803 research outputs found
Compendium of Applications Technology Satellite user experiments
The achievements of the user experiments performed with ATS satellites from 1967 to 1973 are summarized. Included are fixed and mobile point to point communications experiments involving voice, teletype and facsimile transmissions. Particular emphasis is given to the Alaska and Hawaii satellite communications experiments. The use of the ATS satellites for ranging and position fixing of ships and aircraft is also covered. The structure and operating characteristics of the various ATS satellite are briefly described
Disaster warning system: Satellite feasibility and comparison with terrestrial systems. Volume 2: Final report
For abstract, see Vol. 1
Pacific Basin Communication Study, volume 2
Users' meeting summary report, chronology of visits, economic data for forum countries, techniques used in the study, communication choices, existing resources in the Pacific Basin, and warc 79 region 3 rules and regulations were presented in volume 2
MST15-EISCAT18-Program
15th MST Radar Workshop (May 27-30, 2017, NIPR)18th EISCAT symposium (May 26-31, 2017, NIPR
Radio communication via near vertical incidence skywave system
Abstract. While the overall picture of our cutting-edge communication framework is one of high unwavering quality, the practical experience could be completely different during catastrophic situations, when communication services are disrupted due to damages in the communications infrastructure. Moreover, wireless connectivity in remote areas of the works is still a highly significant problem, with an estimated two billion people being outside of the connected world. This thesis studies the use of high frequencies communications as a way to address the abovementioned cases. High frequency (HF) communication utilizes radio waves between 3 and 30 MHz with the wavelengths of 100 to 10 m. The dominant means of long-distance communication in this band is skywave propagation, in which radio waves that are directed at an angle into the sky are reflected on Earth by the ionized layers of the atmosphere. HF ionospheric reflection technique is commonly used specifically for military, maritime, aeronautical, and emergency communication in remote areas, and as backup system. Factors such as season, sunspot cycle, solar activity, as well as polar aurora plays significant roles in the sustainability of HF radio communications. Propagation plays the most significant role while designing a communication network. Radio waves propagates with an objective of transmitting signal successfully without having an error. So, studies on wave propagation mechanisms, channel and noises are equally important.
This thesis focuses on high frequency near vertical incidence skywave (HF NVIS) technology. NVIS, exploiting a frequency range of 2–10 MHz, can provide continuous coverage up to a couple of hundred kilometres from the transmitter without skip zone. NVIS operation is considered during disaster relief operations when infrastructure is severely damaged or where tactical communication is needed in military operations. NVIS operation requires the presence of substantial ionization in the ionosphere directly above the transmitter. For optimizing a NVIS communication system, the most important parameters to consider are elevation angle, fading, noise and polarization. Furthermore, NVIS operation requires careful selection of antennas, operating frequency, maximum usable frequency (MUF), lowest usable frequency (LUF), as well as frequency of optimum transmission (FOT) for successful communication. At the time of emergency, low data services such as voice and text could be easily established with NVIS system. A comprehensive overview of NVIS based on number of research articles is given which highlights ionospheric propagation, antennas, the operational use of HF communications, as well as applications. Further, we highlight the challenges with possible solutions, and future research direction to ensure NVIS system sustainability. From this literature review, the significant relationship between NVIS antenna and NVIS propagation mechanism is discussed. Furthermore, thesis provides a reference text to understand various elements of NVIS system and demonstrate how modern technology can be used to solve HF issues. We believe that this article will encourage more interests in addressing the technical challenges on the research and development of future HF radio communication systems
Applications Technology Satellite and Communications Technology Satellite user experiments for 1967 - 1980 reference book, volume 1
A description of each of the satellites is given and a brief summary of each user experiment is presented. A Cross Index of User Experiments sorted by various parameters and a listing of keywords versus Experiment Number are presented
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The development of the terrestrial broadcasting networks of the United Kingdom in the twentieth century
This thesis describes an investigation into the evolution of terrestrial broadcasting -a vital new medium that has had an enormous social impact. The approach has been to concentrate upon the research and development needed to plan the intricate radio and television transmitter networks. These processes required national and international agreement on the use of the radio frequency spectrum, and the specification of many hundreds of transmitting stations. They provided the link between the broadcasters and the public, and this work presents a unique illustration of a project which dealt with many novel technical problems whilst accommodating the demands of all those concerned with the exploitation of the medium.
The UK became prominent in the field of broadcasting technology, particularly in areas concerned with propagation and service planning. The geographical position of this country between large land and sea masses, the nature of its terrain, meteorology and its population distribution, presented a wide range of distinctive problems. Research in the UK provided valuable evidence for the subsequent planning of services throughout the world, although during the rapid development of broadcasting it was impossible to examine fully all the experimental results which were produced. With resources not previously available, the author - engaged on planning work since the middle of the century - has researched evidence much of which was archived many years ago. It is not simply a work of historical interest, because new information concerning radio propagation has emerged. Its timing is also appropriate, because the beginning of the twenty-first century is witnessing revolutionary changes in broadcasting
An analysis of regulatory frameworks for wireless communications, societal concerns and risk: the case of radio frequency (RF) allocation and licensing.
This thesis analyses how and why culture and geography influence the allocation and licensing of the radio frequency (RF) spectrum in different nations. Based on a broad study of 235 countries, an inter-disciplinary approach is used to explore regulatory frameworks and attitudes toward risk. In addition, detailed case studies of the UK, France, the US and Ecuador provide deeper insights into the main contrasting regulatory styles.
Three alternative sociological theories are used to analyse and explain the results for both the in-depth and broad brush studies. The Cultural Theory of Mary Douglas and co-workers is first used to categorise countries in terms of perceptual filters. The empirical findings indicate some countries to be apparently exceptional in their behaviour. The theory of Bounded Rationality is used to investigate and explain these apparent irrationalities. Finally,
Rational Field Theory shows how beliefs and values guide administrations in their RF regulation.
A number of key factors are found to dominate and patterns emerge. The European RF harmonisation is unique. Following European unification, wireless regulation is divided into
two major camps (the EU and the US), which differ in their risk concerns, approach to top-down mandated standards, allocation of RF spectrum to licence-exempt bands and type
approval process. The adoption of cellular and TV standards around the world reflects geopolitical and colonial influence. The language of a country is a significant indicator of its analogue TV standard. Interestingly, the longitude of a country to a fair extent defines RF
allocation: Africa and West Asia follow Europe, whereas the Americas approximate the US.
RF regulation and risk tolerability differ between tropical and non-tropical climates. The collectivised/centralised versus the individualised/market-based rationalities result in different regulatory frameworks and contrasting societal and risk concerns. The success of the top-down European GSM and the bottom-up Wi-Fi standards reveal how the central-
planning and market-based approaches have thrived. Attitudes to RF human hazards and spurious emissions levels reveal that the US, Canada and Japan are more tolerant of these risks than Europe. Australia, Canada, New Zealand, UK and USA encourage technological innovation.
A practical benefit of this study is that it will give regulators more freedom to choose a rational RF licensing protocol, by better understanding the possibly self-imposed boundaries of cultural and geographical factors which are currently shaping allocation. Academically, there is utility in undertaking a cultural and geographic analysis of a topic that is mostly the domain of engineering, economic and legal analysts
Satellite technology in the maritime world : applications and implications
This dissertation is a study of the widespread utilization of satellite technology in the maritime world, with particular reference to the applications and implications of communication, navigation and remote sensing satellites to shipping and other maritime related fields. A brief look is taken at the general background of satellite technology, including the growth and development and basic techniques as well as categorization of applications. This is followed by a more detailed view of the three different areas of the applications of satellite technology, namely maritime communications, marine navigation and maritime meteorology and oceanography. The two well-known satellite-based systems, the INMARSAT System and the Global Positioning System, are both widely used by the maritime community and thus emphasized in this study. Apart from a brief description of those two systems, their applications are examined, their impact on the marine industry is discussed and their future development is investigated in order to obtain an appreciation of their role in the present maritime world. The applications of remote sensing satellites in marine meteorology and oceanography are also discussed. In addition to the above, the impact of the increasing use of satellite technology on maritime education and training is investigated. The concluding chapter is a summary of the main points discussed in the core chapters, which reflect the author’s viewpoin
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