Modeling and Simulation of the Active Jammer Effect in the Crossed Array Detectors Infrared Seeker
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.
Countermeasure Detection in the Two-Color Pulsed Infrared seekers Using Pulse Number
One of the important parts of the infrared seeker is the counter countermeasure part. Seeking in a field of view with the existence of jammers is not simple and needs effective algorithms. In this paper, several methods of the detection in a crossed array trachers (CAT) seeker will be designed, simulated and evaluated. One of these methods, which is detecting the flare using the pulses number relatively to an adaptive threshold, is a novel one. .
Scintillation and phase anisoplanatism in Shack-Hartmann wavefront sensing
Adaptive optics provides a real-time compensation for atmospheric turbulence that severely limits the resolution of ground-based observation systems. The correction quality relies on a key component, that is, the wavefront sensor (WFS). When observing extended sources, WFS precision is limited by anisoplanatism effects. Anisoplanatism induces a variation of the turbulent phase and of the collected flux in the field of view. We study the effect of this phase and scintillation anisoplanatism on wavefront analysis. An analytical expression of the error induced is given in the Rytov regime. The formalism is applied to a solar and an endoatmospheric observation. Scintillation effects are generally disregarded, especially in astronomical conditions. We shall prove that this approximation is not valid with extended objects.