The purpose with the report is to show that it is possible to design a class-D amplifier, using a programmable FPGA mounted on a developing card from Xess and a H-bridge. The FPGA was programmed in VHDL which is the language the software from Xilinx use to implement a logical function into the FPGA The logical function corresponds to a modeling of the music signal and the modeling can be described as a comparator which compare the music signal with a triangle wave and as a out signal produce a pulse width modulated (PWM) signal. The report is also a review and evaluating of two different modulating technologies, AD- modeling and BD-modeling. A detailed part about how the H-bridge was designed and how it works. The result of this project is a working audio amplifier to a significant lower price than the products in todays market..

This report present the design and manufacturing of a wide-band driver amplifier placed in radar module for airborne applications. The major goals for the amplifier were a high efficiency and to deliver a predefined output power. To reach the second goal an additional preamplifier had to be constructed. The amplifiers were constructed in three steps: Design and Layout in the software Microwave Office, Mounting components and Verification. The driver amplifier was decided to be a push pull configuration consisting of two parallel transistors biased in class AB.

Softube has developed DSP-card and software for simulation of the sound of old tube amplifiers. The purpose with this thesis is to design a compact amplifier with high power to function together with the DSP-card and build a unit that can replace several other guitar amplifiers. The advantages with that kind of solution could be that it would be cheaper, easier to carry and easier to stor than the real amplifiers. The amplifier that has been designed is of class D type with digital PWM modulator. There is several types of amplifier modules on the market that use analog input signal, but if one of them would be used a D-A converter is needed on the DSP card.

This report is an outcome of a master degree project at Linköpings University in co-operation with Micronic Laser Systems AB. The purpose with this master degree project was to investigate how to implement a receiver in a data transfer system. The system consists of several data channels, where every channel consists of three parts: driver, transmission lines and receiver. The driver send low amplitude differential signals via the transmission lines to the receiver that amplifies and converts it to a single-ended signal. The receiver has to be fast and be able to feed an output signal with high voltage swing.

The purpose of this thesis is to investigate peoples experience when listening at audio books. During recent years the use of audio books has increased significantly. With that knowledge and the fact that this is an almost unexplored area within Library- and Information science our interest grew even stronger. The thesis is based on two different theories. To be able to place audio books in a context we have applied a media- consumption perspective by asking questions like when, where and how the media-consumption takes place.

The last few decades the development in the field of electronics has been huge. The components performance gets better at the same time as the manufacturing cost decreases. Many of the design moments that have to be done, are done automatically today, but it can get better. Especially for analog circuit design.At Electronic System in Linköpings universitet, research is in progress to develop a tool that can design analog circuits in reasonable time. It means that it has to size the components (transistors, resistances, capacitances etc), so that the circuit can fulfill the performance requirements.

This paper describes a method for wireless energy transfer via near-field electromagnetic inductionthat is inexpensive, simple and can be applied to almost any type of system, regardless of size andenergy demands.The method uses a primary unit consisting of an oscillator, amplifier and inductive coil thattransfers energy to a secondary unit consisting of a coil, rectifier and voltage regulator. Two typesof oscillators and several amplifier designs were realized and evaluated together with a multitudeof flat coils of both monofilar and bifilar type.The results show that it is important to use an oscillator whose frequency is dependent on theinductance of the connected transmission coil, such as the Colpitts oscillator. This is preferable toan oscillator with a preset frequency, such as a Schmitt-trigger oscillator..

The project deals with the evaluation and testing of speaker and microphone elements as well as microphone cavity.The first part of the report comprises a comprehensive theoretical part about drivers, microphone elements, and to some extent microphone cavity.The goal was to , on the behalf of the company Limes Audio AB, develop proposals on microphone element and cavity as well as drivers for a speakerphone application, based on specific factors. The main factors were performance, price and form factor.The aim was to create the best possible conditions for Limes Audio's software developers to implement the company's audio-enhancing software, mainly adaptive echo cancellation.The testing was carried out using Adobe Audition and MatLab. The test methods were developed in conjunction with Limes Audio and are described below.The project will result in suggestions for a speaker, a microphone and a cavity. The cavity were removed from the product because the results indicated that the cavity matter little for the end result.The report concludes with a discussion on how the measurements could have been enhanced to simplify the interpretation of the results and making the testing more efficient..

This project started when LIC Audio AB wanted help with development of a hearing aid for public rooms. The problem is that a lot of people suffer from some sort of hearing impairment. In places with a lot of people and background noise the problem becomes bigger and the sound seems to flow together. During the project we found the solution for the problem in the shape of a headphone. The headphone receives a signal from a preinstalled hearing loop.

This research analyzed differences in measurements of magnetic field strength and frequency response in five audio induction loops installed in rooms of wooden construction materials and five audio inductive loops installed in rooms of steel reinforced concrete constructions. The inductive loops were installed at floor level and the measurements were made at the listening height of 1.2m. Measurements of background noise, field strength and frequency response were made at fifteen different measurement points across the room. The research measurements showed that there are differences in field strength and frequency response between these two conditions, whether the audio induction loop is installed in a wooden construction or the audio induction loop is installed in a reinforced concrete construction. The results had a significance level of p=0,05..

This paper describes a method for wireless energy transfer via near-field electromagnetic inductionthat is inexpensive, simple and can be applied to almost any type of system, regardless of size andenergy demands.The method uses a primary unit consisting of an oscillator, amplifier and inductive coil thattransfers energy to a secondary unit consisting of a coil, rectifier and voltage regulator. Two typesof oscillators and several amplifier designs were realized and evaluated together with a multitudeof flat coils of both monofilar and bifilar type.The results show that it is important to use an oscillator whose frequency is dependent on theinductance of the connected transmission coil, such as the Colpitts oscillator. This is preferable toan oscillator with a preset frequency, such as a Schmitt-trigger oscillator..

Målet med det här arbetet har varit att utveckla en ljudmotor skriven i JavaScript som underlättar ljuddesign för webbsidor. Ett sekundärt mål har varit att diskutera hur relevant Flash är för ljuddesign på webben och huruvida HTML5 har möjligheten att ersätta Flash i framtiden. En ljudmotor som har fått namnet Klang har utvecklats som ett JavaScriptbibliotek för integration med interaktiva webbsidor. Ljudmotorn använder Web Audio API, den nyligen föreslådda ljudstandarden för HTML5, som bas för uppspelning och processering av ljud. För att anpassa ljuddesignen för olika typer av webbsidor har Klang möjligheten att dynamiskt styra hur musik och ljud spelas upp beroende på vilken typ av webbsida den används för och hur en besökare använder denna webbsida.

ILT Scandinavia har under 20 år distribuerat ett Tyskt högtalarfabrikat. För ca 2 år sedanlanserade de sin egen högtalarserie, BK Audio, på marknaden. De vill nu ta ytterligare ett stegoch lansera BK Audio på fler marknader.Examensarbetet går ut på att ta fram en ny högtalarserie som kan passa i hemmamiljöer, denfår gärna tilltala butiks- och restaurangägare också. För att genomföra projektet har teorier förprojekt- och designmetodik använts. Högtalarna ska vara trådlösa och ha utbytbara skal.Efter analyser av både BK Audio:s varumärke och deras närmsta konkurrenter inom trådlösahögtalarsystem samt ett antal enkäter till potentiella kunder skapades ett konceptförslag.Konceptförslaget utvärderades och anpassades enligt teorier för högtalarkonstruktion.Därefter presenterades ett mer genomarbetat konceptförslag, varpå en modell byggdes.Sammanfattningsvis har ett högtalarkoncept, bestående av en satellithögtalare och ensubwoofer skapats.

Många av dagens dator och TV-spelsljud är anpassade för högtalaruppspelning, i många fall även flerkanalssystem som 5.1 surround och liknande. Få spel är anpassade för uppspelning genom hörlurar och för att få en bra ljudlokalisering i hörlurar behövs ofta någon form av surroundhörlurar. Vi tror att man kan skapa trovärdig (Riktnings)återgivning av ljud i hörlurar genom bara två ljudkanaler genom så kallat binauralt ljud. Vi kommer i detta arbete att beskriva de faktorer som spelar roll i vår stereohörsel, varför de fungerar samt vilka svagheter som finns i detta system. Vi kommer att skapa ett system för att behandla realtidsgenererat binauralt ljud för spel och beskriva de verktyg vi valt och den generella arbetsprocessen.

A current conveyor is an active building block that can be used to implement most active and passive components. It differs from the operation amplifier in that it uses current instead of voltage. The current conveyor also has significantly higher voltage gain over a broader frequency range. To simplify the construction of analogue circuits and increase the construction efficiency it is desirable to use a top-down methodology. This means that the whole system is partitioned into a hierarchy of subsystems.