Thesis (Master of Engineering in Electrical Engineering)--Cape Peninsula University of Technology, 2017. / This dissertation presents the development of a quadrature phase shift keying (QPSK) demodulator for nanosatellites that complies with both the limited resources associated with nanosatellites as well as the flexibility and configurability required for a software defined radio (SDR) platform. This research project is a component of a bigger project, which is to develop a high-speed receiver for nanosatellites, and aims to provide a practical solution to the need for communication technologies that support emerging nanosatellite applications, such as Earth observation and communications. The development of the QPSK demodulator follows an all-digital implementation approach. The main reason for selecting this approach is to have a system that is flexible and reconfigurable to comply with the SDR requirements. Another reason for selecting this approach is to comply with the low noise system, low power consumption as well as the small size and weight requirements associated with nanosatellites. The QPSK demodulator is implemented on an IGLOO2 Field Programmable Gate Array (FPGA), due to its robustness to radiation and high-speed capability. Initially, the techniques used to design each subsystem of the QPSK demodulator are selected. Then, algorithms to digitally implement the designed subsystems are produced. Thereafter, the code for the digital QPSK demodulator is written and verified in Matlab first. The simulation of the Matlab-based QPSK demodulator performs satisfactorily. Subsequently, the code to implement the QPSK demodulator on an FPGA (IGLOO2) has been written in Libero, using VHSIC Hardware Description Language (VHDL). The resulting FPGA-based QPSK demodulator has been emulated in Libero (an integration and development environment (IDE) for Microsemi FPGAs) using a test-bench as well as other analysis tools. The test-bench results are visualized using Modelsim. The results show that the demodulator can support data rates up to 13.25 Mbps if 16 samples-per-symbols are used, and up to 26.5 Mbps if 8 samples-per-symbols are used. It also has a very good bit-error-rate performance, which is simulated to be within a factor of 5 of the theoretical limit of QPSK modulation. Finally, the demodulator consumes less than 15 mW at the maximum operating speed. and has been coded to mitigate the effects of space radiation and noise contriution by the demodulator itself.

published_or_final_version / abstract / toc / Electrical and Electronic Engineering / Master / Master of Philosophy

In this thesis, novel error rate performance metrics and transmission solutions are investigated for delay limited communication systems and for co-channel interference scenarios. The following four research problems in particular were considered. The first research problem is devoted to analysis of the higher order ergodic moments of error rates for digital communication systems with time- unlimited ergodic transmissions and the statistics of the conditional error rates of digital modulations over fading channels are considered. The probability density function and the higher order moments of the conditional error rates are obtained. Non-monotonic behavior of the moments of the conditional bit error rates versus some channel model parameters is observed for a Ricean distributed channel fading amplitude at the detector input. Properties and possible applications of the second central moments are proposed. The second research problem is the non-ergodic error rate analysis and signaling design for communication systems processing a single finite length received sequence. A framework to analyze the error rate properties of non-ergodic transmissions is established. The Bayesian credible intervals are used to estimate the instantaneous bit error rate. A novel degree of ergodicity measure is introduced using the credible interval estimates to quantify the level of ergodicity of the received sequence with respect to the instantaneous bit error rate and to describe the transition of the data detector from the non-ergodic to ergodic zone of operation. The developed non-ergodic analysis is used to define adaptive forward error correction control and adaptive power control policies that can guarantee, with a given probability, the worst case instantaneous bit error rate performance of the detector in its transition fi'om the non-ergodic to ergodic zone of operation. In the third research problem, novel retransmission schemes are developed for delay-limited retransmissions. The proposed scheme relies on a reliable reverse link for the error-free feedback message delivery. Unlike the conventional automatic repeat request schemes, the proposed scheme does not require the use of cyclic redundancy check bits for error detection. In the proposed scheme, random permutations are exploited to locate the bits for retransmission in the predefined window within the packet. The retransmitted bits are combined using the maximal-ratio combining. The complexity-performance trade-offs of the proposed scheme is investigated by mathematical analysis as well as computer simulations. The bit error rate of the proposed scheme is independent of the packet length while the throughput is dependent on the packet length. Three practical techniques suitable for implementation are proposed. The performance of the proposed retransmission scheme was compared to the block repetition code corresponding to a conventional ARQ retransmission strategy. It was shown that, for the same number of retransmissions, and the same packet length, the proposed scheme always outperforms such repetition coding, and, in some scenarios, the performance improvement is found to be significant. Most of our analysis has been done for the case of AWGN channel, however, the case of a slow Rayleigh block fading channel was also investigated. The proposed scheme appears to provide the throughput and the BER reduction gains only for the medium to large SNR values. Finally, the last research problem investigates the link error rate performance with a single co-channel interference. A novel metric to assess whether the standard Gaussian approximation of a single interferer underestimates or overestimates the link bit error rate is derived. This metric is a function of the interference channel fading statistics. However, it is otherwise independent of the statistics of the desired signal. The key step in derivation of the proposed metric is to construct the standard Gaussian approximation of the interference by a non-linear transformation. A closed form expression of the metric is obtained for a Nakagami distributed interference fading amplitude. Numerical results for the case of Nakagami and lognormal distributed interference fading amplitude confirm the validity of the proposed metric. The higher moments, interval estimators and non-linear transformations were investigated to evaluate the error rate performance for different wireless communication scenarios. The synchronization channel is also used jointly with the communication link to form a transmission diversity and subsequently, to improve the error rate performance.

The number of digital projects aimed at documenting and preserving communities' intangible cultural heritage (ICH) has grown considerably in recent years. These projects take advantage of the advancement of digital technologies to enable local communities to manage their ICH, in tune with the deprofessionalisation of heritage practices. However, additional work is needed to overcome some of the barriers that are emerging in these endeavours, especially related to long-term sustainability and the technical knowledge required. The thesis follows the progress of two case studies that used wikis to enable participation in the documentation of cultural heritage. Using action research, the researcher introduced or tried to improve the use of wikis in these case studies. The first case study involved a Scottish heritage wiki at a national level, but the project ran into many problems. Although the software was appropriate for facilitating public engagement, the research showed that the emphasis should be put on local heritage rather than national, and that face-to-face interactions providing engagement and training activities should have been more widely used as well. The second case study was the analysis of a wiki dedicated to collating and documenting the ICH of the Isle of Jura, Scotland. The problems encountered in this case study point to the presence of pre-existing conflicts and the contentious nature of heritage on the island as barriers to the project. The main argument of the thesis is that involvement in digital cultural heritage can enhance community empowerment, but that this depends upon social dimensions of community cohesion and engagement as well as technical knowledge of the software and technologies involved.

ME|EMO provides a method to help users to express, visualize and share emotions through digital nonverbal communication. This application will enable the users to map their emotions to colors and encourage users to paint their feelings. A canvas with uncolored images and a color palette with color coded emotions creates an environment for expressing and visualizing the feelings. The result is an image file in the form of a simple piece of modern art with the possibility of sharing it through social networks, or to record the emotions and save precious moments of life. Technology development, new ways of communication, digital tools, apps, social media, have helped people to have a better life by giving people the opportunity to communicate easier with loved ones and friends. ME|EMO tries to enhance the way of modern communication (digital text-based) such as social networks or modern healthcare systems, by supporting the emotional side of communications.

En la actualidad, el Perú ocupa el puesto número 65 de un total de 140 países a nivel mundial, con respecto al tiempo que le dedica la población al voluntariado (CAF, 2018). Además, en Europa, se ha presentado un estancamiento durante los últimos cinco años: África un incremento de 2% y, finalmente, Asia, Oceanía y América un decrecimiento de 2%, 1% y 2%, respectivamente (CAF, 2018). Según este panorama, el voluntariado a nivel mundial presenta un decrecimiento alarmante debido a la carencia de personal voluntario que apoye a las organizaciones e instituciones sin fines de lucro. Con la presente investigación se busca encontrar la relación entre las variables comunicación digital e influencers con la captación online de voluntarios, con la finalidad de que las organizaciones sin fines de lucro puedan considerarlas durante su proceso de captación de manera eficiente. Para lograr lo mencionado se utilizaron técnicas de recolección de datos de tipo cualitativos y cuantitativos. El presente estudio se centrará en voluntarios jóvenes, con un rango de edad entre los 15 y 29 años, y que participan de manera activa en una organización sin fines de lucro. Cabe mencionar que los resultados de esta investigación podrán ser generalizados a toda organización, institución o empresa que cuente con voluntarios. / Currently, Peru occupies the 65th position of a total of 140 countries worldwide, with respect to the time the population dedicates to volunteering (CAF, 2018). In addition, in Europe, there has been a stagnation during the last five years: Africa an increase of 2% and, finally, Asia, Oceania and America a decrease of 2%, 1% and 2%, respectively (CAF, 2018). According to this scenario, worldwide volunteering shows an alarming decrease due to the lack of volunteer staff that support nonprofit organizations and institutions. This research seeks to find the relationship between the variables digital communication and influencers with the online recruitment of volunteers, so that non-profit organizations can consider them during their recruitment process efficiently. To achieve the aforementioned qualitative and quantitative data collection techniques were used. The present study will focus on young volunteers, with an age range between 15 and 29 years, and who actively participate in a non-profit organization. It should be mentioned that the results of this research may be generalized to any organization, institution or company that has volunteers. / Trabajo de investigación

Los medios tradicionales de la comunicación como la prensa escrita, la radio y la televisión han incorporado nuevas modalidades para la producción de sentido y la difusión de información, que son algunas de las características de la comunicación digital. De este modo se han creado diferentes canales web que desarrollan contenido audiovisual de carácter periodístico sobre temas de actualidad, política, sociedad, economía y cultura. Exitosa Noticias TV, por ejemplo, se ha convertido en un medio de comunicación multiplataforma que utiliza los canales web y la plataforma live streaming para difundir sus programas de televisión. Así también se encuentra RTV La República, un canal web reciente, pero de histórico formato en prensa escrita que utiliza este espacio digital para desarrollar y publicar nuevos contenidos de todo ámbito de información. En la presente investigación se realiza un análisis comparativo sobre la construcción del discurso periodístico en estos dos canales web durante un mismo contexto electoral. Teniendo en cuenta ello, se desarrolla un análisis de la cobertura electoral, las estrategias discursivas y los elementos del lenguaje periodístico y audiovisual. El objetivo es identificar de qué manera construyen sus discursos periodísticos los canales web RTV La República y Exitosa Noticias durante la cobertura electoral municipal Lima 2018. Los programas políticos de opinión y de entrevistas son el objeto de estudio de este análisis. / Traditional media such as the written press, radio and television have incorporated new modalities for the production of meaning and the dissemination of information, which are some of the characteristics of digital communication. In this way, different web channels are created that develop audiovisual content of a journalistic nature on current affairs, politics, society, economy and culture. Exitosa Noticias TV, for example, has become a cross-platform means of communication that uses web channels and the live streaming platform to broadcast its television programs. Likewise, there is RTV La República, a recent web channel, but of a historical format in the written press, which uses this digital space to develop and publish new content in all areas of information. In the present investigation, a comparative analysis is carried out regarding the construction of the journalistic discourse in these previously mentioned web channels, during the same electoral context. Taking this into account, an analysis of electoral coverage, discursive strategies and elements of audiovisual journalistic language is developed. The objective is to identify how the RTV La República and Exitosa Noticias TV web channels built in Lima 2018 municipal electoral coverage, their political opinion and interview programs being the object of study of this analysis. / Tesis

Omställningen till ett digitalt arbetsliv, till följd av Covid-19-pandemin, på distans har förändrat många människors sätt att arbeta de senaste två åren. Forskning visar på motstridiga resultat hur distansarbetare upplever detta sätt att arbeta och det finns en bristande kunskap om hur kommunikationen inom de digitala plattformarna påverkar distansarbetarnas upplevelse av KASAM. Syftet var att undersöka om distansarbetare, som innan pandemin inte tidigare arbetat på distans, upplever att kommunikation via digitala plattformar påverkar deras upplevelse av KASAM. I studien deltog 12 respondenter från både offentlig och privat sektor. Genom kvalitativa semistrukturerade intervjuer, som analyserades tematiskt, visade resultatet att respondenterna upplevde både faktorer som hindrade KASAM, som bland annat försämrad teamkänsla, och faktorer som främjade KASAM, som bland annat ökad effektivitet. Studiens resultat visade i linje med vad tidigare forskning sagt att det finns både positiv och negativ påverkan på respondenternas KASAM när de kommunicerar via digitala plattformar under distansarbete.

<p> The problem of communication would have been trivial if the channel through which the signal must propagate were ideal, that is, an all pass system with a linear phase response. In practice, channels are non-ideal; imperfections in the physical channel, such as time-dispersion and frequency-dispersion, are the results of signal dependent distortions. In addition, upon reception the signal is further corrupted by the inevitable presence of additive random noise. Time dispersion causes successive pulses to overlap, thereby creating a phenomenon which has been termed 'intersymbol interference'. Frequency dispersion causes the received signal spectrum to vary both in amplitude and phase. Unless these channel imperfections are taken into account in the design of the communication system, the rate of data transmission can be limited by the physical channel. Also, the presence of additive noise poses further limitations on the ultimate performance of the system.</p> <p> This thesis is concerned with adaptive signal processing techniques for digital communication through dispersive unknown channels. The research undertaken has been principally aimed at the analytical derivations of an adaptive recursive filter and an adaptive recursive equalizer, and the simulations of overall binary communication systems, taking into account dispersive effects as well as random noise.</p> <p> Computer simulation tests have indicated that the new adaptive equalizer exhibits a much more robust operation capability and improved system performance than the conventional adaptive equalizer. This study has indicated that adaptive signal processing is a viable technique upon which a reliable communications system may be designed.</p> / Thesis / Doctor of Philosophy (PhD)

Digital communication has shifted the way that communication takes place for many companies. The amount of technological communication platforms and tools available are high and are also still increasing which also entails that many companies have several ways to communicate available. Organizational decisions and Management incentives to adopt new platforms and tools for communication are in advance also influencing employees and middle managers in their day-to-day work. Research has in this manner highlighted managerial strategies to handle the implementation of technology in general and further pointed out how both technology and digital communication can influence employees in companies' different processes. Even though there is a vast amount of research about digital communication done, there is a general need for further research about the extensive amount of digital communication solutions available. A gap in earlier research was further seen as digital communication in the sales process in the national context of Sweden is lacking research. The sales process in this manner is one of the main processes within many companies that are seen to be affected by the implementation of digital communication. However, a deeper understanding of the employees and middle managers perspective is seen to be needed. To gain further insights and to shed light on the area of digital communication in a Swedish context, the influences that digital communication have on employees and middle managers are investigated, further the rationale behind using digital communication within the sales process is also studied. The empirical data that is collected through qualitative studies by conducting semi- structured interviews provided us with findings that shows three main positive influences and two main negative influences that digital communication has on the employees and middle managers within the company at hand. The positive influences can be summarized as, the convenience with using digital communication, the flexibility of location and the valuable information to be found on the platform and tools. The negative influences on the other hand were seen to be, the amount on communication channels and the inconvenience with finding information. Following the main aspects found with the rationale behind using digital communication within the sales process were identified to be, the perceived management reasoning &amp; support, educational opportunities, ambassadors and varying use depending on work task. Both the influences and the rationale are then visualized in a model to simplify the main findings. The theoretical contributions of this study can facilitate a further understanding of digital communication. Further the study can provide managers with insights on how eventual implementations of digital communication may influence the workforce. Finally the empirical data can contribute to a broader overall understanding of digital communication. However, further research is necessary within this field to gain a more holistic view of the subject at hand.