Patent RU-2769970-C1 (RU)
Title: Method for polarimetric selection of decoy aerial targets
Inventor: Ambrosov Dmitrij Valerevich
IPC: G01S13/52
Filed: 2020-12-25
Granted: 2022-04-12
Abstract: FIELD: radio location. 
     SUBSTANCE: invention relates to methods for selecting autonomous decoy aerial targets and can be used to select decoy aerial targets based on the polarisation characteristics of the reflected signals in multichannel pulse-doppler radio location detection and tracking systems. In the claimed method, two pulse sequences are emitted alternately in the direction of each selected target by the transceiver channels of a radio location station with two active phased antenna arrays with horizontal and vertical polarisations of the electromagnetic waves: the first one with step frequency modulation to form a high-resolution range portrait and the second one with linear frequency modulation to form a spectral-doppler portrait of the m th  target. M targets are therein simultaneously tracked by the method for sequential orientation of the beams of the two active phased antenna arrays with horizontal and vertical polarisations of the electromagnetic waves towards each target. The pulse sequences reflected from the m th  target with step frequency modulation and with linear frequency modulation, the amplitudes and doppler frequencies whereof are stored in the random access memory in the corresponding private two-dimensional data arrays, are simultaneously received by two channels. A three-dimensional general array W is formed from the private arrays for individual m th  targets, wherefrom high-resolution range portraits and spectral-doppler portraits are received for each m th  target at four polarisations (two collinear and two orthogonal ones), on the basis whereof multi-frequency polarimetric range-doppler radio location portraits are formed. Estimates of the total difference of the multi-frequency polarimetric range-doppler radio location portraits are then determined in each resolution element, the average values thereof for the m th  target are calculated within the private data arrays, and a decision is made on the trueness of the aerial target. A clustering algorithm is therein used, e.g., k-means, wherein the initial cluster centres of a true target and a decoy target are set as the maximum and minimum of the entire sample of average values of the total difference values of the multi-frequency polarimetric range-doppler radio location portraits of M targets, the average values thereof are distributed into two clusters - of true and decoy air targets - based on the criterion of the smallest distance to the mass centres of the clusters, the cluster centres are recalculated iteratively until said centres become constant values. 
     EFFECT: increase in the probability of correct selection of MALD-type autonomous decoy air targets due to the additional accounting for the polarisation differences when the effect of secondary doppler modulation of the probing signal reflected from the aircraft power unit occurs, as well as the application of a clustering algorithm, e.g., k-means or Fuzzy C-means, when making a decision on the trueness of an aerial target. 
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