This master thesis is as a final project in the Division of Computer Engineering at the Department of Electrical of Engineering, Linköping University, Sweden. The purpose of the project is to set up a baseband behavioral model for a Bluetooth system based on standards. In the model, synchronization in demodulation part has been focused on. Simulation results are analyzed later in the report to see how the method in demodulation works. Some suggestions and future works for receiver are provided to improve the performances of the model.

With the advance of the modern information society, the importance of reliable identity authentication has increased dramatically. Using biometrics as a means for verifying the identity of a person increases both the security and the convenience of the systems. By using yourself to verify your identity such risks as lost keys and misplaced passwords are removed and by virtue of this, convenience is also increased. The most mature and well-developed biometric technique is fingerprint recognition. Fingerprints are unique for each individual and they do not change over time, which is very desirable in this application. There are multitudes of approaches to fingerprint recognition, most of which work by identifying so called minutiae and match fingerprints based on these. In this diploma work, two alternative methods for locating distinct features in fingerprint images have been evaluated. The Template Correlation Method is based on the correlation between the image and templates created to approximate the homogenous ridge/valley areas in the fingerprint. The high-dimension of the feature vectors from correlation is reduced through principal component analysis. By visualising the dimension reduced data by ordinary plotting and observing the result classification is performed by locating anomalies in feature space, where distinct features are located away from the non-distinct. The Circular Sampling Method works by sampling in concentric circles around selected points in the image and evaluating the frequency content of the resulting functions. Each images used here contains 30400 pixels which leads to sampling in many points that are of no interest. By selecting the sampling points this number can be reduced. Two approaches to sampling points selection has been evaluated. The first restricts sampling to occur only along valley bottoms of the image, whereas the second uses orientation histograms to select regions where there is no single dominant direction as sampling positions. For each sampling position an intensity function is achieved by circular sampling and a frequency spectrum of this function is achieved through the Fast Fourier Transform. Applying criteria to the relationships of the frequency components classifies each sampling location as either distinct or non-distinct. Using a cyclic approach to evaluate the methods and their potential makes selection at various stages possible. Only the Circular Sampling Method survived the first cycle, and therefore all tests from that point on are performed on thismethod alone. Two main errors arise from the tests, where the most prominent being the number of spurious points located by the method. The second, which is equally serious but not as common, is when the method misclassifies visually distinct features as non-distinct. Regardless of the problems, these tests indicate that the method holds potential but that it needs to be subject to further testing and optimisation. These tests should focus on the three main properties of the method: noise sensitivity, radial dependency and translation sensitivity.

This study has been carried out as a part of the EC funded project, SMARTDOC IST-2000-28137, with the objective of developing application components that provide highly interactive visualization and collaboration functionalities. The low-level components from the graphics library AVS OpenViz 2.0 are used as the development basis. The application components can be inserted into electronic documents that allow embedded controls such as web documents or Microsoft Word or PowerPoint documents. Instead of displaying results as static images, a SMARTDOC component provides the ability to visualize data and interact with it inside the document. Although the principal goal of the SMARTDOC project is to create components in a number of different application domains this study concentrates on developing a medical imaging application component in collaboration with the project partners AETmed and professor Alan Jackson at the University of Manchester. By incorporating the application component into patient reports, the clinicians are provided the ability to interact with the 3D data that is described in the reports. To improve the usability of the component, it makes use of a visual user interface (VUI), which gives the user the ability to interact and change parameters directly in the visualization process. Collaborative work over geographical distances is an area that is becoming increasingly common and thus more interesting. As the availability of bandwidth has increased and the communication technologies have advanced, many companies express their interest for this new practical method of work. A company with offices in different countries would benefit from collaborative techniques providing closer cooperation within the company. Specialized institutions and laboratories could gather much experience and information through collaborative research. Medical imaging and visualization technique are areas where distinct disciplines such as networking, user interfaces and 3D visualization naturally can be fused together in order to develop collaborative environments. The visualization components developed within the SMARTDOC project will be the foundation for collaborative application components integrated with the Microsoft DirectX® multimedia library. In the medical imaging area, collaborative work can be used to improve diagnoses, journaling and teaching. This study focuses on developing a prototype of an interactive visualization component for 3D medical imaging and creating a collaborative environment using a multimedia library originally meant for network gaming.

Radar warning systems are life saving equipment in modern fighter aircraft. It is therefore vital that the system can tell the difference between a threat genuine frequency) and a false signal (spurious frequency). This thesis presents a model aimed at predicting the frequencies and other parameters in the RF converter of the radar warning system. The components of the RF converter have been studied, measured, and modelled. The modelling tool has been the Simulink toolbox for Matlab. Extreme accuracy has been sacrificed in order to make the model easy to use for the working engineer. Instead, this model presents a rough estimate of some of the most important properties of the radar warning system with just a few data sheet figures as input. The simulation results are satisfactory as a whole. Simulink is the limiting factor in the implementation of the model. Significantly improved results can probably be obtained by working in another software environment.

There are 12 weather radars operated jointly by smhi and the Swedish Armed Forces in Sweden. Data from them are used for short term forecasting and analysis. The traditional way of viewing data from the radars is in 2D images, even though 3D polar volumes are delivered from the radars. The purpose of this work is to develop an application for 3D viewing of weather radar data. There are basically three approaches to visualization of volumetric data, such as radar data: slicing with cross-sectional planes, surface extraction, and volume rendering. The application developed during this project supports variations on all three approaches. Different objects, e.g. horizontal and vertical planes, isosurfaces, or volume rendering objects, can be added to a 3D scene and viewed simultaneously from any angle. Parameters of the objects can be set using a graphical user interface and a few different plots can be generated. Compared to the traditional 2D products used by meteorologists when analyzing radar data, the 3D scenes add information that makes it easier for the users to understand the given weather situations. Demonstrations and discussions with meteorologists have rendered positive reactions. The application will be installed and evaluated at Arlanda airport in Sweden.

Volume rendering applications are used in medical imaging in order to facilitate the analysis of three-dimensional image data. This study focuses on how to improve the usability of graphical user interfaces of these systems, by gathering user requirements. This is achieved by evaluations of existing systems, together with interviews and observations at clinics in Sweden that use volume rendering to some extent. The usability of the applications of today is not sufficient, according to the users participating in this study. This is due to a wide range of reasons. One reason is that the graphical user interface is not intuitive. Another reason is that the users do not rely on the technique to produce sufficient results that can be used in the diagnostic process. The issue of user confidence is mainly due to the problem of the generation and user control of the transfer functions used in volume rendering. Based on the results of the evaluation a graphical user interface, including the most important and frequently used functions, is designed. A suggestion for how the transfer function can be generated is presented.

The Swedish field of digital X-ray imaging has since several years relied heavily on distributed information systems and digital storage containers. To ensure accurate and safe radiological reporting, Swedish software-firm eCare AB delivers a system called Feedback—the first and only quality assurance IT support product of its kind. This thesis covers several aspects of the design and implementation of future versions of this software platform. The focus lies on distributed directory services and models for secure and robust data propagation in TCP/IP networks. For data propagation, a new application, InfoBroker, has been designed and implemented to facilitate integration between Feedback and other medical IT support systems. The directory services, introduced in this thesis as the Feedback Directory Services, have been designed on the architectural level. A combination of CORBA and Java Enterprise Edition is suggested as the implementation platform.

To be able to evaluate different radio waveforms in a laboratory environment FOI in Linköping has developed an experimental system for radio communication called Rasmus. The system consists of a transmitter, a channel emulator and a receiver. The transmitter modulates a digital signal to a desired analogue waveform. The channel emulator is used to simulate a real radio channel. The channel emulator distorts the signal by splitting it up in several propagation paths. Each path has its own statistical distribution, delay and so on. The receiver digitises the signal and saves it in a memory. Analysis of the signal is performed in non-real time. The system has some limitations concerning signal bandwidths and channel models. This Master Thesis deals with the problem of scaling the radio channel (with respect to noise, Doppler shift and fading) in order to examine signals that have properties outside the normal operation of the Rasmus system. The radio channel studied is a Rayleigh fading channel with two independent propagation paths. A differentially modulated QPSK signal is used as input to the channel. The signal is filtered through root-raised-cosine filter in the transmitter and receiver to reduce the effect of inter-symbol interference. Theoretical calculations result in a method, that describe which parameters that should be scaled and how they should be scaled. Simulations are carried out in order to verify the method.

Slumptalsgeneratorer är bland de viktigaste byggblocken inom dagens säkerhetssystem och infrastruktur. Det finns dock en uppsjö av varierande implementeringsmodeller i såväl mjukvara som hårdvara. Att konstruera en slumptalsgenerator som har tillträckligt bra egenskaper för att användas i säkerhetssystem är inte någon trivial uppgift. I denna rapport diskuteras de två huvud metoderna att generera slumptal, dels i mjukvara (PRNG), dels i hårdvara (TRNG). Olika synvinklar och angreppssätt att generera och testa slumptal diskuteras och utvärderas. Dessutom diskuteras för- och nackdelarna med de olika generatorerna och hur dessa kan vara sårbara om inte försiktighetsåtgärder vidtas. Resultatet antyder på att valet av en slumptalsgenerator är högst beroende på den applikation dessa slumptal ska användas i. Det rekommenderas dock att man använder en TRNG (hårdvaru-generatorer) för att seeda en PRNG (Pseudo-Random Number Generator) eller att använda sig av en TRNG och då kompensera för den skeva sannolikhetsfördelningen som uppstår.

The Global System for Mobile Communications (GSM) is the most widely used cellular technology in the world. Approximately 800 million people around the world are using GSM for different purposes, but mostly for voice communication and SMS. For GSM, like many other widely used systems, security is crucial. The security involves mechanisms used to protect the different shareholders, like subscribers and service providers. The aspects of security that this report covers are mainly anonymity, authentication and confidentiality. The important aspects of the system that need protection are described, along with the implementation of mechanisms used for the protection. It appears that many of the very valuable aspects of GSM can be attacked. The anonymity of a GSM user is compromised resulting in the attacker being able to observe the time, rate, length, sources or destinations of e g calls. Even tracking a subscriber’s movements becomes possible. However, a passive attack is not sufficient to perform these attacks. The attacker needs to mount an active attack using equipment offering base station functionality. Authentication is a crucial aspect of a wireless communication system due to the nature of the medium used, i e the radio link that is available to every one and not only the legitimate entities. Even the authentication mechanisms are attacked. It is possible to clone a subscription either by having physical access to the smart card or over the air interface. Cloning a subscription over the air requires base station functionality. The most obvious threat against communication systems is eavesdropping on conversations. The privacy of GSM conversations is protected using some version of the A5 algorithm. There are several impressive cryptanalytical attacks against these algorithms, that break the encryption and make it possible to eavesdrop in real-time. Most of these algorithms require, however, extensive computation power and unrealistic quantities of known plaintext, which make it difficult to use them in practice. Difficulties using cryptanalytical attacks to break the confidentiality of GSM calls does not mean that conversations are well protected. Loopholes in the protocols used in GSM make it possible for an outsider, with access to sufficient equipment, to eavesdrop on conversations in real-time. In the presence of these threats and vulnerabilities it is justified to wonder whether GSM provides sufficient security for users with very valuable information to communicate. These users may be military organisations, senior management personnel in large companies etc. GSM’s current security model does note provide sufficient protection for these entities. An additional layer of security should be added to the current security model.