METHOD OF AIRCRAFT WITH TURBOJET ENGINE TYPE IDENTIFICATION IN PULSE-DOPPLER RADAR STATION UNDER ACTION OF SPEED-ESCAPING INTERFERENCE

摘要

FIELD: secondary processing of radar signals.;SUBSTANCE: method consists in that a signal reflected from an aircraft with a TJE from an output of a pulse-Doppler RLS receiver at an intermediate frequency is subjected to narrow-band Doppler filtration based on a Fast Fourier Transform (FFT) and is converted into amplitude-frequency spectrum of reflection of signal from aircraft airframe with turbojet engine and rotating blades of impeller of low-pressure compressor (LPC) of its power plant. Doppler frequency count is determined, which corresponds to maximum amplitude of spectral component of reflection signal spectrum from airframe. In the first Kalman filter, the Doppler frequency ^{^}F^ν_a(k) of the signal reflections from the airframe is estimated, in the second Kalman filter—evaluation of Doppler frequency ^{^}F_i(k) of signal reflections from impeller blades of first stage LPC of aircraft power plant, in third Kalman filter—assessment of range R(k) to aircraft, calculating a difference module of estimates ^{^}F^ν_a(k) and ^{^}F_i(k) based on the derived range estimate, its comparison with a threshold close to zero. If the threshold is not exceeded, the conclusion is made that there is no effect of rate-escalating interference, otherwise it is a decision on the effect of speed-escaping interference. Range of estimates of the differences Δ^{^}F^ν_ai(k) and Δ^{^}F^R_ai(k) is broken down into Q nonoverlapping subranges. In solving the lack of impact of escapist speed calculated interference probability P_q falling value of Δ^{^}F^ν_ai(k) in each q-th sub-band, and at the decision of the impact of noise escapist speed calculated probability P_q falling value of Δ^{^}F^R_ai(k) in each q-th sub-band. Maximum probability value is compared with the threshold value of the aircraft type recognition probability. If the threshold is exceeded, the decision to recognize the q-type aircraft with the TJE is performed with probability P_{q max}.;EFFECT: achieved technical result is possibility of recognition in pulse-Doppler radar station with probability not below specified, type of aircraft with TJE under action of speed-escaping interference.;1 cl, 5 dwg