Electronic equipment, systems, and techniques: A compilation

Electronic circuits with specialized computer applications and control circuits are presented. Patent information is included

Energy Efficient Peak Power Reduction in OFDM with Amplitude Predistortion Aided by Orthogonal Pilots

The high Peak-to-Average Power Ratio (PAPR) is a main drawback of Orthogonal Frequency Division Multiplexing (OFDM) systems. We propose a two-step technique to reduce the PAPR consisting of a metric-based constellation extension method, such as Simple Amplitude Predistortion (SAP) algorithm, aided by Orthogonal Pilot Sequences (OPS) in a previous step, where we also provide a low-complex implementation of OPS scheme. We show that our proposal, named OP-SAP, outperforms previous approaches in terms of PAPR reduction, due to joining the benefits of Orthogonal Pilots with SAP algorithm. Moreover, it is energy efficient within two aspects: transmitted energy and implementation energy. OP-SAP saves up to 57% of transmitted energy per predistorted symbol compared to SAP. Regarding implementation energy, PAPR reduction techniques introduce some additional computational complexity, which requires extra cycles in the processor that demand energy consumption. We present an exhaustive analysis on computational power cost that shows the low power consumption of OP-SAP compared to other methods as SeLected Mapping (SLM), what yields a remarkable energy saving in its practical implementation.This work was supported in part by the Spanish National Projects GRE3N-SYST (TEC2011-29006-C03-03) and COMONSENS (CSD2008-00010), Fundación Carolina (Spain), and SENESCYT (Ecuador).Publicad

Pico- and femto-second optical pulse propagation in semiconductor optical amplifiers: analysis, optimization and quantum transmission line modelling

This thesis has theoretically and experimentally investigated the ultrashort optical pulse propagation in semiconductor optical amplifiers (SOAs), which is an important topic in the optical fiber communication and optical signal processing. Some new work has been done: Firstly, effects of carrier heating on the ultrashort optical pulse propagation in quantum well SOAs are first studied taking into account the holes’ non-parabolic density of states; for bulk SOAs, an accurate and simple analytical method to study carrier heating effects is presented based on Fermi-Dirac integrals approximation. Secondly, this thesis reports a novel bias current optimization method for ultrashort optical pulse distortionless amplification in SOAs based on the newly proposed bias current relation function. Detailed theoretical and experimental work is done to analyze the relation between the optimized bias current and the parameters of the input ultrashort pulse train. Finally, a novel modelling technique-quantum transmission line modelling (Q-TLM) method is proposed by combining quantum statistic description and photon-electron dynamic interaction process description. Q-TLM is used to establish models for quantum well and quantum dot structures and analyze the dynamic performance of ultrashort optical pulse propagation in SOAs. The Q-TLM technique provides an effective method to study semiconductor optical devices

SITE project. Phase 1: Continuous data bit-error-rate testing

The Systems Integration, Test, and Evaluation (SITE) Project at NASA LeRC encompasses a number of research and technology areas of satellite communications systems. Phase 1 of this project established a complete satellite link simulator system. The evaluation of proof-of-concept microwave devices, radiofrequency (RF) and bit-error-rate (BER) testing of hardware, testing of remote airlinks, and other tests were performed as part of this first testing phase. This final report covers the test results produced in phase 1 of the SITE Project. The data presented include 20-GHz high-power-amplifier testing, 30-GHz low-noise-receiver testing, amplitude equalization, transponder baseline testing, switch matrix tests, and continuous-wave and modulated interference tests. The report also presents the methods used to measure the RF and BER performance of the complete system. Correlations of the RF and BER data are summarized to note the effects of the RF responses on the BER

Development of advanced digital techniques for data acquisition processing and communication Interim scientific report

Design, video data characteristics, error control, and compression algorithms for Mars television mapping missio

Interferometric Synthetic Aperture Sonar Signal Processing for Autonomous Underwater Vehicles Operating Shallow Water

The goal of the research was to develop best practices for image signal processing method for InSAS systems for bathymetric height determination. Improvements over existing techniques comes from the fusion of Chirp-Scaling a phase preserving beamforming techniques to form a SAS image, an interferometric Vernier method to unwrap the phase; and confirming the direction of arrival with the MUltiple SIgnal Channel (MUSIC) estimation technique. The fusion of Chirp-Scaling, Vernier, and MUSIC lead to the stability in the bathymetric height measurement, and improvements in resolution. This method is computationally faster, and used less memory then existing techniques

Data transmission through channels pertubed by impulsive noise

Imperial Users onl