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 & Synthetic aperture radar. The organization has 1413 authors who have published 2731 publications receiving 56083 citations. The organization is also known as: Totalförsvarets forskningsinstitut.

Photon-counting panoramic three-dimensional imaging using a Geiger-mode avalanche photodiode array

Abstract: A lidar system based on a photon-counting Geiger-mode avalanche photodiode (GmAPD) array can provide high range resolution three-dimensional imaging. The small number of pixels in the GmAPD array limits the size of measured scenes compared to passive cameras. Here, the performance of rapid panoramic imaging of larger scenes is investigated. Controlled environment indoor measurement at up to 24 m range is used to validate the principle. Outdoor daylight measurements of natural targets at 230 to 340 m range are performed to test the capability of the measurement system. A 20 deg by 1.8 deg scene is imaged with 0.25-mrad lateral resolution in 4 s. The standard deviation of point to plane distances for a flat wall in the outdoor measurement is 10.6 mm, giving an estimate of the achievable relative range accuracy, even if this will depend on the signal-to-noise ratio. A radiometric model is used to estimate the performance of an upgraded optimized system and the necessary laser power for imaging at longer ranges in both day and night conditions.

SE-IT joint M-AESA program: Overview and status

Abstract: The Multi-function Phased Array (M-AESA) program is a joint SE-IT initiative for the development of a capability driven multifunction phased array system concept. This paper will present the progress the M-AESA research and development program has made over the last three years and it follows the paper “New concepts for MRFS evolutionary trends. The M-AESA program: A joint IT-SE capability driven approach” by V. Carulli et al. presented at the Radar Conference 2008 in Rome [1]. The program, based on a number of different national initiatives, benefits from different cultural approaches and perspectives, and aims to lead an initiative in Europe for such a new family of RF systems. An overview and status of this unique R&D partnership will be discussed with a mission of evaluating new technology and system architecture for developing the next generation phased array antenna system capable of exploiting the most relevant operational functions (Radar, EW, Comm) according to the operational scenarios. However, a number of technical, operational and cost issues are still remaining to be addressed before M-AESA can become a reality.

Experimental study of mid-IR laser beam wander close to a jet engine exhaust

Abstract: An increasing interest in lasers placed on aircrafts for active countermeasures and active imaging is observed. There remain unsolved issues regarding the propagation effects close to the jet engine exhaust and the possibilities of compensating them with adaptive optics. Laser beam propagation experiments parallel to the exhaust of a downscaled jet engine test rig have been performed. The experiments were carried out with nanosecond laser pulses at 1.6 and 3.5 μm wavelength. The laser spots were projected on a screen and the centroid motion were imaged by cameras. Root mean square magnitudes of the beam wander between 50 and 150 μrad were observed for different engine conditions and geometries. The 3.5 μm system had a frame rate of 607 Hz and could partly resolve the time variation of the beam wander. A correlation time (50 %) of 3.5 ms was observed for the beam wander. Deflections of several hundred μrad due to the average gradients in temperature and pressure were also found when the engine was turned on. In addition to beam wander intensity scintillations has been studied.

Multivariate data analysis of fluorescence signals from biological aerosols

Abstract: This paper describes the use of multivariate data analysis of multiwavelength fluorescence measurements of biological aerosols collected by an air to liquid cyclone sampler. The enriched aerosol suspension was analyzed in a flow cell by a commercial spectrofluorometer at eight different wavelength combinations. The data were obtained from the disseminations of biological simulants at the 6th Joint Field Trials at Defence Research Establishment Suffield, Ralston, Alberta, Canada. The measurement concept was to use intrinsic biological fluorescence to distinguish between the different simulants as well as to distinguish them from interfering particles such as smoke and dust. Fluorescence data were analyzed using principal component analysis. © 2001 John Wiley & Sons, Inc. Field Analyt Chem Technol 5: 171–176, 2001

Jamming and interference vulnerability of IEEE 802.11p

Abstract: The IEEE 802.11p standard will in the next years be introduced for vehicle-to-vehicle and vehicle-to-infrastructure (V2X) communication. Some of the services in this standard are dedicated to active road safety applications and can therefore be sensitive to radio interference. Since the system is based on Automatic Repeat Request (ARQ) and Carrier Sense Multiple Access (CSMA), interference problems will, for a constant data rate, appear as packet delays and there is a risk that the packet delay may violate critical delay requirements defined for future safety related applications. In this work we have analyzed interference signal approximations for system performance predictions and the impact on the IEEE 802.11p system in terms of bit and packet error probability and packet delays.