Non Co-Operative Detection of LPI/LPD Signals Via Cyclic Spectral Analysis

This research proposes and evaluates a novel technique for detecting LPI/LPD communication signals using a digital receiver primarily designed to detect radar signals, such as a Radar Warning Receiver (RWR) or an Electronic Support Measures (ESM) receiver. The proposed Cyclic Spectrum Analysis (CSA) receiver is a robust detector that takes advantage of the spectral correlation properties of second-order cyclostationary signals. A computationally efficient algorithm is used to estimate the Spectral Correlation Function (SCF). Using state-of-the-art FFT processing, it is expected that the proposed CSA receiver architecture could estimate the entire cyclic spectrum m approximately 0.6 ms. The estimate is then reduced to an energy related test statistic that is valid for all cycle frequencies within the receiver bandwidth. By producing an estimate of the cyclic spectrum, the CSA receiver also benefits post-detection tasks such as signal classification and exploitation. As modeled, the ideal CSA receiver detection performance is within 1.0 dB of the radiometer in benign signal environments and consistently outperforms the radiometer in adverse signal environments. The effect on detection performance when the CSA receiver is implemented with channelized and quadrature digital receiver architectures is also examined

Data transmission oriented on the object, communication media, application, and state of communication systems tactical communication system application

A proposed communication system architecture is denoted TOMAS, which stands for data Transmission oriented on the Object, communication Media, Application, and state of communication Systems. Given particular tactical communication system scenarios of image transmission over a wireless LOS (Line-of-Sight) channel, a wireless TOMAS system demonstrates superior performance compared to the conventional system, which is a combination of JPEG2000 image compression and OFDM transmission, in restored image quality parameters over a wide range of wireless channel parameters. The wireless TOMAS system provides progressive lossless image transmission under the influence of moderate fading without any kind of channel coding and estimation. The TOMAS system employs a fast proprietary patent pending algorithm Sabelkin (2011), which does not employ any multiplications, and it uses three times less real additions than the algorithm of JPEG2000+OFDM. The TOMAS system exploits a specialized wavelet transform combined for image coding and channel modulation

Wavelet-based multi-carrier code division multiple access systems

EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Adaptive Illumination Patterns for Radar Applications

The fundamental goal of Fully Adaptive Radar (FAR) involves full exploitation of the joint, synergistic adaptivity of the radar\u27s transmitter and receiver. Little work has been done to exploit the joint space time Degrees-of-Freedom (DOF) available via an Active Electronically Steered Array (AESA) during the radar\u27s transmit illumination cycle. This research introduces Adaptive Illumination Patterns (AIP) as a means for exploiting this previously untapped transmit DOF. This research investigates ways to mitigate clutter interference effects by adapting the illumination pattern on transmit. Two types of illumination pattern adaptivity were explored, termed Space Time Illumination Patterns (STIP) and Scene Adaptive Illumination Patterns (SAIP). Using clairvoyant knowledge, STIP demonstrates the ability to remove sidelobe clutter at user specified Doppler frequencies, resulting in optimum receiver performance using a non-adaptive receive processor. Using available database knowledge, SAIP demonstrated the ability to reduce training data heterogeneity in dense target environments, thereby greatly improving the minimum discernable velocity achieved through STAP processing

Circularly Polarized Antennas for GNSS Applications

Global navigation satellite system (GNSS) is developing rapidly. Modern GNSS technology is facing challenges for researchers to explore. One hot topic is the multi-system GNSS device. The motivation for the antenna designers is to miniaturize the size of the antenna and meanwhile keep its standard performance. It is a challenging task for an antenna array design to achieve a wide bandwidth, high gain, small size, good coverage, and simple fabrication technique all at the same time. This thesis develops several different novel compacts, high gain, and wide bandwidth circularly polarized (CP) antenna capable of providing wide coverage for GNSS frequency bands from 1.16 GHz to 1.6 GHz to cover the GPS L1-L5 bands, GLONASS G1, G2 and G3 as well as the Galileo E5a, E5b, E6, and E1bands

Integration of plastids in the plant calcium signalling network in response to environmental stimuli.

Transient elevations in intracellular free Ca2+ concentration are known to mediate plant responses to a wide variety of abiotic and biotic stimuli. To elucidate the contribution of plastids to Ca2+ homeostasis and signalling in the plant cell, we generated Arabidopsis thaliana lines stably expressing the bioluminescent Ca2+ reporter aequorin targeted to different chloroplast subcompartments, i.e. the outer envelope, the stroma, the thylakoid membrane and the thylakoid lumen. Ca2+ measurements in response to environmental stimuli were carried out in entire seedlings, as well as in cell suspension cultures, obtained from in vitro dedifferentiation of Arabidopsis explants. Monitoring of Ca2+ dynamics allowed to dissect stimulus-specific Ca2+ signals in amyloplasts and chloroplasts, as well as the occurrence of dark-induced intraplastidial Ca2+ fluxes, characterized by unique kinetic parameters. To get insights into the homeostatic mechanisms allowing for chloroplast Ca2+ fluxes, a mutant line lacking a putative plastidial Ca2+-permeable transporter was transformed with the construct encoding the stroma-targeted aequorin chimera. The obtained results shed new light on the complex network underlying the Ca2+-mediated transduction of environmental stimuli in plants at an intracellular level. This complex kit of chloroplast-targeted aequorin probes turned out to be a valuable tool for the monitoring of organellar Ca2+ dynamics during signal transduction. In the last part of the work the ability of Chlamydomonas reinhardtii, a unicellular freshwater/soil green alga, to evoke intracellular Ca2+ changes ([Ca2+]) in response to different environmental stimuli was considered. As there is no evidence in the literature about environmental stimuli that trigger cytosolic [Ca2+] variations in Chlamydomonas, the first step had necessarily to deal with the identification of environmental cues evoking cytosolic [Ca2+] elevations in the microalga. Chlamydomonas cells, loaded with the Ca2+-responsive fluorescent dye Oregon Green-BAPTA, were challenged with stimuli previously used in this work on Arabidopsis. Moreover, the alga was also challenged with a hypoosmotic shock, that resulted to trigger cytosolic [Ca2+] elevations, and the nature of the observed dynamics was investigated. Taken together, the obtained results indicate that some aspects of Ca2+ signalling do not appear to be conserved between the green alga Chlamydomonas and the higher plant Arabidopsis, but other elements in Ca2+-mediated responses to osmotic shocks are similar. These differences may be due to the different Ca2+ signalling toolkits found in plants and algae and/or to the different physiology of these model organisms, both belonging to the Viridiplantae clade. Investigation on the Ca2+ handling mechanisms operating in different photosynthetic organisms of phylogenetic interest may shed new light on the evolutionary history of the Ca2+ signalling toolkit

Abstracts on Radio Direction Finding (1899 - 1995)

The files on this record represent the various databases that originally composed the CD-ROM issue of "Abstracts on Radio Direction Finding" database, which is now part of the Dudley Knox Library's Abstracts and Selected Full Text Documents on Radio Direction Finding (1899 - 1995) Collection. (See Calhoun record https://calhoun.nps.edu/handle/10945/57364 for further information on this collection and the bibliography). Due to issues of technological obsolescence preventing current and future audiences from accessing the bibliography, DKL exported and converted into the three files on this record the various databases contained in the CD-ROM. The contents of these files are: 1) RDFA_CompleteBibliography_xls.zip [RDFA_CompleteBibliography.xls: Metadata for the complete bibliography, in Excel 97-2003 Workbook format; RDFA_Glossary.xls: Glossary of terms, in Excel 97-2003 Workbookformat; RDFA_Biographies.xls: Biographies of leading figures, in Excel 97-2003 Workbook format]; 2) RDFA_CompleteBibliography_csv.zip [RDFA_CompleteBibliography.TXT: Metadata for the complete bibliography, in CSV format; RDFA_Glossary.TXT: Glossary of terms, in CSV format; RDFA_Biographies.TXT: Biographies of leading figures, in CSV format]; 3) RDFA_CompleteBibliography.pdf: A human readable display of the bibliographic data, as a means of double-checking any possible deviations due to conversion

ATR-FTIR Spectroscopy-Linked Chemometrics:A Novel Approach to the Analysis and Control of the Invasive Species Japanese Knotweed

Japanese knotweed (Reynoutria japonica), an invasive plant species, causes negative environmental and socio-economic impacts. A female clone in the United Kingdom, its extensive rhizome system enables rapid vegetative spread. Plasticity permits this species to occupy a broad geographic range and survive harsh abiotic conditions. It is notoriously difficult to control with traditional management strategies, which include repetitive herbicide application and costly carbon-intensive rhizome excavation. This problem is complicated by crossbreeding with the closely related species, Giant knotweed (Reynoutria sachalinensis), to give the more vigorous hybrid, Bohemian knotweed (Fallopia x Bohemica) which produces viable seed. These species, hybrids, and backcrosses form a morphologically similar complex known as Japanese knotweed ‘sensu lato’ and are often misidentified. The research herein explores the opportunities offered by advances in the application of attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy-linked chemometrics within plant sciences, for the identification and control of knotweed, to enhance our understanding of knotweed biology, and the potential of this technique. ATR-FTIR spectral profiles of Japanese knotweed leaf material and xylem sap samples, which include important biological absorptions due to lipids, proteins, carbohydrates, and nucleic acids, were used to: identify plants from different growing regions highlighting the plasticity of this clonal species; differentiate between related species and hybrids; and predict key physiological characteristics such as hormone concentrations and root water potential. Technical advances were made for the application of ATR-FTIR spectroscopy to plant science, including definition of the environmental factors that exert the most significant influence on spectral profiles, evaluation of sample preparation techniques, and identification of key wavenumbers for prediction of hormone concentrations and abiotic stress. The presented results cement the position of concatenated mid-infrared spectroscopy and machine learning as a powerful approach for the study of plant biology, extending its reach beyond the field of crop science to demonstrate a potential for the discrimination between and control of invasive plant species