Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 27 for “"nonlinear distortion"”.
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Compensation of nonlinear distortion in RF amplifiers for mobile communications
Compensation of nonlinear distortion of power amplifiers in mobile communications is an important requirement for improving power consumption performance while maintaining efficiency, since mobile phone became an essential accessory for everyone nowadays. This problem demands a good power amplifier …
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Compensation of nonlinear distortion and frequency offset in OFDM systems
… scheme to wireless systems: sensitivities to nonlinear distortion and frequency offset. This dissertation deals with applications of compensation schemes in OFDM systems to solve the sensitivity problems associated with nonlinear distortion and frequency offset in the systems. With regard to …
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Compensation technique for nonlinear distortion in RF circuits for multi-standard wireless systems
… This thesis introduces the existing problem in nonlinear components in a multi-standard wireless system due to interfering signals and suggests potential solution to the problem. Advances in RF and wireless systems with emerging new communication standards have made reconfigurablility and …
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Pre-compensation of nonlinear distortion of a silicon microring modulator in short reach systems
… system. One issue with Si-MRMs is the nonlinear electrical-to-optical modulation dynamics. This work investigates pre-compensation of this nonlinear distortion by back-calculation. An MRM model is firstly set up using Matlab. Through back-calculation of the model, an electrical drive …
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Dynamic range of analog fiber optic links used in microcellular mobile radio applications
… however presents some unique problems due to the nonlinearities of the fiber optics system and the noise introduced by it. In this thesis, we analyse the dynamic range of the fiber links used for these applications. The dynamic range is limited by the noise and the nonlinear distortion introduced …
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Design and implementation of adaptive baseband predistorter for OFDM nonlinear transmitter. Simulation and measurement of OFDM transmitter in presence of RF high power amplifier nonlinear distortion and the development of adaptive digital predistorters based on Hammerstein approach.
… design and measurement of a digital predistortion linearizer that is able to compensate the dynamic nonlinear distortion of a High Power Amplifier (PA). The effectiveness of the proposed baseband predistorter (PD) on the performance of a WLAN OFDM transmitter utilizing a nonlinear PA …
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Practical performance and system capacity of lightwave AM SCM video systems
… to large carrier-to-noise ratio (CNR) and low nonlinear distortion requirements. This research dissertation contains a comprehensive study of the system capacity of such systems based on theoretical analysis, experiment, and simulation. The practical performance of lightwave AM SCM systems are …
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Design and Linearization of Energy Efficiency Power Amplifier in Nonlinear OFDM Transmitter for LTE-5G Applications. Simulation and measurements of energy efficiency power amplifier in the presence of nonlinear OFDM transmitter system and digital predistortion based on Hammerstein-Wiener method
… evolution (OFDM-LTE) transmitter by reducing the nonlinear distortion of the RFPA. The first part of this work explores the design and implementation of 15.5 W class AB RF power amplifier, adopting a balanced technique to stimulate efficiency enhancement and redeeming exhibition of excessive power …
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Integrated Filters and Couplers for Next Generation Wireless Tranceivers
… of this thesis is to investigate the critical nonlinear distortion issues affecting RF/Microwave components such as power amplifiers (PA) and develop new and improved solutions that will improve efficiency and linearity of next generation RF/Microwave mobile wireless communication systems. This …
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New Techniques for Multicarrier Communication Systems
… which can lead to low power efficiency and nonlinear distortion at the transmit power amplifier. Tone reservation uses unavailable or reserved tones to design a peak-cancelling signal that lowers the PAR of a transmit OFDM block. Active-set methods provide a fast-converging PAR reduction …
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Toward More Intelligible Simultaneous Multi-channel Speech Enhancement and Recognition
… speech signal. The methods suffer from nonlinear distortion brought by the algorithm, which hurts the intelligibility of the speech and also downstream tasks such as automatic speech recognition (ASR). We propose a method that leverages multi-channel input that robustly reduces the …
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Interpreting otoacoustic emissions in humans : evidence for multiple generating mechanisms
… by two fundamentally different mechanisms: 1) nonlinear distortion induced by cochlear traveling: waves and 2) linear reflection 6f those waves from pre-existing micromechanical impedance perturbations. The model predicts that OAEs generated by wave-induced perturbations manifest a phase that …
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Evaluation performance of OFDM system using the selected mapping technique for WIMAX technology
… to handle very strong echoes and very less nonlinear distortion are the properties of the OFDM. One major disadvantage of OFDM is that the time domain OFDM signal which is the sum of several sinusoids leading to high peak to average power ratio (PAPR). This work, a technique is proposed in …
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ΜΕΛΕΤΗ ΚΑΙ ΥΠΟΛΟΓΙΣΜΟΣ ΤΗΣ ΕΠΙΘΥΜΗΤΗΣ ΠΡΟΠΑΡΑΜΟΡΦΩΣΗΣ ΓΙΑ ΤΗΝ ΔΙΟΡΘΩΣΗ ΤΗΣ ΕΙΣΑΓΟΜΕΝΗΣ ΠΑΡΑΜΟΡΦΩΣΗΣ ΣΕ ΜΗ ΓΡΑΜΜΙΚΟΥΣ ΠΟΛΥΕΠΙΠΕΔΟΥΣ ΨΗΦΙ...
… THE CONTRAST THEY ARE ESPECIALLY SUSPECTIBILETO NONLINEAR DISTORTION. AS IS KNOWN, TWT AMPLIFIERS, USED IN A SATELLITE TRANSPONDER OR A TERRESTRIAL REPEATER, ARE USUALLY WORKING NEAR SATURATION BECAUSE OF HIGH SYSTEM GAIN REQUIREMENTS [3,4]. IN THIS MODE OF OPERATION THE AMPLIFIEREXHIBITS AM/AM …
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Bayes meets Bach: applications of Bayesian statistics to audio restoration
Memoryless nonlinear distortion can be present in audio signals, from recording to reproduction: bad quality or amateurishly operated equipments, physically degraded media and low quality reproducing devices are some examples where nonlinearities can naturally appear. Another quite common defect in …
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Phased array impedance tuning, secure transmission, and nonlinear spatial intermodulation suppression for next-generation radar and communications systems.
… beams are transmitted as a result of the nonlinearities in these power amplifiers and can degrade both radar and communications mission abilities. The research presented in this dissertation resolves the nonlinear intermodulation products caused by these power amplifier nonlinearities by …
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Optimal nonlinear digital signal processing : a dynamical systems approach
This thesis addresses optimal nonlinear digital signal processing problems aimed to improve power efficiency of modern wireless transmission systems. The first part of this thesis is motivated by peak-to-average power ratio reduction of communication signals. The problem is formulated as …
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Predistortion for Nonlinear Power Amplifiers with Memory
… that are used today. In order to reduce distortion while maintaining high power conversion efficiency in a power amplifier, linearization schemes are needed. In addition, significant frequency-dependent Memory Effects result in high power amplifiers operating on wideband signals. …
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Numerical investigation of air vehicle noise propagation effects
… far-field study of this thesis focuses on the nonlinear propagation of helicopter rotor noise using the Burgers equation, a well known one direction propagation method. The Burgers equation incorporates geometrical spreading, atmospheric absorption and nonlinear distortion effects. Towards this …
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Characterization of the Dynamics of Optically-Injected Nanostructure Lasers
… of the resonance frequency, suppressing nonlinear distortion, and reducing relative intensity noise, mode-hopping, and chirp. The nonlinear dynamics associated with optically-injected semiconductor lasers has also attracted great interest due to potential applications including: …
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