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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.
191

A TRADE STUDY TO DETERMINE THE BEST LOCATION FOR TM RECEIVERS

Diehl, Michael, Fraser, Ryan, Green, Jonathan, Swain, Jason 10 1900 (has links)
As part of a larger effort to improve telemetry link availability, the U.S. Army Yuma Proving Ground (YPG) is currently in the process of upgrading its telemetry receivers. As YPG begins integrating new receivers into existing range infrastructure, the question of where to place these receivers to provide maximum benefit must be considered. Should the receivers be placed at each of the remote antennas or should they be centrally located at the primary telemetry site? Although many Telemetry-over-Internet Protocol (TMoIP) and radio frequency (RF) over fiber solutions exist to transport these data, there are numerous concerns including network and Cybersecurity limitations to consider when implementing either of these approaches. This paper will document the trade study conducted at YPG to explore the benefits of each approach.
192

Design of substrate integrated waveguide H-plane horn antenna with symmetric beamwidths

Iqbal, Farzeen 16 August 2017 (has links)
Millimeter-wave Substrate Integrated Waveguide (SIW) technology presents itself as the most viable solution for the development of RF systems. It is a cost-e ective solution, suitable for mass production of such systems. Like planar circuits, SIW structures are compact, light weight and easy to fabricate. They also preserve some of the major advantages of metallic waveguides, namely, low loss, high quality factor and high power handling capabilities. In RF systems, rectangular waveguide horns have found various applications due to their exceptional radiation properties. From their simple construction, ease of ex- citation, usefulness and high gain, they are readily used as feed component in various RF systems, they also aid as the standardization for calibration and gain measure- ments of other high gain antennas. We are aware that, in an H-plane horn antenna, the rectangular waveguide is flared in the direction of the H-field. A large aperture in the H-plane presents the narrower half power beamwidth whereas a small aperture in the E-plane gives a wider beamwidth. In this research, the design of a SIW H- plane horn antenna with approximately symmetric half power beamwidths in both the E- and H-planes is proposed, using the commercially available electromagnetic field solver CST Microwave Studio to design and simulate proposed antenna characteristics and performance. Also, radiation patterns are analyzed and in order to validate the simulation results, measurements are performed on a fabricated prototype antenna. / Graduate
193

Radio frequency propagation differences through various transmissive materials.

Ryan, Patrick L. 12 1900 (has links)
The purpose of this research was to determine which of the commonly used wireless telecommunication site concealment materials has the least effect on signal potency. The tested materials were Tuff Span® fiberglass panels manufactured by Enduro Composite Systems, Lexan® XL-1 polycarbonate plastic manufactured by GE Corporation and Styrofoam™ polystyrene board manufactured by The Dow Chemical Company. Testing was conducted in a double electrically isolated copper mesh screen room at the University of North Texas Engineering Technology Building in Denton, Texas. Analysis of the data found no differences exist between the radio frequency transmissiveness of these products at broadband personal communication service frequencies. However, differences in the signal do exist with regards to the angle of incidence between the material and the transmitting antenna.
194

A Radio Frequency Mass Spectrometer

Kerr, John 10 1900 (has links)
This thesis describes a non-magnetic mass spectrometer incorporating the following components: a heated filament source, an electrostatic energy analyser, and a time-of-flight velocity analyser. The last component measures the time required for an ion to go between two small condensers by means of a radio frequency voltage applied to the condensers. If an ion passes successively through both condensers when the field in them is zero, it is collected and detected. It is then possible to relate the e/m to the frequency of the applied voltage when the energy of the ion and the distance between the centres of the condensers is known. Theory is presented which permits the calculation of resolution and current intensities. The values so obtained are realized experimentally. / Thesis / Master of Science (MSc)
195

IMPROVING INTEROPERABILITY OF GPS AND LBAND TELEMETRY WITH SHAPED-PATTERN ANTENNAS

Richen, Andrew, Clark, David, McNamee, Stuart, Ellington, Robert, Johnson, Gary, Williams, Guy, Selbrede, Robert 10 1900 (has links)
International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, Nevada / In a study sponsored by the Air Force Flight Test Center at Edwards AFB, California, Toyon Research Corporation, Goleta, California, demonstrated that shaped pattern antennas could be used to mitigate interference caused by telemetry signals on GPS systems. Using a technique for fixed reception pattern antenna (FRPA) design, Toyon built and tested a GPS antenna that minimizes reception of telemetry signals from a known location.
196

Performance analysis of hybrid optical wireless and radio frequency communication systems

Rakia, Tamer 28 July 2016 (has links)
In this thesis, we analyze the performance of heterogeneous wireless communication systems that are composed of Optical Wireless Communication (OWC) and Radio Frequency (RF) systems. OWC systems further include long range outdoor Free Space Optical (FSO) systems and short range indoor Visible Light Communication (VLC) systems. Hybrid FSO/RF systems have emerged as a promising solution for high data rate wireless transmissions. Various transmission schemes including switch-over and soft-switching had been presented for hybrid FSO/RF systems. To overcome the drawbacks of existing schemes, we present a new transmission strategy for hybrid FSO/RF systems exploring an adaptive combining technology. This new strategy shows an improved outage performance. Typically, when the transmitter and the receiver are provided with channel state information, the transmission schemes can be adaptively designed allowing the channel to be used more efficiently. We present two new joint adaptive transmission schemes for hybrid FSO/RF systems. The first one is joint adaptive modulation and adaptive combining scheme which improves the spectral efficiency of hybrid FSO/RF systems. The other one is joint power adaptation and adaptive combining scheme which improves the throughput and the outage performance of hybrid FSO/RF systems. We accurately evaluate the performance of both schemes. FSO technology can be used effectively in multiuser scenarios to support Point-to-Multi-Point (P2MP) networks. In P2MP networks, FSO links are used for data transmission from a central location to multiple users. In this thesis, we present a new P2MP network based on hybrid FSO/RF transmission system. A common backup RF link is used by the central station for data transmission to any user in case of the failure of its corresponding FSO link. Based on a Markov Chain formulation, we study the performance of the resulting system. P2MP Hybrid FSO/RF network achieves considerable performance improvement over the P2MP FSO-only network. In VLC, Light Emitting Diode (LED) is used for the purpose of simultaneous illumination and data communication at high data rate. However, the light originating from a LED source is naturally confined to a small area and is susceptible to blockages. Hybrid VLC/RF systems have been emerged as a promising solution to provide enhanced communication coverage. We introduce a new dual-hop VLC/RF system with energy harvesting relay to extend the coverage of indoor wireless system based on VLC. The second-hop RF transmission uses the harvested energy over the first-hop VLC transmission. In this thesis, we propose two different approaches for energy harvesting at the relay terminal. In the first approach, the relay harvests light energy from different artificial light sources and sunlight entering the room. In this approach, we propose a novel statistical model for the harvested electrical power and analyze the probability of data packet loss. In the second approach, the relay harvests energy from the VLC link by extracting the direct current component of the received optical signal. In this approach, we investigate the optimal design of the hybrid VLC/RF system in terms of data rate maximization. In both cases, we present extensive numerical examples to define important design guide lines for VLC/RF systems. / Graduate
197

STANDARD INTEROPERABLE DATALINK SYSTEM, ENGINEERING DEVELOPMENT MODEL

Cirineo, Tony, Troublefield, Bob 11 1900 (has links)
International Telemetering Conference Proceedings / October 30-November 02, 1995 / Riviera Hotel, Las Vegas, Nevada / This paper describes an Engineering Development Model (EDM) for the Standard Interoperable Datalink System (SIDS). This EDM represents an attempt to design and build a programmable system that can be used to test and evaluate various aspects of a modern digital datalink. First, an investigation was started of commercial wireless components and standards that could be used to construct the SIDS datalink. This investigation lead to the construction of an engineering developmental model. This model presently consists of wire wrap and prototype circuits that implement many aspects of a modern digital datalink.
198

TELEMETRY AND RADIO FREQUENCY IDENTIFICATION

Heikkinen, Jouko 10 1900 (has links)
International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / Comparison of short-range telemetry and radio frequency identification (RFID) systems reveals that they are based on very similar operating principles. Combining the identification and measurement functions into one transponder sensor offers added value for both RFID and telemetry systems. The presence of a memory (e.g. FRAM) in the transponder, required for ID information, can also be utilized for storing measurement results. For passive transponders low power consumption is one of the main objectives. Wireless power transfer for passive transponder sensors together with above aspects concerning a combined telemetry and identification system are discussed.
199

Bandwidth-efficient pilot-symbol-aided techniques for fading estimation in multipath fading channels

吳萬雄, Ng, Man-hung. January 2001 (has links)
published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy
200

Design, adoption and implementation issues in RFID applications

Zeng, Yuyu, 曾玉玉 January 2006 (has links)
published_or_final_version / abstract / Industrial and Manufacturing Systems Engineering / Master / Master of Philosophy

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