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  • 1.
    Abrahamsson, Björn
    Linköping University, Department of Electrical Engineering.
    Architectures for Multiplication in Galois Rings2004Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    This thesis investigates architectures for multiplying elements in Galois rings of the size 4^m, where m is an integer.

    The main question is whether known architectures for multiplying in Galois fields can be used for Galois rings also, with small modifications, and the answer to that question is that they can.

    Different representations for elements in Galois rings are also explored, and the performance of multipliers for the different representations is investigated.

  • 2.
    Abrahamsson, Per
    Linköping University, Department of Electrical Engineering.
    Combined Platform for Boost Guidance and Attitude Control for Sounding Rockets2004Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    This report handles the preliminary design of a control system that includes both attitude control and boost control functionality for sounding rockets. This is done to reduce the weight and volume for the control system.

    A sounding rocket is a small rocket compared to a satellite launcher. It is used to launch payloads into suborbital trajectories. The payload consists of scientific experiments, for example micro-gravity experiments and astronomic observations. The boost guidance system controls the sounding rocket during the launch phase. This is done to minimize the impact dispersion. The attitude control system controls the payload during the experiment phase.

    The system that is developed in this report is based on the DS19 boost guidance system from Saab Ericsson Space AB. The new system is designed by extending DS19 with software and hardware. The new system is therefore named DS19+. Hardware wise a study of the mechanical and electrical interfaces and also of the system budgets for gas, mass and power for the system are done to determine the feasibility for the combined system.

    Further a preliminary design of the control software is done. The design has been implemented as pseudo code in MATLAB for testing and simulations. A simulation model for the sounding rocket andits surroundings during the experiment phase has also been designed and implemented in MATLAB. The tests and simulations that have been performed show that the code is suitable for implementation in the real system.

  • 3.
    Adolfson, Magnus
    Linköping University, Department of Electrical Engineering.
    Simulation of Emission Related Faults on a Diesel Engine2002Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    Today's legislation on exhaust gas emissions for heavy duty diesel (HDD) vehicles is more stringent than ever and will be even more tough in the future. More over, in a few years HDD vehicles have to be equipped with OBD (On-Board Diagnostics). This place very high demands on the manufacturers to develop better engines and strategies for OBD. As an aid in the process models can be used.

    This thesis presents extensions of an existing diesel engine model in Matlab/Simulink to be able to simulate emissions during standardized european test cycles. Faults in the sensor and actuator signals are implemented into the model to find out if there is an increase or decrease in the emissions. This is used to create a fault tree where it can be seen why predefined emission thresholds are exceeded. The tree is an aid when developing OBD.

    The results from the simulations showed that almost no faults made the emissions cross the thresholds. The only interesting faults were faults in the ambient temperature sensor and the injection angle actuator. This means that the OBD-system only needs to monitor a few components which implies a smaller system and less work.

  • 4.
    Adolfsson, Klas
    Linköping University, Department of Electrical Engineering.
    TCP performance in an EGPRS system2003Independent thesis Advanced level (degree of Magister), 20 points / 30 hpStudent thesis
    Abstract [en]

    The most widely used protocol for providing reliable service and congestion control in the Internet is the Transmission Control Protocol (TCP). When the Internet is moving towards more use in mobile applications it is getting more important to know how TCP works for this purpose.

    One of the technologies used for mobile Internet is the Enhanced General Packet Radio Service (EGPRS) extension to the popular GSM system. This thesis presents a low-level analysis of TCP performance in an EGPRS system and an overview of existing TCP, GSM and EGPRS technologies.

    The bottleneck in an EGPRS system is the wireless link – the connection between the mobile phone and the GSM base station. The data transfer over the wireless link is mainly managed by the complex RLC/MAC protocol.

    In this thesis, simulations were made to identify some problems with running TCP and RLC/MAC together. The simulations were made using existing EGPRS testing software together with a new TCP module. The simulation software is also briefly described in the thesis.

    Additionaly, some suggestions are given in order to enhance performance, both by changing the EGPRS system and by modifying the TCP algorithms and parameters.

  • 5.
    Afsarinejad, Arash
    Linköping University, Department of Electrical Engineering.
    Synkronisering med SyncML2002Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    The last couple of years the use of mobile devices such as mobile phones and PDAs has increased tremendously. Most of the these devices have their own protocols for synchronising data and this has given rise to a need for a standard synchronisation protocol, SyncML. This thesis compares this protocol against the existing ones. The comparison shows that the preferred choice is SyncML.

    Also an application using SyncML has been developed. The application's task is to synchronise the calendar on a mobile phone with a database on a computer.

  • 6.
    Ahlberg, Jörgen
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology.
    Active Contours in Three Dimensions1996Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    To find a shape in an image, a technique called snakes or active contours can be used. An active contour is a curve that moves towards the sought-for shape in a way controlled by internal forces - such as rigidity and elasticity - and an image force. The image force should attract the contour to certain features, such as edges, in the image. This is done by creating an attractor image, which defines how strongly each point in the image should attract the contour.

    In this thesis the extension to contours (surfaces) in three dimensional images is studied. Methods of representation of the contour and computation of the internal forces are treated.

    Also, a new way of creating the attractor image, using the orientation tensor to detect planar structure in 3D images, is studied. The new method is not generally superior to those already existing, but still has its uses in specific applications.

    During the project, it turned out that the main problem of active contours in 3D images was instability due to strong internal forces overriding the influence of the attractor image. The problem was solved satisfactory by projecting the elasticity force on the contour’s tangent plane, which was approximated efficiently using sphere-fitting.

  • 7.
    Ahlin, Karl
    Linköping University, Department of Electrical Engineering.
    Quality of Service i IP-nätverk2003Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    The original promise behind the Internet Protocol was to deliver data from a sender to the receiver using a best-effort approach. This means that the protocol makes no guarantees except that it will try to deliver the data to the destination. If some problem occurs the packet may be discarded by the network without any notice. No guarantees are made regarding the time it takes to deliver the data, the rate at which data will be delivered or if data is delivered in the same order it was sent. The best-effort approach is arguably the reason behind the success of the Internet Protocol and is what makes IP scalable to networks the size of the Internet. However, this approach is also a problem for network operators who want to offer better quality of service to some of their customers. This master thesis will discuss some of the theories behind the implementation of quality of service schemes in an IP network and also provide an example of how to implement it in an existing network.

  • 8.
    Ahlström, Linus
    Linköping University, Department of Electrical Engineering.
    Algoritmer för objektdetektering i SAR och IR-bilder2003Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    The first part of the thesis consists of a brief introduction to the general principles of target detection and the sensor-systems used. In the following part there is a theoretical description of the algorithms this thesis focuses on. The detection algorithms described in this paper are called Cell Average, Ordered Statistics, 2parameter and Gammadetector. Two different discriminators called Extended Fractal Features and Quadratic Gamma Discriminator are also described. The algorithms are tested on three different types of data, simulated SAR-pictures, authentic SAR-targets and IR-pictures. The last part account for the results, both those achieved with pictures and those results achieved when doing statistical tests, in this case MonteCarlo- simulations and Reciever Operating Characteristics-curves. The results show that the Gamma- detector and the QGD-algorithm perform best on the tests done in this thesis.

  • 9.
    Alfredsson, Jon
    Linköping University, Department of Electrical Engineering.
    Design of a parallel A/D converter system on PCB: For high-speed sampling and timing error correction2002Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    The goals for most of today’s receiver system are sampling at high-speed, with high resolution and with as few errors as possible. This master thesis describes the design of a high-speed sampling system with"state-of-the-art"components available on the market. The system is designed with a parallel Analog-to-digital converter (ADC) architecture, also called time interleaving. It aims to increase the sampling speed of the system. The system described in this report uses four 12-bits ADCs in parallel. Each ADC can sample at 125 MHz and the total sampling speed will then theoretically become 500 Ms/s. The system has been implemented and manufactured on a printed circuit board (PCB). Up to four boards can be connected in parallel to get 2 Gs/s theoretically.

    In an approach to increase the systems performance even further, a timing error estimation algorithm will be used on the sampled data. This algorithm estimates the timing errors that occur when sampling with non-uniform time interval between samples. After the estimations, the sampling clocks can be adjusted to correct the errors.

    This thesis is concerning some ADC theory, system design and PCB implementation. It also describes how to test and measure the system’s performance. No measurement results are presented in this thesis because measurements will be done after this project. The last part of the thesis discusses future improvementsto achieve even higher performance.

  • 10.
    Andersson, Anders
    et al.
    Linköping University, Department of Electrical Engineering.
    Hallgren, Daniel
    Linköping University, Department of Electrical Engineering.
    Passive Aircraft Altimetry using GPS as a Bistatic Radar: A simulation model2003Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    A common way to measure height in aerial vehicles is to use a radar height altimeter (RHM). Since the RHM transmits radar pulses that can be detected, a passive alternative would be desirable in military applications. The idea to use reflected signals from the Global Positioning System (GPS) as a bistatic radar, has been established over the last years. The GPS signals are already present and would not reveal aeroplanes in covert operations.

    In this thesis, the use of reflected GPS signals as a bistatic, passive altimeter is examined. A simulation model has been developed and implemented, and simulations using the model have been done. Different types of ground cover have been investigated, both water and land types, with varying reflectivity and scattering behaviour. For larger terrain variations, e.g. mountains and valleys, a ground elevation database has been used. Furthermore, several parameters, like the antenna coverage and the satellite elevation angle, have been varied and the result of this examined.

    The results of these simulations show that measuring height is possible for bothsea and land surfaces. The accuracy depends on several error factors, like a bias originating from surface roughness and measurement errors due to noise in the receiver. The simulations also show that the most important design parameter is the antenna, which must be designed to give a sufficiently large SNR, capture the specular reflection and avoid unwanted reflections.

  • 11.
    Andersson, David
    et al.
    Linköping University, Department of Electrical Engineering.
    Fjellström, Johan
    Linköping University, Department of Electrical Engineering.
    Vehicle Positioning with Map Matching Using Integration of a Dead Reckoning System and GPS2004Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    To make driving easier and safer, modern vehicles are equipped with driver support systems. Some of these systems, for example navigation or curvature warning systems, need the global position of the vehicle. To determine this position, the Global Positioning System (GPS) or a Dead Reckoning (DR) system can be used. However, these systems have often certain drawbacks. For example, DR systems suffer from error growth with time and GPS signal masking can occur. By integrating the DR position and the GPS position, the complementary characteristics of these two systems can be used advantageously.

    In this thesis, low cost in-vehicle sensors (gyroscope and speedometer) are used to perform DR and the GPS receiver used has a low update frequency. The two systems are integrated with an extended Kalman filter in order to estimate a position. The evaluation of the implemented positioning algorithmshows that the system is able to give an estimated position in the horizontal plane with a relatively high update frequency and with the accuracy of the GPS receiver used. Furthermore, it is shown that the system can handle GPS signal masking for a period of time.

    In order to increase the performance of a positioning system, map matching can be added. The idea with map matching is to compare the estimated trajectory of a vehicle with roads stored in a map data base, and the best match is chosen as the position of the vehicle. In this thesis, a simple off-line map matching algorithm is implemented and added to the positioning system. The evaluation shows that the algorithm is able to distinguish roads with different direction of travel from each other and handle off-road driving.

  • 12.
    Andersson, Helena
    Linköping University, Department of Electrical Engineering.
    Genus och informationsteknologi2004Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    This thesis discusses how the education in the Master of Engineering program can change to become more into line for the students needs, especially for the women, both directly in the education situation and later in their occupational roles. This is done using a gender perspective. Both the education and the occupation today is characterised by masculine norms and values. The education lacks gender perspective and is created by men, for men. The thesis gives concrete proposals on how to change two existing courses to better fit the students. Some of the most important changes are to make the goals of the courses more accessible and visible for the students, make sure that both men and women occurs in teaching positions and have course literature written by women as well as men.

  • 13.
    Andersson, Johan
    Linköping University, Department of Electrical Engineering.
    Rekommendationer för införande av public key infrastructure2002Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    The use of insecure networks -such as the Internet- to send and receive information has made the need for preventing unauthorised people reading it yet more important. One of the easiest way to do this is through public key cryptography. However, the problem with this solution is how to tie a specific public key to a certain subject. This is solved by letting a trusted third party issue a certificate that holds, as a minimum, the name of the subject and the subject's public key along with the issuer's digital signature on the information. The rules we make for issuing, revoking and verifying of certificates and the entities that are being used to do so are called PKI - Public Key Infrastructure. In this thesis we shall se what PKI really is in a more detailed way and which entities it constitutes of. We will also investigate some of the areas in which we could make use of it, for instance secure e-mail and virtual private networks. Next, we will look into some of the drawbacks with PKI and what you should think of in order to aviod these. Finally, we'll give recommendations for the implementation itself. As for the theory of cryptography, the basics is presented to the interested reader in a separate appendix.

  • 14.
    Andersson, Magnus
    et al.
    Linköping University, Department of Electrical Engineering.
    Severinson, Kristofer
    Linköping University, Department of Electrical Engineering.
    Hydroakustisk kommunikation med bandspridningsteknik2004Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    This thesis investigates techniques for stealth hydroacoustic communication using spread spectrum. The Swedish naval defense organisations have a vision that all their units should be able to communicate with each other, even between underwater vehicles. But the properties of water makes it a complex channel to use for wireless communications. Radiomagnetic waves have very limited range in water, therefore acoustic waves are used.

    In this report the basics of wireless communication systems are described including source coding, channel coding, modulation techniques as well as different techniques for spread spectrum. The fundamental principle for all spread spectrum systems is to use more bandwidth than necessary to spread the signal energy in the frequency spectrum. This limits the data rate but results in a robust communication link which is difficult to detect, intercept and to jam.

    In addition to the theoretical background, this thesis also gives a brief description of a Matlab system and a VHDL-system that was developed during the project. Finally the results of this project are presented and some suggestions of further developments are given.

  • 15.
    Andersson, Martin
    Linköping University, Department of Electrical Engineering.
    Konstruktion av förstärkare och insamplingssteg till en PSAADC i 0.25 um CMOS2002Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    The aim and goal of this work has been to design and implement a voltage reference network for a 12-bit PSAADC, Parallell Successive Analog to Digital Converter. A chip containing the design has been sent away for fabrication. Because of the long processing time, no measurement data are presented. The main specifications for the voltage reference generator is to generate stable reference voltages with low noise and a good PSRR. Efforts has also been made to minimize the power consumption.

  • 16.
    Andersson, Mikael
    et al.
    Linköping University, Department of Electrical Engineering.
    Karlström, Per
    Linköping University, Department of Electrical Engineering.
    Parallel JPEG Processing with a Hardware Accelerated DSP Processor2004Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    This thesis describes the design of fast JPEG processing accelerators for a DSP processor.

    Certain computation tasks are moved from the DSP processor to hardware accelerators. The accelerators are slave co processing machines and are controlled via a new instruction set. The clock cycle and power consumption is reduced by utilizing the custom built hardware. The hardware can perform the tasks in fewer clock cycles and several tasks can run in parallel. This will reduce the total number of clock cycles needed.

    First a decoder and an encoder were implemented in DSP assembler. The cycle consumption of the parts was measured and from this the hardware/software partitioning was done. Behavioral models of the accelerators were then written in C++ and the assembly code was modified to work with the new hardware. Finally, the accelerators were implemented using Verilog.

    Extension of the accelerator instructions was given following a custom design flow.

  • 17.
    Andersson, Peter
    Linköping University, Department of Electrical Engineering.
    Överföring av digital video via FireWire2002Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    Transmission of digital signals is today more frequently used than transmission of analog signals. One reason for this is that a digital signal is less sensitive to noise than an analog, another reason is that almost all signals today are handled in a digital format. This thesis describes the development of a system that receives digital video signals through FireWire. The standard for FireWire, which is a high performance serial bus, is under development. Today the standard of the bus supports transmission of data with a speed of up to 400 Mbit/s. In the future FireWire is supposed to transmit data with a speed of up to 3,2 Gbit/s. The thesis gives an introduction to the technique for FireWire and how it is implemented. It also includes a short description of digital video signals in DVCAM format.

  • 18.
    Andersson, Richard
    Linköping University, Department of Electrical Engineering.
    Evaluation of the Security of Components in Distributed Information Systems2003Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    This thesis suggests a security evaluation framework for distributed information systems, responsible for generating a system modelling technique and an evaluation method. The framework is flexible and divides the problem space into smaller, more accomplishable subtasks with the means to focus on specific problems, aspects or system scopes. The information system is modelled by dividing it into increasingly smaller parts, evaluate the separate parts and then build up the system “bottom up” by combining the components. Evaluated components are stored as reusable instances in a component library. The evaluation method is focusing on technological components and is based on the Security Functional Requirements (SFR) of the Common Criteria. The method consists of the following steps: (1) define several security values with different aspects, to get variable evaluations (2) change and establish the set of SFR to fit the thesis, (3) interpret evaluated security functions, and possibly translate them to CIA or PDR, (4) map characteristics from system components to SFR and (5) combine evaluated components into an evaluated subsystem. An ontology is used to, in a versatile and dynamic way, structure the taxonomy and relations of the system components, the security functions, the security values and the risk handling. It is also a step towards defining a common terminology for IT security.

  • 19.
    Andersson, Thord
    et al.
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology.
    Karlsson, Mikael
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology.
    Neuronnätsbaserad identifiering av processparametrar vid tillverkning av pappersmassa1997Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Artificiella neurala nätverk (ANN) är en teknik som under de senaste tio åren har mognat och som numera återfinns i allt fler tillämpningar så som avläsning av skriven text, linjär programmering, reglerteknik, expertsystem, taligenkänning och många olika sorters klassificeringsproblem [Zurada, 1992]. Vi ville i vårt examensarbete försöka använda ANN i en industriell process där standardmetoder ej fungerat tillfredsställande eller varit svåra att tillämpa. En sådan process fann vi i tillverkningen av pappersmassa.

    För att tillverka pappersmassa från ved krävs en lång och komplicerad process uppdelad i flera olika steg. Ett av dessa steg är den så kallade kokningen där man med hjälp av högt tryck och varm lut bryter ned träflis till fibrer. Kokningsprocessen är komplex, pågår under lång tid (ca. 8 timmar) samt påverkas av en stor mängd parametrar och därför krävs det stor erfarenhet och kunskap för att kunna styra den. På Kværner Pulping Technologies i Karlstad, som konstruerar bl.a. kokare, har man tagit fram en simulator för kokningsprocessen för att man skall få en bättre insikt i hur processen fungerar och följaktligen kunna styra kokningen på ett bättre sätt. Simulatorns beteende är beroende av ett antal s.k. dolda parametrar som är en delmängd av de parametrar som antas påverka kokningsprocessen. Dessa dolda parametrar är svåra/omöjliga att mäta och därför sätts dessa i simuleringen till estimerade värden. De, i den riktiga processen, motsvarande dolda parametrarna varierar dock på ett okänt sätt. De påverkas dels av interna processer i kokaren, dels av externa orsaker, t.ex. kan träflis av en annan kvalitet matas in i kokaren. Detta leder till simulatorn ger bra simuleringar under ganska kort tid då de dolda parametrarna är approximativt konstanta.

    Om man på något sätt skulle kunna detektera förändringarna i de dolda parametrarna i processen och föra över dessa till simulatorn, skulle den kunna gå "parallellt" med kokprocessen. Simulatorn skulle i detta fall utgöra ett utmärkt kompletterande verktyg för den person som styr kokprocessen, eftersom han/hon skulle få en bättre uppfattning om vad som händer/hände i processen och därmed få ett större beslutsunderlag för styrning. Detta förutsätter att simulatorn är så pass bra att den under stationära förhållanden i parametrarna lyckas fånga den globala utvecklingen i kokaren med tillräcklig precision.

    Som ett första steg för att nå detta mål avser vi i denna rapport att undersöka om detektering av förändringar i de dolda parametrarna i simulatorn är möjlig med hjälp av framåtkopplade ANN och inlärningsalgoritmen resilient propagation.

    Rapporten är uppdelad i 7 kapitel där vi i kapitel 2 kommer behandla problemet mer i detalj. Kapitel 3 och 4 är av allmänt slag där vi beskriver tillverkningsprocessen för papper och vad artificiella neurala nätverk egentligen är. I kapitel 5 beskriver vi de olika lösningsförslag som behandlats och de resultat vi har uppnått. Slutsatser och resultat sammanfattas i kapitel 6 . Det finns mycket mer vi skulle vilja pröva på och undersöka, dessa fortsatta arbeten beskriver vi kapitel 7. Sist i rapporten kommer bilagorna 1 och 2 med detaljer som vi finner relevanta, men som är för skrymmande att ta med i huvuddelen av rapporten. I bilaga 3 har vi bifogat den programkod vi producerat under arbetets gång.

  • 20.
    Andréasson, Thomas
    Linköping University, Department of Electrical Engineering.
    Signal Processing Using Wavelets in a Ground Penetrating Radar System2003Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    This master's thesis explores whether time-frequency techniques can be utilized in a ground penetrating radar system. The system studied is the HUMUS system which has been developed at FOI, and which is used for the detection and classification of buried land mines.

    The objective of this master's thesis is twofold. First of all it is supposed to give a theoretical introduction to the wavelet transform and wavelet packets, and also to introduce general time-frequency transformations. Secondly, the thesis presents and implements an adaptive method, which is used to perform the task of a feature extractor.

    The wavelet theory presented in this thesis gives a first introduction to the concept of time-frequency transformations. The wavelet transform and wavelet packets are studied in detail. The most important goal of this introduction is to define the theoretical background needed for the second objective of the thesis. However, some additional concepts will also be introduced, since they were deemed necessary to include in an introduction to wavelets.

    To illustrate the possibilities of wavelet techniques in the existing HUMUS system, one specific application has been chosen. The application chosen is feature extraction. The method for feature extraction described in this thesis uses wavelet packets to transform theoriginal radar signal into a form where the features of the signal are better revealed. One of the algorithms strengths is its ability to adapt itself to the kind of input radar signals expected. The algorithm will pick the "best" wavelet packet from a large number of possible wavelet packets.

    The method we use in this thesis emanates from a previously publicized dissertation. The method proposed in that dissertation has been modified to the specific environment of the HUMUS system. It has also been implemented in MATLAB, and tested using data obtained by the HUMUS system. The results are promising; even"weak"objects can be revealed using the method.

  • 21.
    Andrén, Magnus
    Linköping University, Department of Electrical Engineering.
    MPEG-4-Compatible Set-Top Box for IP-networks Based on Open Standards: A Systems Study2003Independent thesis Basic level (professional degree)Student thesis
    Abstract [sv]

    The purpose of this thesis is to examine the possibilities of creating a MPEG-4-compatible set-top box for IP-networks based on open standards.

    Existing alternatives for transporting MPEG-4 over IP are evaluated and ISMA is found to be an important actor within the area. ISMA is a non-profit corporation formed to provide a forum for the creation of specifications that define an interoperable implementation for streaming rich media over IP-networks.

    Two different designs based on ISMA's recommendation are constructed and evaluated. The designs have different levels of complexity and the more complex design is found to be better due to its extended functionality.

    During the design process a number of problems related to this kind of set-top box are discovered. It is believed, however, that many of these problems will be solved within the near future.

  • 22.
    Anstensen, Jan
    Linköping University, Department of Electrical Engineering.
    An investigation of the possibility of defining a new conditional access application programming interface for digital television receivers2002Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    Digital television broadcasters use conditional access (CA) systems to protect some of their services from being viewed by people not subscribing for these services. A manufacturer of digital television receivers develops applications to handle the CA systems that the receiver shall support. A problem for the application developer is that a CA application developed for one specific CA system is usually not reusable for other CA systems because of the differences between CA systems. The CA systems are different in both their application programming interfaces (API) as well as the types of functionality that they support.

    This master thesis presents a study of three APIs from different CA systems. The possibilities of defining a new CA API that supports all the functionality that is provided by existing CA APIs while still being as similar as possible to these existing APIs are investigated. The conclusion from the study is that it is not possible to define this new CA API because the studied CA systems are so different and only small parts of the provided functionality are shared between them.

  • 23.
    Antelius, Henrik
    Linköping University, Department of Electrical Engineering.
    Retargeting a C Compiler for a DSP Processor2004Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    The purpose of this thesis is to retarget a C compiler for a DSP processor.

    Developing a new compiler from scratch is a major task. Instead, modifying an existing compiler so that it generates code for another target is a common way to develop compilers for new processors.

    This is called retargeting. This thesis describes how this was done with the LCC C compiler for the Motorola DSP56002 processor.

  • 24.
    Antonsson, Daniel
    Linköping University, Department of Electrical Engineering.
    A server application for Traffic Information Service: Broadcast2003Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    The need for increased safety and efficiency in civil aviation is pushing the introduction of Automatic Dependent Surveillance - Broadcast (ADS-B). The basic principle of ADS-B is that each aircraft is able to communicate its position and status over a radio data link to surrounding aircraft. In this way each aircraft obtains a detailed picture of the surrounding traffic. During a period of transition from today's radar surveillance to ADS-B many aircraft will not be equipped with the new data link technology and will therefore be invisible to the ADS-B equipped aircraft. The Traffic Information Service - Broadcast (TIS-B) has been conceived to be the solution to this problem. TIS-B is defined as a broadcast surveillance service in which data from the ordinary ground radar system is transmitted from a ground station to airborne systems, providing an air situation picture of the non-ADS-B stations.

    The topics of this thesis are the definition and implementation of a TIS-B server. The presented solution is an evaluation TIS-B server that will receive data from a data-fusing tracker and provide one or several TIS-B ground stations with data filtered according to the settings of the server.

  • 25.
    Arnsby, Mattias
    et al.
    Linköping University, Department of Electrical Engineering.
    Tägtström, Bo
    Linköping University, Department of Electrical Engineering.
    Modellering och reglering av drivenheter i gaffeltruck2003Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    To enable the enhancement of the driver's environment in a forklift, an alternative form of steering has been evaluated. An earlier concept with a combined driving and steering wheel has been exchanged to a concept with two driving wheels. A link wheel has replaced the combined driving and steering wheel. The steering is done through differentiation of the velocities of the two driving wheels.

    The scope of this master thesis is to create a simulation model, create a control program and to evaluate the concept of two driving wheels.

    The simulation model was created in Matlab/Simulink with the aid of enclosed functions written in C. The model is constructed so that the same control program can be used in the model as well as in the physical forklift prototype, which the model is based on. Validation of the simulation model shows that the model is in accordance with reality in a satisfactory manner.

    The control program is a compromise between a gentle behaviour of the forklift and a quick response to the driver's steering commands.

    Evaluation of the concept shows that steering through differentiation of the wheel velocities is possible although there are some deficiencies. The two main deficiencies are that, when driving slowly, the link wheel will affect the steering of the forklift in a negative manner, and that there are limitations regarding motor power.

  • 26.
    Arvidson, Martin
    et al.
    Linköping University, Department of Electrical Engineering.
    Carlbark, Markus
    Linköping University, Department of Electrical Engineering.
    Intrusion Detection Systems: Technologies, Weaknesses and Trends2003Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    Traditionally, firewalls and access control have been the most important components used in order to secure servers, hosts and computer networks. Today, intrusion detection systems (IDSs) are gaining attention and the usage of these systems is increasing. This thesis covers commercial IDSs and the future direction of these systems. A model and taxonomy for IDSs and the technologies behind intrusion detection is presented.

    Today, many problems exist that cripple the usage of intrusion detection systems. The decreasing confidence in the alerts generated by IDSs is directly related to serious problems like false positives. By studying IDS technologies and analyzing interviews conducted with security departments at Swedish banks, this thesis identifies the major problems within IDSs today. The identified problems, together with recent IDS research reports published at the RAID 2002 symposium, are used to recommend the future direction of commercial intrusion detection systems.

  • 27.
    Asplund, Fredrik
    Linköping University, Department of Electrical Engineering.
    Parsing of X.509 certificates in a WAP environment2002Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    This master thesis consists of three parts. The first part contains a summary of what is needed to understand a X.509 parser that I have created, a discussion concerning the technical problems I encountered during the programming of this parser and a discussion concerning the final version of the parser. The second part concerns a comparison I made between the X.509 parser I created and a X.509 parser created"automatically"by a compiler. I tested static memory, allocation of memory during runtime and utilization of the CPU for both my parser (MP) and the parser that had a basic structure constructed by a compiler (OAP). I discuss changes in the parsers involved to make the comparison fair to OAP, the results from the tests and when circumstances such as time and non-standard content in the project make one way of constructing a X.509 parser better than the other way. The last part concerns a WTLS parser (a simpler kind of X.509 parser), which I created.

  • 28.
    Axehill, Daniel
    et al.
    Linköping University, Department of Electrical Engineering.
    Sjöberg, Johan
    Linköping University, Department of Electrical Engineering.
    Adaptive Cruise Control for Heavy Vehicles: Hybrid Control and MPC2003Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    An Adaptive Cruise Controller (ACC) is an extension of an ordinary cruise controller. In addition to maintaining a desired set velocity, an ACC can also maintain a desired time gap to the vehicle ahead. For this end, both the engine andthe brakes are controlled.

    The purpose with this thesis has been to develop control strategies for an ACC used in heavy vehicles. The focus of the work has been the methods used for switching between the use of engine and brake. Two different methods have been studied, a hybrid controller and an MPC-controller.

    For the hybrid controller, the main contribution has been to use the influence of the surroundings on the acceleration of the truck. This consists of several parts such as wind drag, road slope and rolling resistance. The estimated influence of the surroundings is used as a switch point between the use of engine and brakes. Ideally, these switch points give bumpless actuator switches.

    The interest in the MPC-controller as an alternative solution was to achieve automatic actuator switching, thus with no explicitly defined switch points. The MPC-controller is based on a model of the system including bounds on the control signals. Using this knowledge, the MPC-controller will choose the correct actuator for the current driving situation.

    Results from simulations show that both methods solve the actuator switch problem. The advantages with the hybrid controller are that it is implementable in a truck with the hardware used today and that it is relatively simple to parameterise. A drawback is that explicit switch points between the uses of the different actuators have to be included. The advantages with the MPC-controller are that no explicit switch points have to be introduced and that constraints and time delays on signals in the system can be handled in a simple way. Among the drawbacks, it can be mentioned that the variant of MPC, used in this thesis, is too complex to implement in the control system currently used in trucks. One further important drawback is that MPC demands a mathematical model of the system.

  • 29.
    Axelsson, Andreas
    et al.
    Linköping University, Department of Electrical Engineering.
    Björhäll, Erik
    Linköping University, Department of Electrical Engineering.
    Real Time Speech Driven Face Animation2003Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    The goal of this project is to implement a system to analyse an audio signal containing speech, and produce a classifcation of lip shape categories (visemes) in order to synchronize the lips of a computer generated face with the speech.

    The thesis describes the work to derive a method that maps speech to lip move- ments, on an animated face model, in real time. The method is implemented in C++ on the PC/Windows platform. The program reads speech from pre-recorded audio files and continuously performs spectral analysis of the speech. Neural networks are used to classify the speech into a sequence of phonemes, and the corresponding visemes are shown on the screen.

    Some time delay between input speech and the visualization could not be avoided, but the overall visual impression is that sound and animation are synchronized.

  • 30.
    Axelsson, Mikael
    Linköping University, Department of Electrical Engineering.
    Modellbygge av mekaniksystem och riktmotorer i stridsvagn 1222002Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    This master thesis is one part of a project, called “StabSim”, with the purpose to develop a simulation model for the align and stabilisation system in main battle tank 122. The origin of this project is that it should be possible to make control analysis without risking any hardware. Besides that it will be easy to change components in order to investigate the behaviour of the system.

    The report includes modelling of tower and weapon mechanics and also the modelling of the synchronous motors, which control these. There is also a discussion whether the model can be reduced in order to receive a less stiff system.

    To get a proper system the models needs many parameters. Some of them are unknown and that’s why this report includes methods to estimate them. Measurements have then been done on a main battle tank, and requisite parameters have been estimated.

  • 31.
    Axelsson, Tobias
    Linköping University, Department of Electrical Engineering.
    Diagnosis System Conceptual Design Utilizing Structural Methods: Applied on a UAV’s Fuel System2004Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    To simplify troubleshooting and reliability of a process, a diagnosis system can supervise the process and alarm if any faults are detected. A diagnosis system can also identify one, or several faults, i.e. isolate faults, that may have caused the alarm. If model-based diagnosis is used, tests based on observations from the process are compared to a model of the process to diagnose the process. It can be a hard task to find which tests to be used for maximal fault detection and fault isolation. Structural Methods require not very detailed knowledge of the process to be diagnosed and can be used to find such tests early in the design of new processes. Sensors are used to get observations of a process. Therefore, sensors placed on different positions in the process gives different possibilities for observations. A specific set of sensors are in this work called a sensor configuration.

    This thesis contributes with a method to predict and examine the fault detection and fault isolation possibility. By using these two diagnosis properties, a suitable sensor configuration is computed and tests to be used in a future diagnosis system are suggested. For this task an algorithm which can be used in the design phase of diagnosis systems, and a Matlab implementation of this algorithm are described.

    In one part of this work the Matlab implementation and the algorithm are used to study how a model-based diagnosis-system can be used to supervise the fuel system in an Unmanned Aerial Vehicle (UAV).

  • 32.
    Backman, Mattias
    Linköping University, Department of Electrical Engineering.
    Utvärdering av produkter för säker autentisering i Windowsmiljö2004Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    In this report hardware based alternatives to password authentication in a Windows domain are evaluated for the needs of a certain company. In order to investigate the demands on such alternatives interviews with people concerned have been carried out. The demands which resulted from the interviews have been used to select types of hardware tokens for evaluation. Two products which offer authentication with smart cards and USB tokens have been selected and closer evaluated. These are RSA Passage which offers both hardware options and Rainbow iKey which uses USB tokens. Both products are evaluated based on the demands and additional evaluation criteria. The information from the evaluations is used to compare the products.

  • 33.
    Backskär, Daniel
    Linköping University, Department of Electrical Engineering.
    Beskrivning av systemfunktioner i kärnkraftverk med hjälp av objektorienterat modelleringsverktyg2002Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    In order to facilitate design and maintenance of such a large and complex site as a nuclear power plant, all system functions must be described in a stringent way. In the past, these descriptions consisted of text documents and logical diagrams, but today there are an increasing number of object-oriented programs available on the market which might be used for this purpose. This Master Thesis has made a closer study of one of these programs named Rational Rose. The principal of the program is to facilitate software design and development, not to create models of plants. However, using the program the same way as developing software, specifying actors then gradually extend the model with use cases, use cases diagrams etc, the same methods can be used when modelling plants.

    During this Master Thesis most of the time has been spent developing, structuring and classifying the functions composing the Feed Water Backup System of the reactor named Oskarshamn 3. A considerable amount of time was also spent to find a general structure for typical motor and valve circuits in the plant, which are also applicable for the configuration of the Feed Water Backup System. This general structure will then be used to support maintenance and to get faster decisions when new systems are designed.

    Effectuating the modernization of the nuclear power plants in Sweden, an ever- increasing use of highly software intensive systems will be introduced, which also leads to the need of finding other ways to describe those systems. A suitable method is to use Rational Rose, where the entire process, from description to final product, will be done in an integrated way. Use cases are generated and together with their related documentation they will form the description of the desired system functions.

  • 34.
    Bengtsson, Carl Johan
    Linköping University, Department of Electrical Engineering.
    SmartMedia-controller på chip2002Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    This report deals with the design of a controller for SmartMedia™ flash memory cards, based on a hardware description found in the SmartMedia™ Interface Library - SMIL.

    The design was made on logic gate level, using standard cells in OrCAD Capture. After simulation of the design in PSpice A/D, it was exported as an EDIF netlist, which was used to make a chip layout in L-Edit, a layout tool for making integrated circuits. The layout was made using a method called Standard Place and Route - SPR, where the layout tool places standard cells from a library and connects them according to the EDIF netlist.

    A netlist which could be simulated in PSpice was extracted from the finished chip layout to verify that the function of the design was the same as before the transition from schematic to layout.

    The standard cells in the library used to make the chip layout have to meet certain criteria in order for both SPR and extraction to work and this is also discussed.

  • 35.
    Bergkvist, David
    Linköping University, Department of Electrical Engineering.
    Implementation of a Watermarking Algorithm for H.264 Video Sequences2004Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    In today's video delivery and broadcast networks, issues of copyright protection have become more urgent than in analog times, since the copying of digital video does not result in the decrease in quality that occurs when analog video is copied.

    One method of copyright protection is to embed a digital code, a"watermark", into the video sequence. The watermark can then unambiguously identify the copyright holder of the video sequence. Watermarks can also be used to identify the purchaser of a video sequence, which is called "fingerprinting".

    The objective of this master thesis was to implement a program that would insert watermarks into video sequences and also detect if a given video sequence contains a givenwatermark.

    The video standard I chose to use was the H.264 standard (also known as MPEG4 AVC) as it offers a significant efficiency improvement over the previous video compression standards.

    A couple of tests that can be considered representative for most image manipulations and attacks were performed. The program passed all tests, suggesting that the watermarking mechanism of this thesis can be expected to be rather robust, at least for the video sequence used. By looking at the watermarked video sequences and comparing them to the originals, or measuring the signal to noise ratio, one can also see that the watermarks are unobtrusive. The execution times were also measured. Compared to coding and decoding a H.264 video stream, the time it takes to insert and extract watermarks was much less. Calculating a threshold takes roughly double the time as decoding the sequence, though.

  • 36.
    Bergquist, Urban
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology.
    Colour Vision and Hue for Autonomous Vehicle Guidance1999Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    We explore the use of colour for interpretation of unstructured off-road scenes. The aim is to extract driveable areas for use in an autonomous off-road vehicle in real-time. The terrain is an unstructured tropical jungle area with vegetation, water and red mud roads.

    We show that hue is both robust to changing lighting conditions and an important feature for correctly interpreting this type of scene. We believe that our method also can be deployed in other types of terrain, with minor changes, as long as the terrain is coloured and well saturated.

    Only 2D information is processed at the moment, but we aim at extending the method to also treat 3D information, by the use of stereo vision or motion.

  • 37.
    Bergström, Andreas
    Linköping University, Department of Electrical Engineering.
    Torque Modeling and Control of a Variable Compression Engine2003Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    The SAAB variable compression engine is a new engine concept that enables the fuel consumption to be radically cut by varying the compression ratio. A challenge with this new engine concept is that the compression ratio has a direct influence on the output torque, which means that a change in compression ratio also leads to a change in the torque. A torque change may be felt as a jerk in the movement of the car, and this is an undesirable effect since the driver has no control over the compression ratio.

    The aim of this master's thesis work is to develop a torque control strategy for the SAAB variable compression engine. Where the main control objective is to make the output torque behave in a desirable way despite the influence of compression ratio changes.

    The controller is developed using a design method called Internal Model Control, which is a straightforward way of both configuring a controller and determining its parameters. The controller has been implemented and evaluated in a real engine, and has proved to be able to reduce the effect of compression ratio disturbance.

  • 38.
    Bernspång, Johan
    Linköping University, Department of Electrical Engineering.
    Interfacing an external Ethernet MAC/PHY to a MicroBlaze system on a Virtex-II FPGA2004Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    Due to the development towards more dense programmable devices (FPGAs) it is today possible to fit a complete embedded system including microprocessor, bus architecture, memory, and custom peripherals onto one single reprogrammable chip, it is called a System-on-Chip (SoC). The custom peripherals can be of literally any nature from I/O interfaces to Ethernet Media Access Controllers. The latter core, however, usually consumes a big part of a good sized FPGA. The purpose of this thesis is to explore the possibilities of interfacing an FPGA based Microblaze system to an off-chip Ethernet MAC/PHY. A solution which would consume a smaller part of the targeted FPGA, and thus giving room for other on-chip peripherals or enable the use of a smaller sized FPGA. To employ a smaller FPGA is desirable since it would reduce power consumption and device price. This work includes evaluation of different available Ethernet devices, decision of interface technology, implementation of the interface, testing and verification. Since the ISA interface still is a common interface to Ethernet MAC devices a bus bridge is implemented linking the internal On-Chip Peripheral Bus (OPB) with the ISA bus. Due to delivery delays of the selected Ethernet chip a small on-chip ISA peripheral was constructed to provide a tool for the testing and verification of the bus bridge. The main result of this work is an OPB to ISA bus bridge core. The bridge was determined to work according to specification, and with this report at hand the connection of the Ethernet chip to the system should be quite straightforward.

  • 39.
    Bilbao, Héctor Uhalte
    Linköping University, Department of Electrical Engineering.
    DAB Transmission System Simulation2004Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    DAB (Digital Audio Broadcasting) is the radio digital system developed as an european standard by the ETSI, EN 300 400, based on the Eureka-147 group works, to improve the performance of the analogue radio systems (AM and FM). The system is based on the OFDM technology which allows DAB to exploit the spectrum frequencies in a better way with a higher quality of sound for mobile receivers specially. The main part of the OFDM system is based on the FFT algorithms to spread the data flow over different orthogonal carriers. The simulation has been developed in Simulink<sup>TM</sup>and Matlab<sup>TM</sup>and the layout designed follows faithfully the standard for the transmission system. The simulation can be reloaded by the user with the information presented in this thesis. Thus, this work can be continued to complete the DAB whole system simulation. The results obtained running this simulation show the main DAB system characteristics.

  • 40.
    Bjurström, Håkan
    et al.
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology.
    Svensson, Jon
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology.
    Assessment of Grapevine Vigour Using Image Processing2002Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This Master’s thesis studies the possibility of using image processing as a tool to facilitate vine management, in particular shoot counting and assessment of the grapevine canopy. Both are areas where manual inspection is done today. The thesis presents methods of capturing images and segmenting different parts of a vine. It also presents and evaluates different approaches on how shoot counting can be done. Within canopy assessment, the emphasis is on methods to estimate canopy density. Other possible assessment areas are also discussed, such as canopy colour and measurement of canopy gaps and fruit exposure. An example of a vine assessment system is given.

  • 41.
    Björk, Mårten
    et al.
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology.
    Max, Sofia
    Linköping University, Department of Electrical Engineering, Computer Vision. Linköping University, The Institute of Technology.
    ARTSY: A Reproduction Transaction System2003Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    A Transaction Reproduction System (ARTSY) is a distributed system that enables secure transactions and reproductions of digital content over an insecure network. A field of application is reproductions of visual arts: A print workshop could for example use ARTSY to print a digital image that is located at a remote museum. The purpose of this master thesis project was to propose a specification for ARTSY and to show that it is technically feasible to implement it.

    An analysis of the security threats in the ARTSY context was performed and a security model was developed. The security model was approved by a leading computer security expert. The security mechanisms that were chosen for the model were: Asymmetric cryptology, digital signatures, symmetric cryptology and a public key registry. A Software Requirements Specification was developed. It contains extra directives for image reproduction systems but it is possible to use it for an arbitrary type of reproduction system. A prototype of ARTSY was implemented using the Java programming language. The prototype uses XML to manage information and Java RMI to enable remote communication between its components. It was built as a platform independent system and it has been tested and proven to be operational on the Sun Solaris platform as well as the Win32 platform.

  • 42.
    Björklund, Magnus
    et al.
    Linköping University, Department of Electrical Engineering.
    Persson, Gun
    Linköping University, Department of Electrical Engineering.
    Diagnostiksystem i gaffeltruckar2003Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    This is a final thesis done at BT, considering one of their forklift truck models called Reflex. The first part of this report is about a preliminary investigation investigating what kind of diagnostic systems BTwants to use, and also which demands there are to meet all expectations on such system. Secondly a diagnostic system, which will show if the drive wheel is worn out, will be presented.

    In the preliminary investigation, two kinds of diagnostic systems were mentioned. These were Model based diagnosis and Predictive analysis. Model based diagnosis is based on measurements made by sensors at the truck, while predictive analysis is based more on statistics and retrieved data about the lifetime of a truck in specific environments.

    The diagnosis system for the drive wheel is based on a model made in Matlab's Simulink. Due to poor documentation, rough simplifications in the model have been made. However, one can still see the differences of principle.

    The main thought was detecting a difference in the lowest torque level from the engine, varying the diameter of the drive wheel. By measurements made directly at the truck, different torques could be observed with varying diameter of the drive wheel, varying load on the truck and varying friction in the gearbox. Using hypothesis tests, it is possible to say whether the drive wheel is worn out or not.

    Results show that if the drive wheel diameter is reduced by 25 mm, torque is reduced by 7% and if the drive wheel diameter is reduced as much as 50 mm, a torque reduction of 11% would be achieved.

  • 43.
    Björsson, Anders
    Linköping University, Department of Electrical Engineering.
    Simulation analysis of RLC/MAC for UMTS in Network Simulator version 22004Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    The Internet has mainly been interconnecting stationary computers by wired links, but an increasing number of mobile clients require wireless communication. One way to connect these clients is to use the Universal Mobile Telecommunication System, UMTS. UMTS is a third generation mobile system.

    A network can be seen as nodes interconnected by links. The functionality of the nodes can be described as a layered hierarchy. A reference model for this hierarchy was developed by OSI. In this model the second lowest layer is called data link layer. The data link layer is responsible for making the raw transmission appear error free to upper layers.

    The focus for this thesis is the data link layer in the UMTS. Compared to the data link layer in a wired scenario it contains more control and error correction mechanisms. These mechanisms use a lot of timers and triggers, which makes it very difficult to analyze them mathematically. Therefore simulation is the preferred method.

    For the simulations the network simulator version 2 was used. This is an open source discrete event simulator. It has a modularized wireless stack already implemented. This can not be used to simulate UMTS though. Some modules in this stack were replaced by a new implementation to make simulations on UMTS possible.

    Tests were performed on the new implementation and the results were what could be expected. The results were also consistent with previous research in the area.

  • 44.
    Blaauwendraad, Bart
    Linköping University, Department of Electrical Engineering.
    TIR, design and testing of a Simple GALS2002Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    Globally-asynchronous locally-synchronous (GALS) systems may become a solution for nowadays challenges in the field of VLSI design. Fully synchronous chips are becoming not feasible anymore due to clock distribution and power consumtion problems. The value of GALS lies in combination of well know synchronous design methods and relative simple asynchronous communication channels.

    The key components are the communication control ports around the synchronous modules and the stretchable clock also called a wrapper. This clock has a unbound delay and is controlled by events the asynchronous channel.

    A simple GALS system consisting of a 4-bit transmitter, integrator and receiver has been designed and layouted for a 0,35 micron CMOS proces. A 4-phase bundled protocol is used with GasP FIFO's. Novel circuits has been designed to switch from the one wire asynchronous communication of the FIFO to the 4-phase of the wrapper.

    The report also dicusses the challenges for manufature test on asynchronous designs. A test strategy for GALS systems is been devoloped.

  • 45.
    Blom, Martin
    Linköping University, Department of Electrical Engineering.
    En oscillatorbank till en lågfrekvensradar: LORA/VHF2004Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    The goal of this thesis work is to enable an existing UHF radar to operate in the VHF band instead. In order to achieve this, new coherent local oscillators are required. Different options are suggested and one of them is implemented and analyzed.

  • 46.
    Blommé, Johan
    Linköping University, Department of Electrical Engineering.
    Evaluation of biometric security systems against artificial fingers2003Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    Verification of users’ identities are normally carried out via PIN-codes or ID- cards. Biometric identification, identification of unique body features, offers an alternative solution to these methods.

    Fingerprint scanning is the most common biometric identification method used today. It uses a simple and quick method of identification and has therefore been favored instead of other biometric identification methods such as retina scan or signature verification.

    In this report biometric security systems have been evaluated based on fingerprint scanners. The evaluation method focuses on copies of real fingers, artificial fingers, as intrusion method but it also mentions currently used algorithms for identification and strengths and weaknesses in hardware solutions used.

    The artificial fingers used in the evaluation were made of gelatin, as it resembles the surface of human skin in ways of moisture, electric resistance and texture. Artificial fingers were based on ten subjects whose real fingers and artificial counterpart were tested on three different fingerprint scanners. All scanners tested accepted artificial fingers as substitutes for real fingers. Results varied between users and scanners but the artificial fingers were accepted between about one forth and half of the times.

    Techniques used in image enhancement, minutiae analysis and pattern matching are analyzed. Normalization, binarization, quality markup and low pass filtering are described within image enhancement. In minutiae analysis connectivity numbers, point identification and skeletonization (thinning algorithms) are analyzed. Within pattern matching, direction field analysis and principal component analysis are described. Finally combinations of both minutiae analysis and pattern matching, hybrid models, are mentioned.

    Based on experiments made and analysis of used techniques a recommendation for future use and development of fingerprint scanners is made.

  • 47.
    Bond, Anders
    et al.
    Linköping University, Department of Electrical Engineering.
    Påhlsson, Nils
    Linköping University, Department of Electrical Engineering.
    A Quantitative Evaluation Framework for Component Security in Distributed Information Systems2004Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    The Heimdal Framework presented in this thesis is a step towards an unambiguous framework that reveals the objective strength and weaknesses of the security of components. It provides a way to combine different aspects affecting the security of components - such as category requirements, implemented security functionality and the environment in which it operates - in a modular way, making each module replaceable in the event that a more accurate module is developed.

    The environment is assessed and quantified through a methodology presented as a part of the Heimdal Framework. The result of the evaluation is quantitative data, which can be presented with varying degrees of detail, reflecting the needs of the evaluator.

    The framework is flexible and divides the problem space into smaller, more accomplishable subtasks with the means to focus on specific problems, aspects or system scopes. The evaluation method is focusing on technological components and is based on, but not limited to, the Security Functional Requirements (SFR) of the Common Criteria.

  • 48.
    Borg, Johan
    Linköping University, Department of Electrical Engineering.
    Studies on Tuning of Integrated Wave Active Filters2003Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    The first part of this thesis contains a literature study of current tuning techniques for continuous-time integrated filters. These tuning methods are characterised by which quantity they measure, their dependence on certain characteristics of the input signal, or matching of components on chip. The structure of the different tuning schemes are explained. The merits and drawbacks as well as achieved accuracies of previous works are summarised.

    The second part is a study of wave active filters (WAFs), a less common structure for implementing active filters. In this structure the filter is realised by simulating the forward and reflected voltage waves present in the prototype filter. The main advantage of this is that the inherent low sensitivity of doubly terminated ladder-filters is better preserved than in many other structures. Two Mosfet-C realisations of Wave Active Filters have been suggested and high-level simulations have been used to compare them to the originally proposed implementation as well as a leapfrog implementation.

  • 49.
    Borg, Niklas
    Linköping University, Department of Electrical Engineering.
    Reglering av matarsystem vid höghastighetskapning2002Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    Today small metal parts are mass-produced as for example rollers in cylinder bearings. At high velocity cutting the metal is cut with a great force in a scissor-like device. Both precision and repeatability is important to be able to guarantee good quality, but from an economical point of view it is also important to keep a great manufacturing capacity. The part of the process that is most time consuming is when the metal bar, that is about to be cut, is fed to the right position. Therefore it is interesting to examine if the time used for positioning can be reduced. This thesis examines if more advanced automatic control can be used to speed up the process while maintaining the precision. In order to test and evaluate different theories, two different mathematical models have been developed. The models where implemented in the simulation program SIMULINK in MATLAB and they where compared to and adapted to data measured on the physical machine. One model is developed from physical relationships and mostly used for simulations while the other one, a condition state model, has been used for regulator design. The first question to answer was if it is at all possible to control the process any faster. When a theoretical limit was found the next step was to design a regulator to show that the theory of automatic control does not imply too great limitations. The design that was chosen was condition state feedback where the states were appraised with an observer.

    A faster system will raise the demands on cycle times and precision. To make sure that the hardware isn’t the limiting factor, design requirements have been set up. A small list of what hardware is available has also been put together (and shows that it is possible to implement such a system).

    The conclusion is that it is, theoretically, possible to radically increase the manufacturing capacity. The assumptions for this to be accomplished is especially that the uncertainty of the model is minimizedand that hardware with enough capacity can be found.

  • 50.
    Boström, Erik
    Linköping University, Department of Electrical Engineering.
    Refined Access Control in a Distributed Environment2002Independent thesis Basic level (professional degree)Student thesis
    Abstract [en]

    In the area of computer network security, standardization work has been conducted for several years. However, the sub area of access control and authorization has so far been left out of major standardizing.

    This thesis explores the ongoing standardization for access control and authorization. In addition, areas and techniques supporting access control are investigated. Access control in its basic forms is described to point out the building blocks that always have to be considered when an access policy is formulated. For readers previously unfamiliar with network security a number of basic concepts are presented. An overview of access control in public networks introduces new conditions and points out standards related to access control. None of the found standards fulfills all of our requirements at current date. The overview includes a comparison between competing products, which meet most of the stated conditions.

    In parallel with this report a prototype was developed. The purpose of the prototype was to depict how access control could be administered and to show the critical steps in formulating an access policy.

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