engleski

Independent component analysis approach to resolve the multisource limitation of the reticle based optical trackers

Reticle systems are considered to be the classical approach for estimating the position of a target in a considered field of view and are widely used in IR seekers. Due to the simplicity and low cost, since only a few detectors are used, reticle seekers are still in use and are subject of further research. However, the major disadvantage of the reticle trackers has been proven to be sensitivity on the IR countermeasures. To resolve this problem modification of optical trackers is analyzed here for a wide class of reticles that are producing frequency or amplitude modulated signals either by nutation or by spinning. When Independent Component Analysis (ICA) algorithms are applied on the outputs of appropriately modified trackers the reticle type dependent transmission functions, also called the source signals in the context of the ICA theory, can be recovered on the basis of the output signals only. Position of each optical source is obtained by applying appropriate demodulation method on the recovered source signals. The three conditions necessary for the ICA theory to work (statistical independence and non-Gaussianity of the source signals and nonsingularity of the mixing matrix) are shown to be fulfilled in principle for any kind of the reticle geometry. In relation to some IR counter-countermeasures algorithms which are based on heuristic and sometimes unrealistic assumptions (target performs no maneuvering) the approach exposed here has been proven to be theoretically consistent without any special constraints imposed on the optical sources.

coherence; independent component analysis; unsupervised neural networks; infrared reticle trackers; countermeasure; counter-countermeasure

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