| 1. |
- Falk, Johan, et al.
(författare)
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Direction Finding for Electronic Warfare Systems Using the Phase of the Cross Spectral Density
- 2002
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Ingår i: RadioVetenskap och Kommunikation (RVK). ; , s. 264-268
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Konferensbidrag (refereegranskat)abstract
- In modern electronic warfare systems there is a need for direction-finding of transmitters using waveforms for military stealth communication. In this paper, a correlation-based method is investigated utilizing the phase of the cross spectral density to estimate the time-difference-of-arrival from a two-channel digital receiver. A least squares method is reviewed, and its performance is investigated by theoretical analysisand by Monte-Carlo simulations. Proper Cramér-Raobounds are derived. It is shown that the method is statistically efficient for flat spectrum signals. The method is found to be a promising method for use against military communication in an electronic warfare direction-finding system.
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| 2. |
- Gustafsson, Fredrik, et al.
(författare)
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Particle Filters for Positioning, Navigation and Tracking
- 2002
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Ingår i: IEEE Transactions on Signal Processing. - : Institute of Electrical and Electronics Engineers (IEEE). - 1053-587X .- 1941-0476. ; 50:2, s. 425-437
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Tidskriftsartikel (refereegranskat)abstract
- A framework for positioning, navigation and tracking problems using particle filters (sequential Monte Carlo methods) is developed. It consists of a class of motion models and a general non-linear measurement equation in position. A general algorithm is presented, which is parsimonious with the particle dimension. It is based on marginalization, enabling a Kalman filter to estimate all position derivatives, and the particle filter becomes low-dimensional. This is of utmost importance for high-performance real-time applications. Automotive and airborne applications illustrate numerically the advantage over classical Kalman filter based algorithms. Here the use of non-linear models and non-Gaussian noise is the main explanation for the improvement in accuracy. More specifically, we describe how the technique of map matching is used to match an aircraft's elevation profile to a digital elevation map, and a car's horizontal driven path to a street map. In both cases, real-time implementations are available, and tests have shown that the accuracy in both cases is comparable to satellite navigation (as GPS), but with higher integrity. Based on simulations, we also argue how the particle filter can be used for positioning based on cellular phone measurements, for integrated navigation in aircraft, and for target tracking in aircraft and cars. Finally, the particle filter enables a promising solution to the combined task of navigation and tracking, with possible application to airborne hunting and collision avoidance systems in cars.
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| 3. |
- Jansson, Johan, et al.
(författare)
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A discrete mechanics model for deformable bodies
- 2002
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Ingår i: Computer-Aided Design. - 0010-4485 .- 1879-2685. ; 34:12, s. 913-928
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Tidskriftsartikel (refereegranskat)abstract
- This paper describes the theory and implications of a discrete mechanics model for deformable bodies, incorporating behavior such as motion, collision, deformation, etc. The model is fundamentally based on inter-atomic interaction, and recursively reduces resolution by approximating collections of many high-resolution elements with fewer lower-resolution elements. The model can be viewed as an extended mass-spring model. We begin by examining the domain of conceptual design, and find there is a need for physics based simulation, both for interactive shape modeling and analysis. We then proceed with describing a theoretical base for our model, as well as pragmatic additions. Applications in both interactive physics based shape modeling and analysis are presented. The model is aimed at conceptual mechanical design, rapid prototyping, or similar areas where adherence to physical principles, generality and simplicity are more important than metric correctness.
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| 4. |
- Jansson, Patrik, 1972, et al.
(författare)
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Polytypic Data Conversion Programs
- 2002
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Ingår i: Science of Computer Programming. - 0167-6423. ; 43:1, s. 35-75
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Tidskriftsartikel (refereegranskat)abstract
- Several generic programs for converting values from regular datatypes to some other format, together with their corresponding inverses, are constructed. Among the formats considered are shape plus contents, compact bit streams and pretty printed strings. The different data conversion programs are constructed using John Hughes arrow combinators along with a proof that printing (from a regular datatype to another format) followed by parsing (from that format back to the regular datatype) is the identity. The printers and parsers are described in PolyP, a polytypic extension of the functional language Haskell.
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| 5. |
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