The Conformal C-Band/Multi-band Antenna project will support the AWS-3 auction by providing the technology to integrate C-Band or multi-band telemetry(TM) antennas on test articles such as missiles, weapons, or aircraft. These test articles would then provide C-Band or multi-band TM data to ground station receivers that are relocated to the C-Band frequency range through the AWS-3 Spectrum Relocation Fund program. This project would advance the technology of antennas in the C-Band region for test article TM integration. Successful use of C-Band and Multi-Band antennas for aeronautical mobile telemetry (AMT) on test and training ranges is dependent on the advancement of key technologies. This paper will detail the technology areas being matured by this project as well as the capabilities to be demonstrated.

From the remarks made by the then Secretary General of ITU, one envisions the possibilities of a truly connected world and upholding of tenets prescribed in the Outer Space Treaty of 1967, which provides for all of outer space, including the Geostationary orbit, as the province of all mankind, to be used for the benefit and in the interests of all countries, irrespective of their degree of economic or scientific development.2 On the backbone of ‘connecting the world’ is the scarce resource, spectrum, which is managed and allocated to states by the International Telecommunications Union (ITU). The demand for radio-based applications has been growing in line with the increasing mobility across the globe. Radio spectrum is a major global asset contributing substantial value to economies of states, whether big or small, and underlines critical aspects of their citizens’ lives. Radio communications is critical to areas such as air travel, emergency services, telecommunications, sound and television broadcasting, military defence, space research and other scientific activities Spectrum plays a very critical role in the economic development of any society as it brings connectivity, it even plays a critical role in developing economies as it serves in bridging the existing “digital divide”. However, this precious commodity is a scarce resource, the available radio spectrum is limited.4 The rapidly changing environment of electronic communications, impressive technological progress, convergence and changing habits of end-users’ consumption is creating pressure for existent spectrum as well as its regulation and management. This has necessitated the need for managing a new, previously unused, international resource – the satellite spectrum/orbit., which is becoming increasingly crowded. At the same time, the increasing use of lower Earth orbits is further increasing the need for international coordination. ITU plays a crucial role in ensuring that operators’ multimillion dollar satellite systems operate smoothly throughout their lifetimes, delivering services to billions of people without interfering with each other. The space-faring states are demanding more spectrum as they increase activities in outer space due to technological advancements, however, at what cost to the non-space faring states. At the same time the ITU is burdened with the responsibility of trying to harmonise the use of spectrum bands across the globe between the space-faring and upcoming non-space faring states, mainly the developing countries. The objective of this research is to ascertain whether, given the rapid technological changes being experienced across the globe, the ITU is still sufficient in its current state, to adequately manage and regulate the allocation of spectrum to all states, maintaining the true spirit of the principle of ‘province of all mankind’. Bearing in mind the ever increasing demands of advanced economies over the gradually increasing demands of developing economies and the concept of geostationary orbit being for the benefit of all countries irrespective of their degree of economic or scientific development. countries’. It is against this background that this thesis seeks to address the following question “The role of the International Telecommunications Union in Outer Space Spectrum management with respect to developing nations”. The author will tackle this research through a quantitative lens, making use of the desktop methodology because of the nature of the research topic. A significant amount of reading will need to be done around the legal framework governing the ITU with regards to space technology. This thesis is mainly based on secondary data, retrieved from official documents, reports, news articles, academic papers and books. The research will take upon the characteristics of being critical to current legislative frameworks as well as the role of the ITU in the management and allocation of spectrum. It will be essential for the author to look at the historical legislature and how it has gradually progressed into what is currently obtaining. The thesis will take a critical approach in order to interrogate the relevance of the ITU in today’s modern era in light of the provisions of the Outer Space Treaty and the various ITU regulations particularly the ITU Convention; ITU Constitution and the ITU Radio Regulations in spectrum management and allocation including the position of developing states. / Mini Dissertation (LLM)--University of Pretoria, 2019. / Public Law / LLM / Unrestricted

The near ultraviolet absorption spectra of cyclohexanone, cyclohexanone α, α, α', α'd₄ and cyclohexanone d₁₀ have been recorded and analysed under low and high resolution. The vibrational and rotational structure accompanying the electronic singlet-singlet ṉ→π* transition have been analysed. Some complementary information has been obtained from the infrared vapour spectrum of cyclohexanones. The geometries of the ground and first excited state have been determined. In the excited state configuration, the oxygen atom was bent out of the plane of the three adjacent carbon atoms by about 30º, and the carbon oxygen bond increases by 0.08 Å between the ground state and the excited state. Some ring modes are strongly active in the electronic spectra of the three isomers. This may indicate some coupling between the carbonyl group and the ring. The results obtained by band contour analysis are consistent with those obtained by calculation of a double minimum potential function, as well as those obtained in previous work on related molecules. / Thesis / Master of Science (MSc)

Master of Science / The 6 GHz spectrum band (5.925 GHz – 7.125 GHz) is an important frequency range for many industries due to its high bandwidth capabilities, low latency, and ability to support high data transfer rates. Different types of services, both fixed and mobile, are utilizing the 6 GHz frequency band at present. The incumbents of this band comprise governmental and commercial entities that depend on the 6 GHz spectrum for services like transportation and public safety. The 6 GHz spectrum has also been identified for use by various wireless communication systems, including Wi-Fi, Bluetooth, and 5G. Incumbent licensed operators need to be able to access the spectrum without significant interference to operate effectively. As more wireless communication systems are developed and deployed, the demand for spectrum continues to grow. There is a need for spectrum sharing due to the scarcity of coverage-friendly low band spectrum. Indeed, 6G is expected to use spectrum sharing to a much larger extent compared to previous generations of wireless systems. This thesis provides extensive experimentation results using a commercial FML system that can be used to understand resiliency of FML receivers to interference at 6 GHz.

No description available.

Cognitive radio had been proposed as a methodology for overcoming the inefficiency of the conventional static allocation of the available spectrum in wireless communication networks. The majority of opportunistic spectrum access schemes in cognitive radio networks (CRNs) rely on the Listen-Before-Talk (LBT) model due to the half-duplex nature of conventional wireless radios. However, LBT su ers from the problem of high collision rates and low secondary user throughput if time is misaligned among the secondary users (SUs) and the primary users (PUs). This problem can be mitigated by leveraging full-duplex (FD) communications that facilitate concurrent sensing and transmission. This thesis considers the problem of optimal opportunistic multi-channel spectrum sensing and access using FD radios in the presence of uncertain primary user (PU) activity statistics. A joint learningand spectrum access scheme is proposed. To optimize its throughput, the SU sensing period has to be carefully tuned. However, in absence of exact knowledge of the PU activity statistics, the PU's performance may be adversely a ected. To address this problem, a robust optimization problem is formulated. Analysis shows that under some non-restrictive simplifying assumptions, the robust optimization problem is convex. The impact of sensing periods on the PU collision probability and the SU throughput are analyzed, and the optimal sensing period is found via convex optimization. An "\epsilon-greedy algorithm is proposed for use by the SU to learn the PUs' activity statistics in multichannel networks. It is shown that sublinear regrets can be attained by the proposed estimation and robust optimization strategy. Simulation studies demonstrate that the resulting robust solution achieves a good trade-o between optimizing the SU's throughput and protecting the PU. / Thesis / Master of Applied Science (MASc)

Modern innovation is a driving force behind increased spectrum crowding. Several studies performed by the National Telecommunications and Information Administration (NTIA), Federal Communications Commission (FCC), and other groups have proposed Dynamic Spectrum Access (DSA) as a promising solution to alleviate spectrum crowding. The spectrum assignment decisions in DSA will be made by a centralized entity referred to as as spectrum access system (SAS); however, maintaining spectrum utilization information in SAS presents privacy risks, as sensitive Incumbent User (IU) operation parameters are required to be stored by SAS in order to perform spectrum assignments properly. These sensitive operation parameters may potentially be compromised if SAS is the target of a cyber attack or an inference attack executed by a secondary user (SU). In this thesis, we explore the operational security of IUs in SAS-based DSA systems and propose a novel privacy-preserving SAS-based DSA framework, Suspicion Zone SAS (SZ-SAS), the first such framework which protects against both the scenario of inference attacks in an area with sparsely distributed IUs and the scenario of untrusted or compromised SAS. We then define modifications to the SU inference attack algorithm, which demonstrate the necessity of applying obfuscation to SU query responses. Finally, we evaluate obfuscation schemes which are compatible with SZ-SAS, verifying the effectiveness of such schemes in preventing an SU inference attack. Our results show SZ-SAS is capable of utilizing compatible obfuscation schemes to prevent the SU inference attack, while operating using only homomorphically encrypted IU operation parameters. / Master of Science / Dynamic Spectrum Access (DSA) allows users to opportunistically access spectrum resources which were previously reserved for use by specified parties. This spectrum sharing protocol has been identified as a potential solution to the issue of spectrum crowding. This sharing will be accomplished through the use of a centralized server, known as a spectrum access system (SAS). However, current SAS-based DSA proposals require users to submit information such as location and transmission properties to SAS. The privacy of these users is of the utmost importance, as many existing users in these spectrum bands are military radars and other users for which operational security is pivotal. Storing the information for these users in a central database can be an major privacy issue, as this information could be leaked if SAS is compromised by a malicious party. Additionally, malicious secondary users (SUs) may perform an inference attack, which could also reveal the location of these military radars. In this thesis, we demonstrate a SAS-framework, SZ-SAS, which allows SAS to function without direct knowledge of user information. We also propose techniques for mitigating the inference attack which are compatible with SZ-SAS

No / Raman spectroscopy is a rapid nondestructive technique providing spectroscopic and structural information on both organic and inorganic molecular compounds. Extensive applications for the method in the characterization of pigments have been found. Due to the high sensitivity of Raman spectroscopy for the detection of chlorophylls, carotenoids, scytonemin, and a range of other pigments found in the microbial world, it is an excellent technique to monitor the presence of such pigments, both in pure cultures and in environmental samples. Miniaturized portable handheld instruments are available; these instruments can be used to detect pigments in microbiological samples of different types and origins under field conditions.

The ultrasonic NDE technique to characterize the ultrasonic nonlinear response of the cyclically load 7075-T6 aluminum is described in this thesis. In order to estimate the nonlinear relation of the ultrasonic waves due to material fatigue damage or degradation, the spectral analysis techniques such as the power spectrum, bispectrum, and bicoherence spectrum are applied. The ultrasonic nonlinearity parameters by Cantrell and Jhang are introduced and presented as a function of the material fatigue growth, the number of fatigue cycles. This thesis presents the effectiveness of the bispectral analysis for evaluating the nonlinear aspects of the ultrasonic wave propagation. The results show that the nonlinearity parameters by Cantrell and Jhang are responsive to the output amplitude of the received signal and vary for the various materials, and independent of the input frequency and the ultrasonic wave propagation distance. By using the bispectral analysis tools, particularly the bicoherence spectrum, the increase of the coupling levels between the fundamental, its harmonic, and subharmonic frequency components is presented as the number of fatigue cycles is increased. This thesis suggests that the application of the bicoherence spectrum based on the nonlinear wave coupling relations be more effective for estimating the level of the material fatigue life. / Master of Science

A procedure of multispectral analysis was developed to classify a two category image. The procedure utilized pattern recognition and feature extraction techniques. Images were acquired using a computer vision system with a series of interference filters to limit the wavelength band of the images. The procedure developed for multispectral analysis is: (1) Filter selection and image acquisition. (2) Pattern recognition. (3) Bayes minimum error rate classification. (4) Feature extraction by Fisher transformation or by Hotelling transformation. The analytical procedure was programmed in Microsoft C computer language and implemented on an IBM AT computer. The system was tested by identifying an apple against a Formica background. The classified images and histograms indicated that the separation was possible.