Control and evaluation of the ad-fmcomms5-ebz software-defined radio

Software-defined radios (SDR) have presented a new way to do telecommunication systems in a configurable, efficient and portable manner. With the rapid evolving capabilities of these systems, the traditional non-software-configurable ones are being left behind. This project explores the concept of software-defined radio in a theoretical and practical way using the ADFMComms5-EBZ, a SDR provided by Analog Devices with 4 transceivers. A complete analysis is done on the AD-FMComms5-EBZ, understanding all its physical components and its digital interface that make it software-configurable. Furthemore, its interaction with MATLAB/Simulink and with the IIO Oscilloscope application is studied, providing a profound explanation of the board's capabilities on these software. Finally, a few algorithms we found interesting are designed with MATLAB to enable all the potential of the board by reaching MIMO capabilities, analysing the phase of each transmitter and the reception order of symbols.Les ràdios definides per software (SDR) s'han presentat com a una nova manera de fer sistemes de telecomunicacions gràcies a la seva configurabilitat, eficiència i portabilitat. La seva evolució ha sigut ràpida i contínua, fent que els sistemes tradicionals que no son configurables en software s'hagin quedat enrere. Aquest projecte explora el concepte de ràdio definida per software de forma teòrica i pràctica utilitzant l'AD-FMComms5-EBZ, una SDR dissenyada per Analog Devices que incorpora 4 transceptors. En el projecte s'hi fa una anàlisi completa de l'AD-FMComms5-EBZ, entenent tots els seus components físics i la seva interfície digital que en permet la configurabilitat per via de software dels seus components. A més, s'estudia la seva interacció amb MATLAB/Simulink i amb l'aplicació IIO Oscilloscope, donant una explicació profusa de les capacitats de la placa amb aquest programari. Finalment, es dissenyen alguns algoritmes que hem trobat interessants amb MATLAB per a habilitar tot el potencial de la placa, aconseguint que funcioni com a un sistema MIMO, analitzant la fase ens els diferents transmissors i l'ordre de la recepció dels símbols.Las radios definidas por software (SDR) se han presentado como una nueva manera de hacer sistemas de telecomunicaciones gracias a su configurabilidad, eficiencia y portabilidad. Su evolución ha sido rápida y continua, haciendo que los sistemas tradicionales que no son configurables en software se hayan quedado atrás. Este proyecto explora el concepto de radio definida por software de forma teórica y práctica utilizando el AD-FMComms5-EBZ, una SDR diseñada por Analog Devices que incorpora 4 transceptores. En el proyecto se hace un análisis completo de la AD-FMComms5-EBZ, entendiendo todos sus componentes físicos y su interfaz digital que permite su configurabilidad por vía de software de sus componentes. Además, se estudia su interacción con MATLAB / Simulink y con la aplicación IIO Oscilloscope, dando una explicación profusa de las capacidades de la placa con este software. Finalmente, se diseñan algunos algoritmos que hemos encontrado interesantes con MATLAB para habilitar todo el potencial de la placa, consiguiendo que funcione como un sistema MIMO, analizando la fase en los diferentes transmisores y el orden de la recepción de los símbolos

Satellite Constellation Cost Modeling: An Aggregate Model

Satellite constellations and Distributed Spacecraft Mission (DSM) architectures offer unique benefits to Earth observation scientists and unique challenges to cost estimators. The Cost and Risk (CR) module of the Tradespace Analysis Tool for Constellations (TAT-C) being developed by NASA Goddard seeks to address some of these challenges by providing a new approach to cost modeling, which aggregates existing Cost Estimating Relationships (CER) from respected sources, cost estimating best practices, and data from existing and proposed satellite designs. Cost estimation through this tool is approached from two perspectives: parametric cost estimating relationships and analogous cost estimation techniques. The dual approach utilized within the TAT-C CR module is intended to address prevailing concerns regarding early design stage cost estimates, and offer increased transparency and fidelity by offering two preliminary perspectives on mission cost. This work outlines the existing cost model, details assumptions built into the model, and explains what measures have been taken to address the particular challenges of constellation cost estimating. The risk estimation portion of the TAT-C CR module is still in development and will be presented in future work. The cost estimate produced by the CR module is not intended to be an exact mission valuation, but rather a comparative tool to assist in the exploration of the constellation design tradespace. Previous work has noted that estimating the cost of satellite constellations is difficult given that no comprehensive model for constellation cost estimation has yet been developed, and as such, quantitative assessment of multiple spacecraft missions has many remaining areas of uncertainty. By incorporating well-established CERs with preliminary approaches to approaching these uncertainties, the CR module offers more complete approach to constellation costing than has previously been available to mission architects or Earth scientists seeking to leverage the capabilities of multiple spacecraft working in support of a common goal

Mainstream teachers\u27 experiences of communicating with students with multiple and severe disabilities

The aim of this study was to explore regular teachers\u27 perceptions and experiences of supports and obstacles to communicative interactions for students with multiple and severe disabilities (MSD). Five teachers of students with MSD participated in two in-depth interviews. Interview transcripts were analysed using content analysis. Transcripts were coded into categories, which were then grouped to yield content themes. Participants identified a broad range of themes, including: the complex needs of students with MSD, teachers\u27 training and experience, communication education for teachers, the presence of peers without disabilities, the mainstream classroom, other staff in the school context, resources, infrastructure, the culture, size and geographical location of the school, the home context, support from specialist personnel outside the school, including collaboration with speech-language pathologists, the role of government departments, and broader societal factors. There are complex, systemic influences on access to communicative interactions for students with MSD in mainstream school settings. Inadequate systemic supports restrict communicative interactions between students with MSD and their teachers and peers without disabilities, and limit the involvement of students with MSD in mainstream classroom activities. Further research is required with teachers of students with MSD to substantiate these preliminary findings

Coherent optical phase transfer over a 32-km fiber with 1-s instability at 10−1710^{-17}

The phase coherence of an ultrastable optical frequency reference is fully maintained over actively stabilized fiber networks of lengths exceeding 30 km. For a 7-km link installed in an urban environment, the transfer instability is $6 \times 10^{-18}$ at 1-s. The excess phase noise of 0.15 rad, integrated from 8 mHz to 25 MHz, yields a total timing jitter of 0.085 fs. A 32-km link achieves similar performance. Using frequency combs at each end of the coherent-transfer fiber link, a heterodyne beat between two independent ultrastable lasers, separated by 3.5 km and 163 THz, achieves a 1-Hz linewidth.Comment: 4 pages, 4 figure

eleanor: An open-source tool for extracting light curves from the TESS Full-Frame Images

During its two year prime mission the Transiting Exoplanet Survey Satellite (TESS) will perform a time-series photometric survey covering over 80% of the sky. This survey comprises observations of 26 24 x 96 degree sectors that are each monitored continuously for approximately 27 days. The main goal of TESS is to find transiting planets around 200,000 pre-selected stars for which fixed aperture photometry is recorded every two minutes. However, TESS is also recording and delivering Full-Frame Images (FFIs) of each detector at a 30 minute cadence. We have created an open-source tool, eleanor, to produce light curves for objects in the TESS FFIs. Here, we describe the methods used in eleanor to produce light curves that are optimized for planet searches. The tool performs background subtraction, aperture and PSF photometry, decorrelation of instrument systematics, and cotrending using principal component analysis. We recover known transiting exoplanets in the FFIs to validate the pipeline and perform a limited search for new planet candidates in Sector 1. Our tests indicate that eleanor produces light curves with significantly less scatter than other tools that have been used in the literature. Cadence-stacked images, and raw and detrended eleanor light curves for each analyzed star will be hosted on MAST, with planet candidates on ExoFOP-TESS as Community TESS Objects of Interest (CTOIs). This work confirms the promise that the TESS FFIs will enable the detection of thousands of new exoplanets and a broad range of time domain astrophysics.Comment: 21 pages, 13 figures, 2 tables, Accepted to PAS

Social experience does not abolish cultural diversity in eye movements.

Adults from Eastern (e.g., China) and Western (e.g., USA) cultural groups display pronounced differences in a range of visual processing tasks. For example, the eye movement strategies used for information extraction during a variety of face processing tasks (e.g., identification and facial expressions of emotion categorization) differs across cultural groups. Currently, many of the differences reported in previous studies have asserted that culture itself is responsible for shaping the way we process visual information, yet this has never been directly investigated. In the current study, we assessed the relative contribution of genetic and cultural factors by testing face processing in a population of British Born Chinese adults using face recognition and expression classification tasks. Contrary to predictions made by the cultural differences framework, the majority of British Born Chinese adults deployed "Eastern" eye movement strategies, while approximately 25% of participants displayed "Western" strategies. Furthermore, the cultural eye movement strategies used by individuals were consistent across recognition and expression tasks. These findings suggest that "culture" alone cannot straightforwardly account for diversity in eye movement patterns. Instead a more complex understanding of how the environment and individual experiences can influence the mechanisms that govern visual processing is required

Crystal structures of two one-dimensional coordination polymers constructed from Mn2+ ions, chelating hexafluoro-acetylacetonate anions, and flexible bipyridyl bridging ligands

Original Russian Text © 2016 M. J. Plater, B. M. De Silva, M. R. St. J. Foreman, W. T. A. Harrison. The text was submitted by the authors in English. Zhurnal Strukturnoi Khimii, Vol. 57, No. 6, pp. 1230-1235, July-August, 2016.Peer reviewedPostprin

Representation of Africa online: sourcing practice and frames of reference

The dominant perspective on the representation of Africa in the western media claims that western media coverage is bias and crisis orientated and the liberal perspective claims that the coverage of Africa is not as negative as is often assumed. However, there is a paucity of literature on the representation of Africa online. This research enquiry is relevant because literature claims that the Internet has the potential to resolve the journalistic predicament of representing other culture through political participation and deliberation. But this requires a re-orientation of the sourcing practice of news organization to embrace sensitivity to and knowledge of African cultures. Moreover, the journalistic predicament can be resolved or not depending on the news gathering approach adopted by the news organization. Literature has identified two approaches, that is, ‘gatekeeping’ used mainly by dominant traditional media and ‘gatewatching’ used by alternative media in their quest to counter mainstream ideology. This study examines the impacts of the ‘gatewatching’ approach adopted by Africa Have Your Say (AHYS) website on its representation and frames of reference of Africa. It uses on-site observation, in-depth interviews and textual analysis to gather data. The study found that although the sourcing practice at the AHYS is elaborate and complex, the ‘gatewatching’ approach makes its susceptible to second level agenda setting. Hence, its frame repeats the attributes and tone used by the mainstream traditional media. However, a minority of users did not use repeat this frame in their comments

Development of an eight-band theory for quantum-dot heterostructures

We derive a nonsymmetrized 8-band effective-mass Hamiltonian for quantum-dot heterostructures (QDHs) in Burt's envelope-function representation. The 8x8 radial Hamiltonian and the boundary conditions for the Schroedinger equation are obtained for spherical QDHs. Boundary conditions for symmetrized and nonsymmetrized radial Hamiltonians are compared with each other and with connection rules that are commonly used to match the wave functions found from the bulk kp Hamiltonians of two adjacent materials. Electron and hole energy spectra in three spherical QDHs: HgS/CdS, InAs/GaAs, and GaAs/AlAs are calculated as a function of the quantum dot radius within the approximate symmetrized and exact nonsymmetrized 8x8 models. The parameters of dissymmetry are shown to influence the energy levels and the wave functions of an electron and a hole and, consequently, the energies of both intraband and interband transitions.Comment: 36 pages, 10 figures, E-mail addresses: [email protected], [email protected]

Electron and hole states in quantum-dot quantum wells within a spherical 8-band model

In order to study heterostructures composed both of materials with strongly different parameters and of materials with narrow band gaps, we have developed an approach, which combines the spherical 8-band effective-mass Hamiltonian and the Burt's envelope function representation. Using this method, electron and hole states are calculated in CdS/HgS/CdS/H_2O and CdTe/HgTe/CdTe/H_2O quantum-dot quantum-well heterostructures. Radial components of the wave functions of the lowest S and P electron and hole states in typical quantum-dot quantum wells (QDQWs) are presented as a function of radius. The 6-band-hole components of the radial wave functions of an electron in the 8-band model have amplitudes comparable with the amplitude of the corresponding 2-band-electron component. This is a consequence of the coupling between the conduction and valence bands, which gives a strong nonparabolicity of the conduction band. At the same time, the 2-band-electron component of the radial wave functions of a hole in the 8-band model is small compared with the amplitudes of the corresponding 6-band-hole components. It is shown that in the CdS/HgS/CdS/H_2O QDQW holes in the lowest states are strongly localized in the well region (HgS). On the contrary, electrons in this QDQW and both electron and holes in the CdTe/HgTe/CdTe/H_2O QDQW are distributed through the entire dot. The importance of the developed theory for QDQWs is proven by the fact that in contrast to our rigorous 8-band model, there appear spurious states within the commonly used symmetrized 8-band model.Comment: 15 pages, 5 figures, E-mail addresses: [email protected], [email protected]