Analysis of possibilities to target detection by using secondarily emitted signals

One of the fundamental goals of electronic intelligence (ELINT), respectively passive surveillance systems (PSS), is the process of determining the position of the target, the output of which is to estimate the target position. It depends on the analysis of the received radio signals transmitted by the target. Information sources for long-range PSS are especially radio signals from active onboard aircraft systems or more generally flying airborne objects. Due to the physical possibilities for detection are for contemporary PSS real source of information signal shipboard radars, navigation interrogators, identification transponders, jammers and means of data transfer (Data Links). The development of aircraft is mainly focused on the real using of technologies, known collectively as STEALTH, to reduce the effective reflective surface radar aircraft, which is decisive for the detection of range to targets while reducing radio emission targets. In this category we find also Low-dimensional air targets - UVA (Unmanned Aerial Vehicle), UCAV (Unmanned Combat Air Vehicle) and other targets that have minimal reflective surface have given its geometrical dimensions. This article is focused on the analysis of signals of objects of interest in terms of their origin. There are two main groups of sources. Firstly, primary actively generated airborne signals (radar, navigation, identification, jamming, data and communication) and secondarily emitted signals generating due to reflection and scattering of the incident to the performance of the air target asynchronously or synchronously operating terrestrial or airborne transmitters.