METHOD OF TRACKING AN AERIAL TARGET UNDER THE ACTION OF A SIGNAL-LIKE WITH DOPPLER FREQUENCY MODULATION OF DRFM TYPE NOISE Russian patent published in 2020 - IPC G01S13/52 G01S7/02 G01S7/36 G01S7/41 

FIELD: data processing.

SUBSTANCE: invention relates to secondary digital processing of radar signals and can be used for tracking and identification of type of air target (AT) of aircraft with turbojet (TJE) when exposed to signal-like with Doppler frequency modulation, noise of DRFM type (digital radio-frequency memory). Method consists in the fact that reflected from aircraft AT with TJE radar signal by means of fast Fourier transformation procedure is converted into amplitude-frequency spectrum, which components are caused by reflections of signal from airframe escorted AT and low-pressure compressor (LPC) rotating parts of its power plant, as well as exposure to a signal-like DFRM type interference with Doppler frequency modulation. In area of glider components of Doppler frequencies, first, determining a first Doppler frequency count corresponding to a maximum amplitude of the spectral component of the signal spectrum which is transmitted to the input of the first Kalman filter, secondly, determining a second Doppler frequency count corresponding to an amplitude commensurate with the spectral component of the signal spectrum having a maximum amplitude in the region of glider Doppler frequencies, which is transmitted to the input of the second Kalman filter, third, determining a Doppler frequency count corresponding to a maximum amplitude of the spectrum component of the signal spectrum lying on the left per kHz units from the Doppler frequency relative to the first and second Doppler frequency samples, which is supplied to input of Kalman filter of the first compressor component of signal spectrum, which is caused by reflections of signal from impeller blades of first stage LPC. At each cycle of operation of three Kalman filters, estimating, respectively, the difference between the estimated first Doppler frequency values and the first target airship LPC first stage LPC blades with TJE blades and between the estimated second Doppler frequency values and the first stage LPC impeller blades. Difference difference moduli derivatives are determined, which are compared with a threshold value ε close to zero. Entire range of possible values of estimates of differences is a priori broken down into Q non-overlapping subranges. For K of intermediate cycles of operation of all three Kalman filters, probability P_q of falling of formed value into each of a priori formed q-th sub-range is determined. Number of the q-th sub-range for which the probability P_q is maximum is determined. This is the maximum value of P_{q max} is compared with predetermined threshold probability of target type recognition P_thr. If P_{q max}≥P_thr, decision is made on recognition of the q-type of the accompanied AT-aircraft with TJE with probability P_{q max}, not lower than the specified one, otherwise, decision is made on impossibility to recognize type of escorted AT with specified probability.

EFFECT: with probability of at least a given type of accompanied AT-aircraft with TJE under action of signal-like with Doppler frequency modulation of DRFM type interference.

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