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Ivica Kopriva Harold Szu
email: ivica.kopriva@public.srce.hr email: szuh@onr.navy.mil
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. However, the disadvantage
of the reticle trackers has been overly sensitivity to manmade
clutters. We show that the nonlinear coherent version of
Independent Component Analysis (ICA) theory can perhaps
help alleviate the problem. When the processing device is
redesigned properly by a bandpass filtering, the output signals
are linear convolutive of the reticle transmission functions (rtf)
considered as the unknown input source s i (t) signals in the
context of ICA. That enables ICA neural network to be applied
on the optical tracker output signals x i (t) giving on its outputs
recovered rtf s (t). Position of each optical source is obtained
by applying appropriate demodulation method on the
recovered source signals. The contribution of this paper is
demonstrating that the coherence between optical sources
results in a nonlinear ICA problem that becomes linearized,
when the optical fields are incoherent, or, when the proper
design of the optical tracker converts the nonlinear coherent
model into linear one by bandpass filtering operation.
Consequently, the multisource limitation of the reticle based
optical trackers can in principle be overcome for both coherent
and incoherent optical sources. We therefore conclude that
requirements necessary for the ICA theory to work are fulfilled
for both coherent and incoherent optical sources.