Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 88 for “"VHF"”.
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Wideband rotary transformer for VHF use
… transformers has been applied to the design of a VHF rotary coupler that has a bandwidth ratio of 1000:1, and that requires no physical contact between the stator and rotor. A combination of balanced and unbalanced transmission line theory has been used to predict the performance of the coupler, …
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Refraction interference elimination employing smart arrays at VHF
Radio interference from the Middle East is one of the most significant problems plaguing the local radio services in Cyprus today. The issue is particularly noticeable on the highway, where it affects in-car tuners in all coastal areas of the island when the weather is hot and humid. In this work, …
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Range-doppler synthetic aperture radar processing at VHF frequencies
… the application of range-Doppler processing at VHF frequencies for wide azimuth beam, airborne, stripmap SAR systems with zero Doppler centroid and modest pulse bandwidths relative to the carrier frequency (simulations less than 30 percent). Such a system is the South African SAR (SASAR) VHF …
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VHF bipolar transistor power amplifiers: measurement, modeling, and design
… practicing engineers. A new design technique for VHF linear power amplifiers using bipolar junction transistors is presented in this report. This design technique is simple in its application but yields accurate results. The design technique is based upon a transistor model which is simple enough …
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A VHF/UHF Voltage Controlled Oscillator in 0.5um BiCMOS
The dramatic increase in market demand for wireless products has inspired a trend for new designs. These designs are smaller, less expensive, and consume less power. A natural result of this trend has been the push for components that are more highly integrated and take up less real estate on the …
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Design of Ultrawideband Digitizing Receivers for the VHF Low Band
… to digitize very large bandwidths in the VHF low band (30 to 100 MHz). However, methodology for designing such a receiver is not well established. The difficulties of this design are numerous. There are various man-made interferers occupying this spectrum which can block desired signals or …
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The re-engineering of VHF mobile radio services in the UK
… and considerations necessary for the design of VHF mobile radio systems, and is directed particularly at the requirements of the emergency services of the United Kingdom. It was occasioned by an international regulatory decision to re-allocate part of their existing operating frequencies. This …
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Man-made impulsive noise on the 137 MHz VHF LEOSAT channel
… implementation. A proposed LEOSAT link at VHF would provide paging and radio-location services to subscribers in automobiles. Link performance has traditionally been determined by thermal background noise produced internally as well as externally to the radio receiver. Most recently, …
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An Investigation of Fundamental Frequency Limitations for HF/VHF Power Conversion
… identify some of the solutions for HF/VHF power conversion and to provide guidelines and tools to optimize the performance of power converters by maximizing frequency. A number of multi-megahertz power converters are examined to evaluate the present status and future trend of HF/VHF …
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VHF and UHF radar observations of postsunset e-region turbulence with ALTAIR
U of I Only Restriction set for Item 119541 on 2021-10-08T16:28:20Z with date by astein@illinois.edu.
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Modelagem do canal de propagação em banda estreita na faixa de VHF alto
… para outras frequências incluindo a faixa do VHF alto, de modo que a cobertura de ambos os serviços não seja interrompida, pelo contrário, sejam mantidas ou até mesmo melhoradas. Neste trabalho, será apresentado um estudo sobre as medidas do sinal de televisão digital na cidade de Gama, que …
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Research and Development of Low-Profile, Small Footprint Antennas for VHF-UHF Range Applications
… but low-profile and small-footprint antennas for VHF-UHF range applications remains an ongoing work. VHF range spans approximately 54 - 88 MHz while UHF roughly ranges from 174 - 890 MHz. The inverse relationship between the physical length and resonant frequency of an antenna, which is a measure …
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Measuring Noise in the VHF Band and Its Effect on Low SNR Signal Detection
With the increasing demand for access to the crowded radio frequency spectrum, cognitive radios have been suggested as one solution. Cognitive radios would be frequency agile and able to sense their radio environment and opportunistically use empty spectrum. Spectrum sensing, monitoring a given …
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The use of field-effect transistors at hf and vhf as tuned amplifiers and mixers
Digitized by Kansas Correctional Industries
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The use of field-effect transistors at hf and vhf as tuned amplifiers and mixers
Digitized by Kansas Correctional Industries
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VHF Radar Studies of the Mid-Latitude E-Region Ionosphere From Camp Santiago, Puerto Rico
Regarding quasi-periodic layers detected above 100 km in Puerto Rico, our observations show that descending signatures can be explained as the consequence of descending plasma layers that are being dumped at lower E-region altitudes due to the action of gravity waves. Overall, a striking result is …
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Pseudo Doppler Direction Finding System for Localizing Non-Cooperative VHF Transmitters with a Hybrid UAS
… these systems rely on commercially available VHF receivers and are limited in transmission modulation techniques and frequency ranges. The majority of these systems are expensive which places them outside the reach of most individuals while the current open source designs require specialized …
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Untersuchungen zur Initiierung von paroxysmalen Vorhofflimmern mittels neuartiger Schrittmachertechnologie
Das Vorhofflimmern (VHF) stellt als die häufigste anhaltende Rhythmusstörung eine grosse Herausforderung in der Arrhythmieforschung dar. Induktionsmuster des VHF wurden bisher nur wenig untersucht. Im Rahmen der atrial-fibrillation-therapy-study wurden bei Patienten mit medikamentös …
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Design of miniaturized radio-frequency DC-DC power converters
… capable of operating efficiently into the VHF regime (30-300 MHz) and their integration into power electronic systems of high power density. A good integrated power MOSFET presages high-density converters. Previous VHF systems were demonstrated with bulky and expensive RF Lateral, …
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