V.A. Solovjov, M.V. Zhendarev, A.V. Kypreev, I.V. Yakimenko

The basis of any information system for air traffic surveillance is radars ensuring the detection and measurement of the coordinates of aerial targets. However, radars are rather complex and bulky devices, the operation of them is unsafe (safeless) for staff and the personnel. Instruments of optical range including opto-electronic devices of the infrared wavelength spectrum operating in a passive mode, i.e. without the emission of electromagnetic energy into space are used nowadays as the alternative and the backup means to radar stations. Such devices in their range give up to radiolocation devices but are able to have an advantage in cost, in security and safety. Last decade along with traditional manned aircraft unmanned aerial vehicles (UAVs) are widely introduced into practice, which may be used both as for aerial terrain reconnaissance, look for the objectives, monitor remoting of natural resources and for military purposes. Their distinctive features are: small size, low power motor propulsion system, the use of composite materials in their manufacture. This makes the detection of the UAVs by means of radars impossible. To evaluate the detection possibilities of unmanned aerial vehicles by means of opto-electronic devices optoelectronic devices of infrared wavelength unless possible due to the absence of any information about the characteristics of self-radiation of such air targets. In this connection there is a need for research related to the experimental determination of radiant intensity of unmanned aircraft in flight and evaluation the possibility of detection by means of opto-electronic devices infrared wavelength. One of the possible solutions to solve the problem of UAVs detection by means of opto-electronic devices is the use of thermal imagers. To perform the research mentioned above, the main efforts have been focused on the following tasks: study of previously developed experimental techniques of energy radiance and radiant intensity of aircraft; study of the methods of processing the results of in-situ measurements and the need to make improvements to techniques; conduct in-situ measurements of radiation brightness of UAVs in flight; modeling the detection process of a new type of aerial target - an unmanned aircraft and construction of its expected detection zone by infrared detector with the given parameters. Since the factors affecting the process of target detection in passive mode are a lot of, it is advisable during the design to carry out simulation mathematical modeling of UAVs detection by a developed detector at various flight and meteorological conditions. To perform imitative modeling of detection process of aerial target it should be available along with the spatial distribution of the background radiation of the sky, the dependence of the energy intensity of the aircraft in flight from the angle of its line-of-site view with the respect to the point of observation, i.e. the mathematical model of radiation. Mathematical models of the radiation background of a cloudy sky have been obtained earlier during experimental work. In-situ measurements of radiation characteristics of the unmanned aircraft \"Semel-006\" was conducted in October 27, 2010 in the airfield \"South\" (Smolensk).The object of research was the UAV \"Semel-006\", which flies in \"boxes\" along the take-off runway both on head-on and slewing courses relative to the point of observation. In a number of cases flights were performed at a constant altitude (150-1600 m.) and several flis-over were conducted with a climb and reduction, which allows to carry out measurements during flights on course angles close to 0 or 180º. The measurements were made by using a mobile measuring-computing system described above. The given results of in-situ measurements in future were processed. This resulted in the radiation model UAV as a dependence of the force of radiation from the aircraft angles of view. To solve the problems of development perspective opto-electronic detectors of infrared waves in passive mode, it is necessary to justify a choice of optical systems, radiant energy receiver, signal processing means, etc. Expected types of aerial targets should be taken into account, their flight trajectories, because of these factors radiance (energy) of aircraft own emission depends on. Besides, you also need to take into account the characteristics of radiation from a cloudy sky, against which the air targets will be observed, i.e. the optical interference of natural origin. Obtained data on the basis of experiment of UAVs given models of radiation can be used in future to evaluate the detection expected range of air targets with opto-electronic devices operating in the infrared wavelength range. Error of models does not exceed 10% of the estimating value of the radiant intensity of UAVs. Most of errors are observed at the sight of target on head-on and slewing courses at course parameter close to 0 and the low elevation angles (1-2°). In other cases the mean-root square error in determining the strength of the radiation is less than 10%.