The Research Of Detection Capability Of Airborne Remote Infrared Search And Track System

Airborne Infrared Search and Track(IRST) systems are designed to automatically detect, locate, and track infrared targets. The infrared search and track system has many advantages such as passive detection, covert, anti-electronic interference ability, work around the clock and other characteristics. IRST can not only be used to search and track ground, air or sea targets, but also provide objective information to the close-in weapon system. Currently it is widely used in military field. Airborne IRST system must have a large enough operating distance to ensure that it is able to detect and do well in advance when the enemy aircraft or missiles attack.The main factors that affect the detecting ability of the Airborne IRST system are: the infrared radiation characteristics of the target and background, the attenuation of the atmosphere to the infrared radiation, the performance of the optical system and the detector. In this paper, we analyzed not only the infrared radiation characteristics of the aircraft, but also the radiation characteristics of the sky, the sea and the ground background. We utilized MODTRAN software to simulate the atmosphere on infrared radiation absorption and scattering and the atmospheric transmission rate under different conditions. We found that under normal circumstances the long wave infrared transmittance is better than that of the medium wave infrared and the medium wave infrared transmission rate is affected by the water vapor. What`s more, we described the importance of SNR and NETD in band selection, and analyzed how to select the optical parameters.For the point target range model, the effect of imaging dispersion and path radiation is considered. We established the point target range model of the IRST system based on the contrast and compared the results of the model and the results of the field experiments. The comparison results show that the model has a certain practicality. The model of MRTD model, which is the distance model of extended source target, is improved. Taking the tank as the target, this paper introduced the process of the operating distance of extended source target and the results are consistent with the experimental results.Finally, in order to easily and quickly calculate the radiance of target or background, the atmospheric transmittance, SNR, NETD, MRTD, the operating range and other parameters. The program aiming at calculating the operating range of IRST is presented which provides the theory basis for the system design and application as well as the synthetic performance evaluation.