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FQPSK VERSUS PCM/FM FOR AERONAUTICAL TELEMETRY APPLICATIONS; SPECTRAL OCCUPANCY AND BIT ERROR PROBABILITY COMPARISONSLaw, Eugene, Feher, Kamilo 10 1900 (has links)
International Telemetering Conference Proceedings / October 27-30, 1997 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The aeronautical telemetry community is investigating alternative modulation methods to the commonly used non-return-to-zero (NRZ) pulse code modulation (PCM)/frequency modulation (FM). This paper outlines the important characteristics being investigated. Measured data comparing the spectral occupancy and bit error probability (BEP) performance of PCM/FM with that of a prototype constant envelope Feher’s quadrature phase shift keying (FQPSK) modulator and demodulator will also be presented. Measured results in several radio frequency bands demonstrate that the 99.99% and -60 dBc bandwidths of filtered FQPSK are only approximately one-half of the corresponding bandwidths of optimized PCM/FM even when the signal is non-linearly amplified. The signal energy per bit to noise power spectral density (E /N ) required for a BEP of 1×10 b 0 -5 for non-optimized FQPSK was approximately 12 dB which is approximately the same as limiter discriminator detected PCM/FM.
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Selection process of auto-ID technology in warehouse management : a Delphi studyHassan, Mayadah January 2014 (has links)
In a supply chain, a warehouse is a crucial component for linking all chain parties. Automatic identification and data capture (auto-ID) technology, e.g. RFID and barcodes are among the essential technologies in the 21st century knowledge-based economy. Selecting an auto-ID technology is a long term investment and it contributes to improving operational efficiency, achieving cost savings and creating opportunities for higher revenues. The interest in auto-ID research for warehouse management is rather stagnant and relatively small in comparison to other research domains such as transport, logistics and supply chain. However, although there are some previous studies that explored factors for the auto-ID selection decision in a warehouse environment, those factors (e.g., operational factors) have been examined separately and researchers have paid no attention to all key factors that may potentially affect this decision. In fact, yet there is no comprehensive framework in the literature that comprehensively investigates the critical factors influencing the auto-ID selection decision and how the factors should be combined to produce a successful auto-ID selection process in warehouse management. Therefore, the main aim of this research is to investigate empirically the auto-ID technology-selection process and to determine the key factors that influence decision makers when selecting auto-ID technology in the warehouse environment. This research is preceded by a comprehensive and systematic review of the relevant literature to identify the set of factors that may affect the technology selection decision. The Technology-Organisation-Environment (TOE) framework has been used as lens to categorise the identified factors (Tornatzky & Fleischer, 1990). Data were collected by conducting first a modified (mixed-method) two-round Delphi study with a worldwide panel of experts (107) including academics, industry practitioners and consultants in auto-ID technologies. The results of the Delphi study were then verified via follow-up interviews, both face-to-face and telephone, carried out with 19 experts across the world. This research in nature is positivist, exploratory/descriptive, deductive/inductive and quantitative/qualitative. The quantitative data were analysed using the statistical package for social sciences, SPSS V.18, while the qualitative data of the Delphi study and the interviews were analysed manually using quantitative content analysis approach and thematic content analysis approach respectively. The findings of this research are reported on the motivations/reasons of warehouses in seeking to use auto-ID technologies, the challenges in making an auto-ID decision, the recommendations to address the challenges, the key steps that should be followed in making auto-ID selection decision, the key factors and their relative importance that influence auto-ID selection decision in a warehouse. The results of the Delphi study show that the six major factors affecting the auto-ID selection decision in warehouse management are: organisational, operational, structural, resources, external environmental and technological factors (in decreasing order of importance). In addition, 54 key sub-factors have been identified from the list of each of the major factors and ranked in decreasing order of the importance mean scores. However, the importance of these factors depends on the objectives and strategic motivations of warehouse; size of warehouse; type of business; nature of business environment; sectors; market types; products and countries. Based on the Delphi study and the interviews findings, a comprehensive multi-stage framework for auto-ID technology selection process has been developed. This research indicates that the selection process is complex and needs support and closer collaboration from all participants involved in the process such as the IT team, top management, warehouse manager, functional managers, experts, stockholders and vendors. Moreover, warehouse managers should have this process for collaboration before adopting the technology in order to reduce the high risks involved and achieve successful implementation. This research makes several contributions for both academic and practitioners with auto-ID selection in a warehouse environment. Academically, it provides a holistic multi-stage framework that explains the critical issues within the decision making process of auto-ID technology in warehouse management. Moreover, it contributes to the body of auto-ID and warehouse management literature by synthesising the literature on key dimensions of auto-ID (RFID/barcode) selection decision in the warehouse field. This research also provides a theoretical basis upon which future research on auto-ID selection and implementation can be built. Practically, the findings provide valuable insights for warehouse managers and executives associated with auto-ID selection and advance their understanding of the issues involved in the technology selection process that need to be considered.
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THE USE OF TELEMETRY IN AN ELECTROMAGNETIC TEST ENVIRONMENTPapich, William J. 10 1900 (has links)
International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The U.S. Army Redstone Technical Test Center (RTTC) uses telemetry as a vital part of
its data acquisition and analysis for electromagnetic environmental effects developmental
testing of U.S. Army weapon systems. Testing in an electromagnetic environment poses
several unique challenges. These challenges have resulted in the development of highly
customized telemetry and data acquisition systems. This paper discusses the design and
integration of past and current telemetry needs to incorporate real-time or near real-time
simulations or scene generations into the testing process.
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RADIO FREQUENCY OVERVIEW OF THE HIGH EXPLOSIVE RADIO TELEMETRY PROJECTBracht, Roger, Dimsdle, Jeff, Rich, Dave, Smith, Frank 10 1900 (has links)
International Telemetering Conference Proceedings / October 26-29, 1998 / Town & Country Resort Hotel and Convention Center, San Diego, California / High explosive radio telemetry (HERT) is a project that is being developed jointly by Los
Alamos National Laboratory and AlliedSignal FM&T. The ultimate goal is to develop a
small, modular telemetry system capable of high-speed detection of explosive events,
with an accuracy on the order of 10 nanoseconds. The reliable telemetry of this data,
from a high-speed missile trajectory, is a very challenging opportunity. All captured data
must be transmitted in less than 20 microseconds of time duration. This requires a high
bits/Hertz microwave telemetry modulation code to insure transmission of the data within
the limited time interval available.
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The measurement of radio frequency complex permeability of thin round wiresStuart, Thomas (Thomas Edward Walter) 04 1900 (has links)
Thesis (PhD)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: This thesis is concerned with the measurement of the complex permeability of
thin round wires at radio frequencies. This is of interest as such wires are used
in various applications, such as absorbing chaff. Iron and nickel alloys are also
used for their good tensile properties but have an undesired electromagnetic effect
which needs to be characterised. Although little work has been done in this field
in recent decades it remains a relevant problem. In this thesis the advantages of
accurate wide-band measurements performed by automatic network analysers are
applied to the field.
The measurement system is a closed coaxial transmission line with a short
circuit termination. The centre conductor is the wire of interest. The surface
impedance of the wire is related to complex permeability and is measured using
low-loss transmission line approximations applied to half-wavelength resonances.
The loss associated with complex permeability is separated from conductivity by
a D.C. conductivity measurement.
A full wave analysis of the coaxial mode was performed and compared to
measured values. The maximum error of the propagation constant was found to
be 31% at the highest frequencies and was primarily due to length uncertainties.
By varying parameters expected error bands around the measured permeability
were found. These bands are of the order 1 and demonstrate that the system is
sufficiently robust.
The measurement of the permeability of two non-magnetic wires was performed
and a relative permeability of 1 was found, demonstrating the correct
working of the system. A steel wire was measured and compared to measurements
found in literature. The permeability dropped as frequency rose as was expected,
and an acceptable comparison to other measurements was made as there
is no verification standard.
Thus a simple measurement system that takes advantage of calibrated automatic
network analyser measurements has been developed and demonstrated to
work with sufficient accuracy. / AFRIKAANSE OPSOMMING: In hierdie tesis word die meting van die komplekse permeabiliteit van dun
ronde drade by radio frekwensies ondersoek. Hierdie drade word in verskeie
toepassings gebruik, waaronder dié van absorberende materiale. Nikkel- en ysterallooie
word ook vir hul goeie breekkrageienskappe gebruik. In laasgenoemde
gevalle moet die ongewenste elektromagnetiese effekte wat voorkom, gekarakteriseer
word. Hoewel baie min werk in onlangse dekades gedoen is, bly die meting
van die komplekse permeabiliteit 'n relevante probleem. In hierdie tesis word
die voordele van akkurate wyeband metings, soos geneem deur 'n outomatiese
netwerk analiseerder, toegepas in dié veld.
Die meetopstelling is 'n geslote koaksiale transmissielyn, kortgesluit aan een
end. Die middel geleier is die draad van belang. Die oppervlak impedansie van
die draad is verwant aan die komplekse permeabiliteit, en word gemeet deur die
gebruik van lae verlies transmissielyn benaderings, soos toegepas op halfgolf resonante
frekwensies. Die verlies wat met die komplekse permeabiliteit geassosieer
word, word van die geleidingsvermoë onderskei deur 'n G.S. meting van die geleidingsvermoë.
'n Volgolf analise van die koaksiale mode is uitgevoer en met gemete waardes
vergelyk. 'n Maksimum fout van 31% by die hoogste frekwensie is in die voortplantingskonstante
gevind. Hierdie volg primêr uit onsekerhede in lengte. Deur
die parameters te varieer kon 'n verwagte foutband rondom die gemete permeabiliteit
gevind word. Hierdie bande is van die orde 1 waaruit volg dat die stelsel
'n genoegsame robuustheid toon.
Die komplekse permeabiliteit van twee nie-magnetiese drade is gemeet en 'n
relatiewe permeabiliteit van 1 is gevind. Hierdie bevestig die korrekte werking van
die stelsel. 'n Staal draad is opgemeet en met gepubliseerde meetresultate vergelyk.
Soos verwag, verminder die permeabiliteit met 'n verhoging in frekwensie.
Hoewel geen verifiëringstandaard beskikbaar is nie, is 'n aanvaarbare vergelyking
met ander metings gemaak.
Die produk van die navorsing is 'n metingstelsel wat, met behulp van 'n gekalibreerde
outomatiese netwerk analiseerder, aanvaarbare akkuraatheid in die meting
van die komplekse permeabiliteit van dun ronde drade by radio frekwensies kan
verkry.
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Pulse power device characterization for amplifier designFourie, Paul 12 1900 (has links)
Thesis (MSCIng)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: Bi-polar Si transistors optimized for pulse conditions is still the most popular choice as
amplification element in the final stages of solid-state radar amplifiers in L and S band. With the
radar market being small, the design data for these devices is normally fairly limited and it is up to
the designers to thoroughly characterize them for their designs. This is normally done through loadpull
experiments. Professional automated load-pull equipment is very expensive especially at the
higher power levels. In spite of being automated and under computer control, load-pull exercises
still is very time consuming and as such expensive. For small companies that only occasionally need
to design such amplifiers it is not economically viable to acquire such equipment and different
strategies have to be found to stay competitive.
This report investigates such a strategy and its implementation.
A procedure to quickly and accurately characterize such devices was developed and two amplifiers
were designed and build with this procedure and compared to their traditional counterparts for
verification. The results were very promising and with a bit more work, the technique can likely be
used to characterize these devices for design work outside of the parameters designated by the
manufacturers. / AFRIKAANSE OPSOMMING: Bipolere Silikon transistors wat vir werking onder gepulsde toestande geoptimiseer is, is nog steeds
die mees gewilde keuse as versterkingselement in die finale stadiums van vastetoestand radar
versterkers in die L en S bande. Met die radar mark wat geredelik klein is, is die ontwerp inligting vir
hierdie elemente gewoonlik redelik karig en is dit die taak van die ontwerpers om die elemente te
karakteriseer vir hulle ontwerp doeleindes. Dit word normaalweg gedoen deur lastrek eksperimente.
Geoutomatiseerde lastrek toerusting is baie duur, veral as dit onder hoë drywingstoestande moet
werk. Al is die toerusting geoutomatiseer en onder rekenaar beheer, is lastrek oefeninge nog steeds
baie tydrowend en daarom dan ook baie duur. Vir klein maatskappye wat net nou en dan nodig het
om sulke versterkers te ontwerp is dit gewoon nie ekonomies regverdigbaar om sulke toerusting aan
te skaf nie, en ander strategië moet gevind word om ekonomies kompeterend te bly.
Hierdie verslag ondersoek so 'n strategie en die implimentering daarvan.
n Prosedure om gepulsde bipolere transistore vinnig en akkuraat te karakteriseer is ontwikkel en
twee versterkers is met die prosedure ontwerp en gebou. Die versterkers is geverifieer deur hulle
met hulle tradisionele eweknië te vergelyk. Die resultate lyk baie belowend en met n bietjie meer
werk kan die metode waarskynlik ook gebruik word om die transistors buite die toepassings gebied,
soos deur die vervaardigers aangedui, te gebruik.
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Modular approach to the development of a two-way radio receiver systemKellerman, Valpre Cecilia 12 1900 (has links)
Thesis (MScIng)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: The preliminary development of a FM radio receiver module is discussed. An existing narrowband
system operating between 48MHz and 50MHz will be replaced. Digital components were
investigated, compared and used with analogue techniques to build a more flexible two-way radio
receiver system. A direct digital synthesizer was considered as a replacement for the current
synthesized phased lock loop local oscillator and much attention was given to the local oscillator
and mixer design, characteristics and measurement procedures.
A detailed study of receiver systems was undertaken to determine the specifications needed for
every receiver component to achieve satisfactory receiver performance in the end. Receiver
characteristics as well as receiver measurement procedures are defined. A software tool was
developed to aid the design process, establishing computationally whether the receiver
specifications are met prior to the final design.
The complete design process, from fundamental specifications through to the developed final
receiver module is discussed. A modular design approach was used to guarantee easy
manufacturing, substitution and testing. This approach comprises the break-down of the receiver
into well defined components that are each matched to 50O. The separate components of the
system were designed, measured and characterized to make it possible to replace only a single
component instead of the entire system when a part becomes redundant. / AFRIKAANSE OPSOMMING: Die grondslag vir die ontwikkeling van ‘n FM radio ontvanger module word in hierdie dokument
gelê. ‘n Bestaande noubandstelsel wat tussen 48MHz and 50MHz ontvang word vervang deur
hierdie nuwe stelsel wat aangewend sal kan word in die bestaande tweerigtingradio se omhulsel.
Digitale komponente is ondersoek, vergelyk en gebruik saam met analoogtegnieke om ‘n meer
buigsame radiostelsel te bewerkstellig. ‘n Direkte digitale sintitiseerder is oorweeg as ‘n
vervanging vir die huidige fasesluitlus ossillator met heelwat klem op die oscillator-en
mengerontwerp, komponent spesifikasies en metingsprosedures.
‘n Diepgaande studie van ontvangerstelsels is gedoen om te bepaal wat die tipiese spesifikasies
vir elke ontvangerstadium is, sodat die finale ontvanger se spesifikasies behaal kan word.
Ontvanger eienskappe en meetprosedures word volledig gedefinieer. ‘n Sagtewareprogram is
ontwikkel om die ontvanger-ontwerpsproses te vergemaklik deur vooraf te kan vasstel watter
ontvangerspesifikasies bereik sal kan word al dan nie.
Die volledige ontwerpsproses, vanaf fundamentele spesifikasies tot by die finale ontvanger word
omskryf. ‘n Modulere-ontwerp prosedure is gebruik ter versekering van die maklike vervaardiging,
vervanging en toetsing van elke komponent. Die radio is tydens ontwerp opgebreek in
boublokkies wat elkeen aangepas word na 50O. Elke aparte boublokkie van die ontvangerstelsel
is afsonderlik ontwerp, gemeet en volledig gespesifiseer om dit moontlik te maak om slegs een
komponent te vervang in plaas van die hele stelsel wanneer ‘n enkele komponent nie meer
beskikbaar is nie.
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The experimental design and characterisation of Doherty power amplifiersBrand, Konrad Frederik 12 1900 (has links)
Thesis (MScEng (Electrical and Electronic Engineering))--University of Stellenbosch, 2006. / Modern day digital modulation techniques in communication systems produce large peak-to-average
ratios. To maintain linearity, power amplifiers have to operate at backed-off levels. This results in low
efficiency with consequences such as high power consumption, short battery life and excessive heat
in power amplifiers. A Doherty amplifier is an efficiency enhancement technique which increases an
amplifier’s efficiency at backed-off levels.
This thesis presents a design procedure for a Classical Doherty amplifier. A method where Sparameter
measurements from a transistor are used to predict the transistor’s transmission phase
response for varying input power is presented. This method is found to be accurate by comparing it
to measurements done on a non-linear network analyser. The measured S-parameters are also
used to design the Doherty amplifier at its predicted peak output power.
Two Classical Doherty amplifiers are designed, manufactured and characterised. The
measurements are performed on a custom measurement setup using in-house developed Matlab
code to automate the measurements. The first Doherty amplifier used small-signal Siemens CFY30
GaAs FETs and the second Doherty amplifier used 10W Motorola MRF282 LDMOS transistors. The
performance of both amplifiers is compared to similar balanced amplifiers and shows improvements
in their efficiency.
The improvement in efficiency for the 10W Doherty power amplifier in relation to a balanced amplifier
is compared to results found in the literature and a good correspondence between the measured
and published results were obtained.
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Benefits to processor load for quadrature baseband versus radio frequency demodulation algorithmsNdovi, Lusungu 12 1900 (has links)
Thesis (MScEng (Electrical and Electronic Engineering))--Stellenbosch University, 2008. / The continued advancement and improvement of software-defined radio technology has
been a key factor in furthering research into the implementation of most signal
processing algorithms at baseband. Traditionally, these algorithms have been carried
out at RF, but with the coming of SDR, there has been a need to shift the processing
down to baseband frequencies which are more compatible with the fast developing
software radio technology.
The study looks at selected demodulation algorithms and investigates the
possibility and benefits of carrying them out at QBB. The study ventures into the area
of beamforming, multipath compensation, Doppler shift compensation and matched
filter detection. The analysis is carried out using Matlab simulations at RF and QBB.
The results obtained are compared, not only to evaluate the possibility but also the
benefits in terms of the processing load. The results of the study showed that indeed,
carrying out the selected demodulation algorithms at QBB was not only possible, but
also resulted in an improvement in the processing speed brought about by the reduction
in the processing load.
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Photonic microwave processor based on fiber optical parametric amplifierLi, Jia, 李佳 January 2009 (has links)
published_or_final_version / Electrical and Electronic Engineering / Master / Master of Philosophy
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