A video conferencing situation combines the acoustical properties of two rooms. As the talker is located in a one room, the sound reaching the listener in an other room will be colored by the acoustical characteristics of both of them. This thesis aims to survey the current conditions in a selection of video conferencing rooms, by investigating several room acoustic parameters involving background noise, re- verberation time, speech clarity and speech intelligibility. Convolution of recorded impulse responses enables the rooms to be combined, and the combined results to be evaluated. The evaluation of the results allow limit values for acceptable quality for video conferencing to be suggested. Limits for the highest acceptable values for the early decay time and the lowest acceptable values for speech clarity are sug- gested both for the single-room situation, and for the combination of rooms. The suggested values are based on specifications from building standards and relations between measured room acoustic descriptors.

The objective of this assignment was to implement a bistatic radio acoustic sounding system (RASS) in a anechoic chamber, using equipment at hand. The purpose of which was to enable measurements within a controlled environment to avoid variations in wind, humidity and temperature. Radio acoustic sounding systems as well as planning of the test setups have been theoretically investigated in previous work.The approach to the task has been to choose equipment assumed suitable for the experiment and verify the equipment suitability by measuring the technical characteristics relevant to the task. Then a bistatic RASS was constructed within a anechoic chamber. Using software defined radios, the received signals were digitally sampled. So was the acoustic field in the volume of interaction.Although processing the results failed to detect any sign of scatter, the equipment has been thoroughly tested. The acoustic, as well as electromagnetic equipment have shown good results with respect to the suitability for such a system prototype.No conclusion as to whether any scattering occurs as a consequence of the acoustic field can be made, as the absence of such indications may merely indicate insufficient sending power or too high levels of background noise. Prior to these findings, the equipment were concluded to be suitable for a prototype bistatic RASS. Methods to improve the measurement quality have been suggested as future work.

In this report various techniques used to estimate head related impulse responses are compared. The purpose is to investigate the effectiveness of presenting auralization via the QuietPro system's earplugs, and see if sound localization in the horizontal plane is possible. In addition, a theoretical study to relate pinna dimensions to features found in measured head related impulse responses is described. In the theoretical part, impulse responses for 33 left ears found in the CIPIC database were investigated, as an attempt to relate reflection coefficients and time delays associated with reflections from the pinna to physical dimensions of the ear. Unfortunately, no clear connection was found.In the listening test, the participants were sitting in the middle of a circle, surrounded by 36 numbered pieces of paper (either standing on top of e.g loudspeakers or attached to microphone stands) that indicated possible sound directions. 14 subjects performed sound localization tests by listening to three consecutive noise bursts of 150 ms duration with 100 ms silence between. Prior to the experiment, measurements of the subject's head were made and used for customization of the models. The task was to determine which of the 36 possible directions the sound was meant to come from. Seven simulation conditions were evaluated, each including 33 stimuli. Four test stimuli were also presented, resulting in a total of 235 noise bursts for each subject.The results show that the presented methods provide directionality to the stimuli, and that sound localization is possible. However, a significant reduction in localization performance compared to what could be expected for normal hearing conditions is observed. A high number of front/back confusion is reported, and even some instances of left/rigth confusion. Accuracy of the results was not predicted by model complexity, and in some cases it turned out that adding more features significantly degraded the performance.

DSRC er et system for enveis eller toveis trådløs kommunikasjon med kort til medium rekkevidde,som blant annet brukes til å automatisere innkreving av bompenger i de største byene i Norge.Systemet benytter en interrogator og en DSRC-brikke populært kalt bompengebrikke. DSRCbrikkenmodulerer inn en unik identifikasjon på signalet den får fra interrogatoren, som foreksempel kan brukes til å identifisere brukeren som passerer igjennom en bompengering.NORBIT er et firma lokalisert i Trondheim som utvikler og produserer DSRC-produkter, blandtannet til det norske AutoPASS-systemet. NORBIT produserer et stort antall DSRC-brikkerhvert år, derfor er det viktig å ta hensynet til produksjonenskostnader. DSRC-brikkene kangjøres rimeligere ved bruk av andre substrat og ved å integrere komponenter som en del avgeometrien til antennen. Aluminiumsoksid er et substrat på markedet som er rimeligere, har godegenskaper for høye frekvenser, og kan fungere like godt som det substratet som brukes i dagensproduksjon. Dette substratet har høyere dielektrisitetskonstant, som fører til at antennen ogtilhørende matenettverk må redesignes.Studiet har da omhandlet hvordan antennen til DSRC-brikken kan designes med aluminiumsoksidsubstrat og fortsatt fungere like godt som antennen til dagens DSRC-brikke. I simuleringene gikkbruken av aluminiumsoksid gikk på bekostning antenneforsterkningen, men det viste seg imidlertidmulig å kompensere for denne nedgangen ved å eksitere andre og litt utradisjonelle TM-moder iantennen. Dagens DSRC-brikker bruker ortogonale spalter for å oppnå sirkulær polarisasjon, mendet viste seg også mulig i simuleringene å bruke geometrien til selve antenneelementet for å oppnådet samme.Det ble utarbeidet to forslag til antennedesign, desverre viste det seg at det var stor forskjell mellomsimulering og målinger på fysiske antenner. Testantennene tilfredsstillte ikke kravene tilundertrykkelse av krysspolarisasjon og konversjons forsterkning til en DSRC-brikke. Det er ganskevanlig at det må flere revisjoner til for å få et optimalt antennedesign. Derfor er det også forslåttvidereføring og forbedringer av antennedesignet.

This report deals with the possibility of creating a LED light source, to be used withhyperspectral fluorescence imaging. There are commercially available light sources thatcould be used, but they are expensive, they do not necessarily emit the right wavelength, the uniformity of the field is questionable and they are difficult to modify.First a batch of Light emitting diodes were acquired, these were subjected to a seriesof tests to classify their limitations and determine which diodes were to be included in the final light source. A spectrometer was used to determine the emitted wavelength of each diode and which scenarios could change the wavelength of the emitted light. Aphotodiode was used to acquire the viewing angle of the LEDs and their relative radiantpower. Images gathered by a hyperspectral camera were used to determine the relevancyof noise produced by the current source. When the light emitting diodes were chosen,the photodiode was used to make an image of the light field. The final light source wasmounted on the hyperspectral camera to gather fluorescent images.The final tests revealed a fully functional light source with potential to be used on aregular basis, but the current source was too cumbersome and the field was not optimal.These are issues that can be dealt with and this light source can in the future provide a cheap and easily modifiable light source alternative.

SammendragDenne oppgaven ser på metoder for databasert prediksjon av spredningsfaktorer. Teorien bak dette har blitt presentert. Det har blitt utarbeidet en metode for å lage måleserier med impulsresponser langs en linje i et rom. Disse måleseriene har blitt lastet inn i Matlab. Her har det har blitt utarbeidet en metode for etterbehandling av disse, med den hensikt å hente ut hver enkelt bølgefront fra den samlede matrisen med alle impulsresponsene. Dette har gjort det mulig å studere hver enkelt bølgefront i detalj og sammenligne de med simulerte verdier. Feilkilder i forbindelse med målingene og etterbehandlingen har også blitt vurdert. Det pekes til slutt på en del videre arbeid som kan være aktuellt å gjøre i framtiden for å utvikle og studere metoden enda nærmere.

This research is entirely devoted to the study and fabrication of structures with periodic dielectric constants, also known as photonic crystals (PhCs). These structures show interesting dispersion characteristics which give them a range of prohibited frequencies that are not allowed to propagate within the crystal. This property makes them suited for a wide array of photonic-based components. One-dimensional photonic crystals are already commercialized and are of widespread use in for example thin-film optics, and two-dimensional PhCs are available in the form of photonic crystal fibers.Much work is being done on the analysis of photonic crystals and their application in various photonic components. In designing any photonic crystal component the properties of the crystal must first be understood and analyzed. By using frequency-domain simulation software we have studied the properties of bulk photonic crystals and designed the ideal structure for confining light of any design wavelength within a three-dimensional photonic crystal slab.Through simulations, the ideal periodicity of the PhC has been found along with its optimal geometry for waveguiding purposes. The study was then extended to three dimensions and the optimal thickness of the PhC slab was found. By using these determined values we were able to properly confine light inside a defect in a photonic crystal structure. This phenomenon allowed us to briefly examine the use of a photonic crystal as a waveguide. This research was then continued by attempting to fabricate such a device. Methods entailing how to create a silicon-on-insulator wafer through plasma enhanced chemical vapor deposition were developed. Profilometry, refractometry and ellipsometry were used to characterize the quality of the SOI wafer. A surface roughness between 1.5-3.5 nm was found. The losses of the amorphous silicon was attempted to be measured through ellipsometry, but the ellipsometer was found incapable for loss meassurements. Better testing methods must therefore be developed.The PhC waveguiding structure is formed thorugh electron-beam lithography, and various thicknesses of photoresist are tested and characterized. Furthermore, various materials were attempted as an etch mask. Polymethyl methacrylate, $SiO_2$, and chromium were all utilized, where only the latter showed good enough selectivity for silicon etching. This lead to using both chromium and $SiO_2$ as the mask of choice. Several etching methods were tested. Both standard wet etching, room-temperature reactive ion etching recipes as well as cryogenic inductively coupled plasma reactive ion etching recipes were employed. Dry etching was found to be of insufficient quality, while the complete isotropy of wet etching rendered it impractical for fine structures needed for a PhC waveguide.The final solution which allowed the formation of the photonic crystal was a stacked structure, using both chromium, oxide, and PMMA throughout the etching process in order to achieve the wanted results. The PMMA was used as an etch mask to imprint the pattern in the oxide layer. The oxide layer was in turn used as an etch mask to imprint the pattern into the chromium, and the chromium served as the final mask to be used during cryogenic silicon etching. The cryogenic silicon etching recipe was characterized and shown to be sufficiently anisotropic as well as having a rather high maximum etch depth. The recipe show an unwanted formation of so-called silicon grass, and a high sidewall roughness is observed. Finally, a complete PhC waveguiding structure with both a grating, a taper, and a silicon waveguide is fabricated. Although they require more work to be optimized, the methods presented in this thesis provide the basis for fabricating a multitude of optical components, not only PhC's.

Today's audio in video-conference rooms do not in general have high quality audio standards.Most of the set-ups are PC-Speakers mounted on the wall, with a microphone on the table. With this, strong room modes are often excited from the speakers. When speaking to someone which also have bad equipment, the speech-intelligibility can be really bad. One solution presented with this Master thesis is to improve the loudspeaker set-up by mounting a DML(Distributed Mode Loudspeaker) above and parallel to the conference table. The DML will then radiate sound on both sides of the table equally in opposite phase, like a dipole. This will also minimize sound-radiation to the ceiling and the office-table.The DML is designed and modified from a loudspeaker originally deigned by the loudspeaker-company e-Scape. The Plexiglas panel, made out of an Acrylic material, has exciters mounted on the panel. After testing different combinations of two and three exciters in an anechoic chamber, the polar frequency response of the DML with only one exciter had a much better response than the other combinations.The idea of mounting the DML over the table is that the audience will get closer to the sound source, and room-effects will be very small compared to the direct signal. This should give a much better speech-intelligibility of the perceived sound signal compared to existing solutions. Subjective tests show that the majority of the participants preferred the DML rather than the PC-Speaker in all areas; a more natural sound, more closeness to the one speaking and better speech-intelligibility.One problem, which is seen on the measurements and feedback from the participants on the subjective test, is a low SPL(Sound Pressure Level) in the low frequency area. Under 100Hz the magnitude of the DML is reduced, compared to the response of ordinary monopole speakers. From this frequency area one can also see some dipole effects from the results, which gives us good qualities such as less radiation to the ceiling and the office table.

I små rom, kan fenomenet resonans være årsak til ugunstige akustiske forholdved at visse frekvenser blir overdrevent kraftige mens andre toner blir knapthørbare. Spesielt gjelder dette rom tiltenkt akustisk bruk, som opptaksstudioerog kontrollrom. Problemet kan unngås ved akustisk behandling i ettertid og/ellerarkitektonisk planlegging, og begge deler kan dra nytte av datasimulering. Tilgjengeligesimuleringsverktøy er konsentrert på mellom- og høyfrekvensområdet, ogdekker ikke lavfrekvente bølgers diffraktive oppførsel. Akselerasjon av parallelleberegninger på GPU tillater derimot hurtig og presis simulering, med metodeneFDTD og FDFD. En programvare beskrives og delvis utvikles i C#. Den drarnytte av GPU-en gjennom Cudafy via CUDA. Den vil forventes å kunne assistereved plassering av høyttaler, lyttepunkt og bassabsorbenter, såvel som i geometriskutforming av et rom.I denne oppgaven betraktes resonansproblemet først fra et erfaringsperspektiv,liknende situasjoner og mangelen på reelle løsninger identifiseres, og dette dannerbakgrunnen for arbeidet. Videre behandles fenomenet resonans teoretisk, i enkletermer og med flere eksempler. Dette etterfølges av en matematisk-teoretiskgjennomgang av simuleringsmetodene FDTD og FDFD. Til slutt beskrivesimplementasjonsdetaljer og utarbeidede løsninger, samt de uløste utfordringene– især FDFD-implementasjon – som gjenstår før programmet kan bli en realitet.

Effektforsterkere er kritiske komponenter i dagens trådløse kommunikasjonssystemer, og må derfor tilfredsstille mange krav. De siste årene har metoder for å øke effektiviteten til forsterkere, samt design rundt gallium nitrid-transistorer (GaN), fått mye oppmerksomhet. Som følge av dette har det i denne oppgaven blitt sett nærmere på prinsippene bak klasse F og invers klasse F effektforsterkere. Videre har to effektforsterkere, med senterfrekvens ved 2 GHz, blitt designet og realisert rundt en 6 W GaN-transistor fra Cree ved hjelp av simulert load-pull.Designet av forsterkerne ble gjort i Advanced Design System, her ble det brukt en storsignalmodell for transistoren, levert av Cree. Load-pull-simuleringer ble utført for å finne optimale laster for transistoren, og forsterkernes utgangsmatchenettverk ble designet på bakgrunn av disse lastene. Forsterkerne ble realisert på bakgrunn av designene og små- og storsignalmålinger, og målinger med modulert signal ble utført på de realiserte forsterkerne. Målingene viste at det var relativt god korrelasjon mellom disse og simuleringsresultatene. Småsignalmålingene viste at begge forsterkerne hadde lavere S$_{11}$ enn -12 dB over en båndbredde på 0,8 GHz, og at den ene forsterkeren hadde relativt god forsterkning over det samme båndet. Måleresultatene viser at forsterkerne har henholdsvis 8,40 dB og 9,58 dB forsterking, 39,93 dBm og 39,23 dBm utgangseffekt og 58,90 % og 57,76 % power added efficiency ved 1 dB kompresjon. På det meste hadde forsterkerne henholdsvis 40,56 dBm og 40,43 dBm utgangseffekt, dette tilsvarer over 11 W. Videre viste målingene med modulert signal at forsterkerne hadde mindre enn 0,5$^circ$ fasekompresjon for 16 QAM-signaler med 11 dBm gjennomsnittseffekt.Resultatene oppnådd i denne oppgaven viser at forsterkerdesign basert på GaN-teknologi har potensial til å oppnå god effektivitet, samt høy utgangseffekt og/eller stor båndbredde. Resultatene viser også at det er mulig å oppnå gode forsterkerdesign basert på en god storsignalmodell og simulert load-pull.