V.A. Gandurin, V.V. Filonenko
One of the basic directions of radar perfection is increase of completeness and reliability of the information on observable objects. At radar-tracking supervision of air space after target detection frequently it is required to make the decision on its numerical structure. The traditional way of the decision of such problem is a reduction of the resolved volume. From another point of view, by means of modern methods of spectrum and time analysis there is a possibility of definition of a target structure which is in limits of the radar resolved volume. The developed algorithm of a target recognition by a principle «single - group» is based on the analysis of differences of a spectrum and time realisation of the investigated target echo-signal from corresponding characteristics of a single air target standard signal. Degree of difference of two signals can be estimated by a finding of the integral squares of differences of frequency (time) countings of signals. The threshold of decision-making on Air Group Target (AGT) presence is established by Neyman-Pearson criterion. Research of efficiency of algorithm of AGT recognition was carry out by modelling on its input of a mix of a signal from two closely set targets with white gaussian noise. Staggering of the signals in time area it was measured in parts from the probing pulse duration, and in frequency - in parts from width of a pass-band of the Doppler-frequency filter. Results are that AGT from two targets can be correctly recognized with probability 0.6 and more at staggering 0.5 and the relation “signal-noise” from 22 dB. At increase of the relation “signal-noise” to 30 - 35 dB AGT is recognized at staggering from 0.15. In the presence of four targets in the radar resolved volume AGT it is recognized with probability 0.6 at the relation "signal-noise" 17 dB, and at 25 dB the probability of correct recognition AGT exceeds 0.9. The described algorithm of AGT recognition can be applied by working out perspective and modernization modern radar of airborn early warning and control system.