2dFTS has previously been applied to the study of GaAs quantum well samples. In this thesis, we outline a precis of the technique before describing our own experiments using 2dFTS in a partially collinear geometry. This geometry has previously been used to study chemical systems, but we believe these experiments to be the first such performed on semiconductor samples. We extend this technique to a reflection mode 2dFTS experiment, which we believe to be the first such measurement.
In order to extend the techniques of coherent spectroscopy to structured systems, we construct an experimental apparatus that permits us to control the beam geometry used to perform four-wave mixing reflection measurements. To isolate extremely weak signals from intense background fields, we extend a conventional lock-in detection scheme to one that treats the optical fields exciting the sample on an unequal footing. To the best of our knowledge, these measurements represent a novel spectroscopic tool that has not previously been described.text