Seeking in a field of view (FOV) is influenced by the existence of jammers, noise, shine background or flying perturbations. All these factors may push the target out of the FOV and cause missing the target. In all the seekers the FOV is not fully exploited which means the target can be missed before becoming out of the FOV, this results of the nonlinearity of the reticle structure. In this paper, a novel method of the target position detection a crossed four slits or crossed array detectors (CAT) seeker will be designed, simulated and evaluated. The idea of this method depends on dividing the FOV into main regions up to a certain parameter, which is the pulses number; then, each main region will be divided into sub-regions up to a second parameter which will be the pulses distribution a spin period. The errors sources will be discussed and evaluated. Other new idea will be applied which is exploiting some area of the FOV where a part of the position data is missed in the information signal by pushing the target to the region where the information signal carries the total position data.

IR active jammers or the directed infrared counter measures(DIRCM)generate IR signals which attack the guidance signals passed to the sensors in IR-guided weapons. They provide IR signals with appropriate frequency, phase and intensity which will be superposed on those produced by the IR energy of the target passing through the reticle. When both the jamming signal and the modulated target energy signals are received by the missile"s IR sensor, they cause the tracker to produce incorrect guidance commands and push the target out of the field of view (FOV). In this paper, the seeker signals of a crossed four slits or crossed array detectors (CAT) infrared seeker will be simulated. Then the active jammer signal is modeled and simulated. After that, the effect of all the active jammer parameters will be discussed and simulated. Finally, the conditions or the ranges of these parameters in which the active jammer can affect the seeking process will be stated.

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Let q be a power of a prime and let F q be the finite field consisting of q elements. We establish new explicit estimates on Gauss sums of the form S n (a) = x∈Fq ψ a (x n ), where ψ a is a nontrivial additive character. In particular, we show that one has a nontrivial upper bound on |S n (a)| for certain values of n of order up to q 1/2+1/68 . Our results improve on the previous best known bound, due to Zhelezov.