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7433 Uppsatser om Signal theory - Sida 3 av 496

Detektering av in- och utandning vil bilkörning med hjälp av Matlab

Volvo Human Monitoring (VHM) is an ongoing project at Volvo Cars where they measure, amongst other parameters, inhalation and exhalation through a device called Respiratory Inductance Plethysmograph (RIP), on drivers. RIP measures changes in the cross-sectional area of the chest and abdomen. When the driver is in motion, such as when she is turning the vehicle, the cross-sectional area changes and noise in the RIP signal may arise.The noise results in a large number of manual adjustments in the analysis of the RIP signal, which is very time consuming and the validity of the device for measuring inhalation and exhalation is questioned.The purpose of this study was to improve the efficiency of the analysis of the RIP signal. The goal was to create a new data processing tool in Matlab that automatically detects inhalation and exhalation from a RIP signal with higher validity compared to the previous data processing tool.In this study, nine tests were performed on drivers while they were driving in different scenarios such as highway, country road and in city traffic. Inhalation and exhalation was measured using a RIP, a pneumotachograph with a tightly sealed facemask and a thermocouple placed between the nose and mouth, which was used as reference to the RIP.The result of this study was a data processing tool that automatically detects inhalation and exhalation with higher validity compared to the previous data processing tool.

Karakterisering av bioslam för modellering av biogasproduktion

The report aims to investigate how well a certain type of affordable embedded single board computer can hold up against today's more expensive computers in a computer system by doing various tests on a system with the specified requirements. The system has a Raspberry Pi as the single board computer which task is to control a camera based on coordinates obtained from a server as well as capture and stream a video signal on a network.The researches were conducted to check how much network traffic a single-chip computer sent in different video formats and how much CPU utilization was required. Studies were also made to ensure the accuracy of the camera control. The researches have been experimental, where several tests have been performed and analyzed.The results show that a sufficiently good accuracy can be obtained from the camera steering unit, in which two different servos have been investigated. When the video format MJPEG and H.264 are used, the single-chip computer is able to transmit a video signal up to 1280x720 at 15 fps.

Trådlös överföring av mätsignaler

Målet med examensarbetet var att ett trådlöst mätdatainsamlingssystem ska tas fram för att ersätta det trådburna insamlingssystem som idag används vid FOI i Bromma, vid mätning på vindtunnelmodeller. Projektet innefattar konstruktion, inköp, dokumentation, test och utvärdering. En del i projektet är att utvärdera ett nytt CAD system för kretskortskonstruktion.Enligt framtagen kravspecifikation konstrueras ett signalkonditionerande kort som förstärker, balanserar och filtrerar insamlad signal samt ett processorkort som digitaliserar och skickar konditionerad signal trådlöst till mottagande del.Prototypen som projektet resulterar i, uppfyller de krav och specifikationer som FOI hade på det nya systemet, dvs. analog signalkonditionering, digitalisering och tvåvägskommunikation. Systemet har med sin enkla funktion påvisat att lösningen är realiserbar och att den fungerar.

Styrning av portabelt luftfilter

Målet med detta examensarbete var att utveckla en fungerande prototyp för styrning av ett portabelt filter med varvtalsreglering och tidräkning. Om möjlighet fanns, skulle även tillval som tryckstyrning, gasindikering och flödesmätning göras. Dessa tillval kunde regleras med hjälp av fyra knappar. För att allt skulle vara lättare att hålla under uppsikt, kunde alla inställningar och värden ses på en LCD-display. Konstruktionen består av en mikrokontrollerstyrd elektronikkoppling med extern realtidsklocka för drifttidsräkning.

System för avlyssning, modifiering och överföring av analoga signaler

I detta examensarbete har ett system utvecklats som samplar och digitaliserar en högfrekvent analog signal och lagrar de samplade värdena i ett minne. Systemet genererar en analog utsignal genom att antingen direkt omvandla de samplade värdena eller genom att använda sampels lagrade i minnet som källa för omvandlingen. Det går då att använda systemet både som en passiv länk eller som en signalkälla.En triggfunktion har implementerats för att på ett effektivt sätt ge möjlighet att fylla minnet med för användaren intressanta delar av en signal. Arbetet går även ut på att undersöka om ett FPGA-kort av typen Stratix II DSP Development Kit är ett lämpligt utvecklingskort för att ta fram en prototyp av systemet. Kortet har undersökts med avseende på olika begränsningar för det utvecklade systemet, till exempel vilka frekvenser en insignal kan samplas i.Ett annat användningsområdet för systemet är möjligheten att få alla sampels lagrade på kortet presenterat i en textfil på en ansluten PC.

Kan en periodiseringsbaserad investeringsstrategi effektiviseras med hjälp av fundamental analys?

This paper investigates whether the traditional accrual based trading strategy first documented by Sloan (1996) can be refined using fundamental analysis. Specifically, this is done by implementing the composite signal F_SCORE introduced by Piotroski (2000) to identify financially strong or weak firms. We find that by applying both investment models simultaneously, in a model we call P_KOMB, the mean market-adjusted return earned by an investor exploiting the accrual anomaly can be increased by 14.8% annually. This is achieved by taking a long position in strong firms (as defined by the composite signal) in the lowest accrual portfolio, while an offsetting short position is taken in weak firms in the highest accrual portfolio, repeated annually between 1997 and 2007. Consistent with prior studies, positive market-adjusted returns can be attained through assessment of accruals as well as key value drivers found in historical financial data.

Design av slutsteg med digital PWM-teknik för gitarr

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.

Studie utav ett larmsystem ur ett signalteoretiskt perspektiv : Study of a detector by a signal detection theory

In present-day situation many libraries use detectors so that they can be able to prevent attempts too take out books without registering them. The university library in Jonkoping is one of the libraries that have such a detector. But unfortunately it doesn?t always work correct and can also react on other things a part from books. This is a big problem since the library staff don?t have time to check all signals that comes from detector.

Prestanda och precision pa? en enkortsdator i ett system med realtidskrav

The report aims to investigate how well a certain type of affordable embedded single board computer can hold up against today's more expensive computers in a computer system by doing various tests on a system with the specified requirements. The system has a Raspberry Pi as the single board computer which task is to control a camera based on coordinates obtained from a server as well as capture and stream a video signal on a network.The researches were conducted to check how much network traffic a single-chip computer sent in different video formats and how much CPU utilization was required. Studies were also made to ensure the accuracy of the camera control. The researches have been experimental, where several tests have been performed and analyzed.The results show that a sufficiently good accuracy can be obtained from the camera steering unit, in which two different servos have been investigated. When the video format MJPEG and H.264 are used, the single-chip computer is able to transmit a video signal up to 1280x720 at 15 fps.

Sammanvägning av diversitetssignaler med FPGA

Genom samtal med radioamatörer visade det sig att det fanns ett intresse för att använda rumsdiversitet på deras mottagare då de upplevde fädning (vid körning med bil) som ett problem för hörbarheten. I ett system där mottagaren är stationär och sändaren mobil kommer den mottagna signalen att fäda ibland då radiovågorna tar olika vägar till mottagaren och ibland förstärker och ibland stör varandra. Tanken med detta examensarbete var att kunna ta emot två bandbegränsade audiosignaler från två mottagare med varsin antenn som tar emot samma signal (rumsdiversitet) och vikta ihop dessa med lämplig metod för att få ut en bättre signal. Om man kunde implementera ett diversitetssystem med VHDL i en FPGA så skulle man få ett system som var både billigt och flexibelt. I det här examensarbetet har jag försökt att konstruera ett sådant system..

En indirekt metod för adaptiv reglering av en helikopter

When a helicopter is flying, the dynamics vary depending on, for example, speed and position. Hence, a time-invariant linear model cannot describe its properties under all flight conditions. It is therefore desirable to update the linear helicopter model continuously during the flight. In this thesis, two different recursive estimation methods are presented, LMS (Least Mean Square) and adaptation with a Kalman filter. The main purpose of the system estimation is to get a model which can be used for feedback control.

Går det att mäta blodtryck med fotopletysmografi och bioakustisk sensor i kombination?

The aim of the work was to investigate the possibility to combine information from PPG and bio-acoustic technology to extract information that is related to the blood pressure. The measurements have been carried out with several different configurations. First the relation between arterial sounds and the PPG-signal was studied. After those measurements with both PPG and the bio- acoustic technique was concluded on people in different positions and after riding a bike. The goal was to vary the blood pressure.

Optimering av ultraljudssändare- och mottagare avseende räckvidd, strålningsvinkel och energiförbrukning

Embedded Systems Lab at Umeå University is currently part of a research project with the purpose to examine the behavior of dairy cows inside a barn. Each cow needs to be tracked with a precision of 50 cm, and since GPS-technique has poor functionality at indoor environments, an indoor positioning system needs to be developed.Embedded Systems Lab has already developed an indoor positioning system using IR-light and radio, but since this system demands extensive infrastructure and is rather expensive, an alternate positioning system using ultrasonic pulses and radio is being examined.In this report the range, beam angle and current consumption of ultrasonic transmitters- and receivers are investigated. Three different driver stages for the transmitter is tested, and two amplifier solutions for the receiver. The report also describes how the length of the transmitted ultrasonic pulse affects the received signal, accessibility of a ?shadowed? signal, and the effect of different sound frequency..

Aktiv bullerdämpning i ventilationssystem

Active headsets have been on the market for years and now it is time for something else to enter the stage. The technology of active noise reduction can for exmple also be used in ventilation systems for reducing ventilation noise. An active control system principally consists of four important components, namely the downstream error microphone, the upstream detection or reference microphone, the digital signal processor (DSP) and a loudspeaker. The upstream reference microphone listen to the primary ventilation noise and sends it to the DSP which makes a phase shift to the signal and sends it to the loudspeaker. The loudspeaker sends out the opposite waveform of the incoming one and reduce the primary ventilation noise.

Public Hear Aid

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.

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