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.

Performance of laser tracking of small targets during turbulence and beam jitter

Abstract: Small target detection and tracking are important for laser radars in many applications such as Directed Infrared Countermeasures (DIRCM), fire control, target recognition and free space laser communications. The detection and tracking performance is depending on the mode of detection, signal to noise ratio, target signal statistics, beam jitter and turbulence induced intensity variations. We will show results of the rms tracking error vs SNR primarily for direct detection systems. For the general case of a certain signal and noise probability density functions (pdf) it is hard to obtain analytical solutions for the mean and variances of the estimates for the rms tracking error. We have therefore used numerical simulations to illustrate how the pdf and SNR will affect the tracking accuracy. A manifold of gamma functions and other pdf:s can be used to characterize the signal distributions to get a first hand on tracking performance. The results are presented as tracking errors vs the angular spot size of the laser beam in the tracking detector plane. We have also investigated the beam optimization problem for target detection and “power in bucket”, that is maximizing the laser energy at the target. We find that there are optimum beam sizes (w) vs. the rms jitter (σ) and that optimum w/σ (minimizing the false alarm rate for a given detection probability Pd) typically fall in the region 1-3 depending on probability of detection and the representative pdf for the application in mind.

Calculation of IR signatures from airborne vehicles

Abstract: To be able to predict the IR signature of an aircraft, the heat radiated, in the form of IR radiation, has to be calculated. A program package, SIGGE, has been developed at FOI for this purpose. In this paper, the code will be presented together with some results from verification, validation and one application.

A Comparison of Two Recorders for Obtaining In-flight Heart Rate Data

Abstract: Measurement of mental workload has been widely used for evaluation of aircraft design, mission analysis and assessment of pilot performance during flight operations. Heart rate is the psychophysiological measure that has been most frequently used for this purpose. The risk of interference with flight safety and pilot performance, as well as the generally constrained access to flights, make it difficult for researchers to collect in-flight heart rate data. Thus, this study was carried out to investigate whether small, non-intrusive sports recorders can be used for in-flight data collection for research purposes. Data was collected from real and simulated flights with student pilots using the Polar Team System sports recorder and the Vitaport II, a clinical and research recording device. Comparison of the data shows that in-flight heart rate data from the smaller and less intrusive sports recorder have a correlation of.981 with that from the clinical recorder, thus indicating that the sports recorder is reliable and cost-effective for obtaining heart rate data for many research situations.