Swedish Defence Research Agency

About: Swedish Defence Research Agency is a government organization based out in Stockholm, Sweden. It is known for research contribution in the topics: Radar & Laser. The organization has 1413 authors who have published 2731 publications receiving 56083 citations. The organization is also known as: Totalförsvarets forskningsinstitut.

GNSS spoofing detection using multiple mobile COTS receivers

Abstract: In this paper we deal with spoofing detection in GNSS receivers. We derive the optimal genie detector when the true positions are perfectly known, and the observation errors are Gaussian, as a benchmark for other detectors. The system model considers three dimensional positions, and includes correlated errors. In addition, we propose several detectors that do not need any position knowledge, that outperform recently proposed detectors in many interesting cases.

A self-tuning technique for optimization of dual band LNA

Abstract: This paper presents a self-tuning technique for optimization of a dual band LNA that can be used in a flexible RF front-end suitable for IEEE 802.11a/b/g WLAN applications. With this tuning technique the LNA can perform self-calibration for the optimal performance. A possible shift in resonance frequency due to process and temperature variations can be compensated by this method. The proposed self-tuning technique is implemented by using a simple RF detector at the LNA output. Based on the DC value provided by this detector the LNA is tuned for a maximum gain through the tuning loop, which incorporates ADC, digital base-band and DAC. We show that the tuning error can be within half LSB of ADC provided the DAC and ADC resolutions are constraint by a specified condition. For 4-bit case this value corresponds to a gain error of 0.4 dB. The LNA has been implemented in 0.2 mum GaAs process offered by OMMICtrade. In measurements the LNA achieves a gain of 15.1 dB and 21.6 dB in the upper and lower band, respectively, with corresponding NF of 3.8 dB and 2.8 dB. In the lower band the measured IIP3 is -3 dBm and 1 dB_CP is -8 dBm.

Target Detection and Classification of Small Drones by Deep Learning on Radar Micro-Doppler

Abstract: Small drones, also called mini-UAVs (Unmanned Aerial Vehicles), have become very wide-spread. In security applications it is often desirable to detect and classify them. In this paper we employ radar micro-Doppler for detection and classification of small drones. Micro-Doppler are Doppler shifts generated by the movements of parts of the target. We have used radar measurements of small drones and birds, generated TVDs (Time Velocity Diagrams), and used a deep learning classifier to distinguish between drones and birds (target detection) and types of drones (target classification) with very good results. Our deep learning classifier is an improvement in classification performance compared to our earlier boosting and SVM (Support Vector Machine) classifiers on the same data.

Acetylcholinesterases from the Disease Vectors Aedes aegypti and Anopheles gambiae: Functional Characterization and Comparisons with Vertebrate Orthologues.

Abstract: Mosquitoes of the Anopheles (An.) and Aedes (Ae.) genus are principal vectors of human diseases including malaria, dengue and yellow fever. Insecticide-based vector control is an established and important way of preventing transmission of such infections. Currently used insecticides can efficiently control mosquito populations, but there are growing concerns about emerging resistance, off-target toxicity and their ability to alter ecosystems. A potential target for the development of insecticides with reduced off-target toxicity is the cholinergic enzyme acetylcholinesterase (AChE). Herein, we report cloning, baculoviral expression and functional characterization of the wild-type AChE genes (ace-1) from An. gambiae and Ae. aegypti, including a naturally occurring insecticide-resistant (G119S) mutant of An. gambiae. Using enzymatic digestion and liquid chromatography-tandem mass spectrometry we found that the secreted proteins were post-translationally modified. The Michaelis-Menten constants and turnover numbers of the mosquito enzymes were lower than those of the orthologous AChEs from Mus musculus and Homo sapiens. We also found that the G119S substitution reduced the turnover rate of substrates and the potency of selected covalent inhibitors. Furthermore, non-covalent inhibitors were less sensitive to the G119S substitution and differentiate the mosquito enzymes from corresponding vertebrate enzymes. Our findings indicate that it may be possible to develop selective non-covalent inhibitors that effectively target both the wild-type and insecticide resistant mutants of mosquito AChE.

Small Helical Magnetic Flux-Compression Generators: Experiments and Analysis

Abstract: In order to gain experience in explosive pulsed power and to provide experimental data for modeling, a small high-explosive-driven helical magnetic flux-compression generator (FCG) was designed at the Swedish Defence Research Agency (FOI). The generator, of which three have been built, has an overall length of 300 mm and a diameter of 70 mm. It could serve as the energy source in a pulse-forming network to generate high power pulses for various loads. This paper presents the design of, and tests with, this helical FCG. The generator had an initial inductance of 23 muH and was operated into a load of 0.2 muH. The generator is charged with 0.27 kg of high explosives (PBXN-5). Various types of diagnostics were used to monitor the operation of the generator, including current probes, optical fibers, and piezo gauges. With seed currents of 5.7 and 11.2 kA, final currents of 269 and 436 kA were obtained, corresponding to current amplification factors of 47 and 39. The peak of the current was reached about 30 mus after the time of crowbar. The two generators showed only small losses in terms of 2pi-clocking. Using signals from optical fibers, the deflection angle of the armature could be determined to be 10 deg in good agreement with hydrodynamic simulations of the detonation process and the detonation velocity to be 8.7 km/s in agreement with tabulated value.