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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Coded-waveform design for high speed data transfer over high frequency radio channels /

Gill, Martin Christopher Unknown Date (has links)
Thesis (PhD) -- University of South Australia, 1998.
12

Estimation of a wideband fading HF channel using modified adaptive filters

Carvalho, Christopher Alan. January 1993 (has links)
Thesis (M.S.)--Ohio University, June, 1993. / Title from PDF t.p.
13

News "Outlook" in international broadcasting: a case study of Radio Australia's Connect Asia program

Xiangtao, David Wang January 2009 (has links)
The main proposition of this thesis is that the news media serve as public connectors in sustaining and stabilizing national citizens’ transnational public connection to the global public sphere. The term transnational public connection refers to civic orientation to affairs beyond national borders. This approach builds on Couldry et al.’s (2006, 2007)’s notion of nationally based “public connection”. This thesis contends that in order to fulfill such a role, the news media need to provide international news with a transnational outlook, which interprets and describes international events and affairs in relation to different countries, the region and ultimately the globe. / Considering different factors affecting international news reporting, this thesis posits that news content carried by international broadcasters would generally have a broader outlook than national news media. Hence it focused its effort on examining one type of international broadcaster: government-funded shortwave radio. This thesis argues that shortwave radio broadcasting is still relevant in today’s multimedia environment. This thesis contends that shortwave radio broadcasting functions as a crucial supplementary “external public connector” in connecting publics located in the world’s less developed regions and/or under repressive regimes to the global public sphere. Therefore it is important for them to incorporate transnational news outlook in their news reporting. / This thesis argues that shortwave radio broadcasters’ core mission of carrying out government public diplomacy does not necessarily act as an impediment to their incorporating a transnational outlook in their news reporting. It proposes that the changing notion of public diplomacy is theoretically intertwined with the concept of transnational public connection; hence it is potentially an impetus for news with transnational outlook to emerge. But for such potential to be fully realized, this thesis argues that the broadcasting stations needs to have certain levels of editorial independence and be able to balance the interests of its home country and target region in its news coverage. / Using Australia’s international shortwave broadcaster, ABC Radio Australia as a case study, this research attempts to discover whether international news with a transnational outlook could be found and to try to define the parameters of such a type of news. Operationalizing a three dimensions approach proposed by Berglez (2008) in a quantitative content analysis, this study examined news content broadcast by Radio Australia’s flagship news program Connect Asia over a period of nine weeks. It found that news with a transnational outlook does exist in Connect Asia’s news coverage and the emergence of this type of news is closely linked with news topics. This type of news is more likely to emerge in news topics such as environment and health. It also found that news with a transnational outlook comprises a very small proportion of the totality of Connect Asia’s news coverage. The frequency of such news is limited by Connect Asia’s overwhelming focus on the news topic of politics. This thesis discusses several contributory factors which resulted in Connect Asia’s overall emphasis on politics and contends that government-funded international broadcasters, as well as other international broadcasters might need to de-politicize and broaden the scope of their news coverage in order to further incorporate a transnational outlook.
14

Study of yttrium-iron-garnets (YIG) for magnetically tunable high Q VHF/UHF devices /

Zhou, Yaping, January 2000 (has links)
Thesis (Ph. D.)--University of Texas at Austin, 2000. / Vita. Includes bibliographical references (leaves 176-179). Available also in a digital version from Dissertation Abstracts.
15

Spread spectrum communication over a fading multipath HF channel using transform domain signal processing and a transmitted reference signal

Smallcomb, Joseph Michael. January 1992 (has links)
Thesis (Ph. D.)--Ohio University, November, 1992. / Title from PDF t.p.
16

Estimation of a wideband fading HF channel using modified adaptive filtering and center clipping techniques

Matherne, Marcus McLenn. January 1994 (has links)
Thesis (M.S.)--Ohio University, August, 1994. / Title from PDF t.p.
17

A real time HF beacon monitoring station for South Africa

Mudzingwa, Courage January 2009 (has links)
High frequency, HF (3 - 30 MHz), radio communications are greatly affected by ionospheric conditions. Both civilian and military users need reliable, real time propagation information to show at any time the feasibility of communicating to any part of the world on a particular frequency band. For this thesis, an automated receiving/monitoring station for the Northern California DX Foundation (NCDXF)/ International Amateur Radio Union (IARU) International Beacon Project was setup at the Hermanus Magnetic Observatory, HMO (34.42oS, 19.22oE) to monitor international beacons on 20 m, 17 m, 15 m, 12 m and 10 m bands. The beacons form a world wide multiband network. The task of monitoring the beacons was broken down into two steps. Initially the single band station, at 14.10 MHz, was installed and later it was upgraded to a multiband station capable of automatically monitoring all the five HF bands. The single band station setup involved the construction and installation of the half-wave dipole antenna, construction and installation of an HF choke balun; and the choice of Faros 1.3 as the appropriate monitoring software. The multiband monitoring station set-up involved the installation of an MFJ-1778 G5RV multiband antenna, construction and installation of a Communication Interface - V (CI-V) level converter and configuring the Faros 1.3 software to monitor the beacons on all five HF bands. Then a web page was created on the HMO space weather website (http://spaceweather.hmo.ac.za). Here, the real-time signal to noise ratio (SNR) and short path (SP)/long path (LP) plots are uploaded every 3 minutes, showing real time HF propagation conditions on the five HF bands. Historical propagation data are archived for later analysis. A preliminary data analysis was done to confirm the peration of the monitoring station. The archived data were analysed and compared to ICEPAC (Ionospheric Communications Enhanced Profile Analysis and Circuit) predictions. Results show that the real-time signal plots as well as the archive of historical signal plots, convey information on ropagation conditions to users in terms that are easy to interpret and understand.
18

Prediction and Measurement of Thermal Exchanges within Pyranometers

Smith, Amie Michelle 10 November 1999 (has links)
The Eppley Precision Spectral Pyranometer (PSP) is a shortwave radiometer that is widely used in global networks to monitor solar irradiances at the earth's surface. Within the instrument, a blackened surface is in intimate thermal contact with the hot junction of a thermopile. The cold junction of the thermopile communicates thermally with the large thermal capacitance of the instrument body, which acts as a heat sink. Radiation arrives at the blackened surface through one or two hemispherical dome-shaped filters that limit the instrument response to the solar spectrum. The voltage developed by the thermopile is then interpreted in terms of the incident irradiance. Measurements taken with the pyranometer are compared with results from theoretical models. Discrepancies between model results and measurements are used to isolate inaccuracies in the optical properties of the atmosphere used in the models. As the accuracy of the models increases, the reliability of the measurements must be examined in order to assure that the models keep up with reality. The sources of error in the pyranometer are examined in order to determine the accuracy of the instrument. Measurements obtained using the pyranometer are known to be influenced by environmental conditions such as ambient temperature, wind, and cloud cover [Bush, et al., 1998]. It is surmised that at least some of the observed environmental variability in these data is due to parasitic thermal exchanges within the instrument [Haeffelin et al., 1999]. Thermal radiation absorbed and emitted by the filters, as well as that reflected and re-reflected among the internal surfaces, influences the net radiation at the detector surface and produces an offset from the signal that would result from the incident shortwave radiation alone. Described is an ongoing effort to model these exchanges and to use experimental results to verify the model. The ultimate goal of the work described is to provide reliable protocols, based on an appropriate instrument model, for correcting measured shortwave irradiance for a variable thermal radiation environment. / Master of Science
19

On the Crest of a (Short) Wave: The Rise and Fall of International Radio Broadcasting

Dunn, Robert L. 18 May 2007 (has links)
Since 1927 international broadcasters have spanned oceans and transcended borders through the use of shortwave radio. In the beginning of the 21st century, some longtime shortwave stations have sharply cut back their English language services, particularly to North America and the Pacific region; at least one station has signed off forever. This paper examines the history of shortwave broadcasting--how it came to be, how it was used and by whom. Through interviews with broadcasters and listeners, it also explores the nature of the shortwave "experience"--especially how shortwave listening is different from listening to other media. Finally, this paper looks at what forces have precipitated such rapid and drastic changes in an 80-year old medium, why some adherents say new technologies are not necessarily suitable substitutes for shortwave, and what the near future holds for international radio broadcasting.
20

The position location of remote high frequency transmitters /

Middleton, Paul Terence. Unknown Date (has links)
Thesis (MAppSc (Research)) -- University of South Australia, 1991

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