x, 120 leaves : diags., tables ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.1978) from the Dept. of Electrical Engineering, University of Adelaide

116 leaves : diags., tables ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.1978) from the Dept. of Electrical Engineering, University of Adelaide

Thesis (M.Eng.Sc. 1979) from the Department of Electrical Engineering, University of Adelaide.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

published_or_final_version / abstract / toc / Electrical and Electronic Engineering / Master / Master of Philosophy

Thesis (MScEng)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: The aim of this thesis was to investigate the use of behavioral level models in receiver simulations using the capabilities of Agilent's Advanced Design System. Behavioral level modeling has become increasingly attractive because it offers faster and easier results for system level simulations. The work in this thesis focused strongly on nonlinear measurements to characterize the various nonlinear phenomena that are present in amplifiers and mixers. Measurement automation software was developed to automate the process. An error correction technique was also developed to increase the accuracy of spectrum analyzer measurements. The measured data was used to implement the behavioral level amplifier and mixer models in ADS. The accuracy of the models was compared to measured data and the different available models were compared. Finally the models were combined to realize different receivers and were used to do typical receiver tests. These test include gain and gain compression, two-tone intermodulation and spurious responses. The results are compared to measured data to test the accuracy and usefulness of the models and simulation techniques. / AFRIKAANSE OPSOMMING: Die doel van hierdie tesis was om stelsel-vlak gedrags-modelle te ondersoek soos hulle in Agilent se Advanced Design System (ADS) aangebied word. Die modellering van die stelselvlak-gedrag van komponente en stelsels is aantreklik aangesien dit 'n hoë vlak beskrywing van komplekse kommunikasie stelsels moontlik maak. Akkurate stelsel-vlak simulasies sal lei tot vinnige ontwikkeling en evaluasie van nuwe sisteme. Die resultate wat verkry word is egter afhanklik van die beskikbaarheid van akkurate stelsel-vlak gedragsmodelle Die tesis het baie sterk op metings staat gemaak om die nie-liniêre gedrag van versterkers en mengers te karakteriseer. Meet sagteware is ontwikkel om die verskillende metings te automatiseer. Fout korreksie vir spetrum-analiseerder-metings is ook ontwikkel. Die gemete data is gebruik om die nie-liniêre gedrags-modelle in ADS te implementer. Die modelle is in simulasies gebruik en die akuraatheid van die simulasies is teen gemete data getoets. Die finale deel van die tesis gebruik die modelle om tipiese ontvanger karakteristieke te voorspel. Die volgende toetse is gedoen: aanwins en kompressie, twee-toon intermodulasie en hoer orde meng produkte. Die resultate van die toetse is met gemete data vergelyk om die akuraatehied en bruikbaarheid van die verskillende modelle te vergelyk.

An extensive radio wave propagation measurement campaign was conducted at 1.3 GHz and 4.0 GHz inside four buildings, including a sports arena, a modern closed-plan office building, and two dissimilar, open-plan factories. Measurements were recorded at 57 locations using base station antenna heights of 1.7 meters and 4.0 meters. Results were obtained for mean and maximum excess delay, rms delay spread, time delay jitter, differential delay jitter, and path loss through analyses of impulse response estimates, which were obtained via repetitive 5 ns probing pulses. The effects of frequency, antenna height, topography (line-of-sight or obstructed direct path), and building environment on delay spread and path loss are quantified. Results indicate that, on average, the frequencies and antenna heights used in this study have minimal impact on rms delay spread and path loss. However, topography and building environment significantly affect these parameters. RMS delay spread values as high as 230 ns were observed in open plan factories. Computed path loss power law exponents are 1.84 and 2.35 for line-of-sight and obstructed topographies, respectively. A second campaign was conducted to determine the effects of antenna directivity and polarization on propagation parameters. On average, line-of-sight indoor channels offer 8 dB of cross-polarization discrimination, whereas obstructed environments offer less than 3 dB. Directional antennas provide a significant reduction in rms delay spread over omni-directional antennas. In line-of-sight environments, circular polarization provides an additional delay spread reduction. / Master of Science

The radio interface greatly affects performance of wireless communication systems. Hard-wired communication links use transmission lines to connect communication terminals. The propagation characteristics of radio frequency signals on these transmission lines are well known. In wireless communication systems, however, the transmission line with a known impulse response is replaced by a radio channel with an impulse response that is constantly changing as the users roam throughout the coverage area. The varying impulse response is due to the multiple path propagation of the signals from the transmitter to the receiver. The design of emerging small cellular (commonly known as microcellular) wireless systems is limited by the multipath propagation characteristics of the channel. Once these propagation conditions are understood, systems may be designed more efficiently in terms of cell layout, interference reduction, and system performance. This thesis presents a technique for automated propagation prediction in outdoor microcellular radio channels using ray tracing. The basic method is to integrate site-specific environmental data with a geometrical optics model to trace the propagation of energy from the transmitter to the receiver. Software written in C++ is used to automatically trace rays that are reflected, transmitted, scattered, or diffracted as they propagate through the channel. The automated software uses AutoCAD® to maintain the site-specific building data incorporated into the model. Details of the building database, propagation model, and software implementation are included in this thesis. The accuracy of the model and its software implementation is tested against wide band measurements taken on the Virginia Tech campus. Results, included here, indicate that the received signal can be accurately predicted in both line-of-sight and obstructed microcell topographies. / Master of Science

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.

Thesis (D.Sc.)--University of the Witwatersrand, Faculty of Science, 1959.