METHOD OF AIRCRAFT WITH TURBOJET ENGINE TYPE IDENTIFICATION IN PULSE-DOPPLER RADAR STATION Russian patent published in 2020 - IPC G01S13/52 

FIELD: radar ranging.

SUBSTANCE: method consists in that a radar signal reflected from an aircraft with TJE is subjected to narrow-band Doppler filtration based on a fast Fourier transform (FFT) procedure and converted into amplitude-frequency spectrum (AFS) of signal reflections from aircraft airframe with TJE and rotary blades of impeller of low-pressure compressor (LPC) of its power plant. By threshold processing of AFS signal only those samples of Doppler frequencies F_i with corresponding amplitudes of spectral components are formed, which have exceeded the set threshold. Simultaneously, during time T of each space survey, two distance values D₁ and D₂ are measured for an aircraft with TJE and a frequency position of Doppler frequency F_p is determined, which depends on speed of approach of a pulse-Doppler carrier with an airframe of an aircraft with TJE. Determining, in the AFS signal, the Doppler frequency position with the spectral component with maximum amplitude exceeding the preset threshold, which corresponds to Doppler frequency F_k, determined by speed of approach of pulse-Doppler carrier with rotating blades of LPC first stage of power plant of aircraft with TJE, and calculating difference of Doppler frequencies ΔF_pk=(F_p-F_k). In addition, during time T of each space survey, values of bead bearings are measured ϕ_g azimuth and ϕ_v elevation angle, average range, calculate flight altitude of aircraft with TJE. For each aircraft with TJE flight altitude H, the difference range ΔF_pk are divided into Q non-overlapping subranges. When difference of Doppler frequencies hits ΔF_pk to the q-th sub-range decide on the q-th type of aircraft with TJE flying at the height H.

EFFECT: high reliability of identifying the type of aircraft with a turbojet engine in a pulse-Doppler radar during flight at different altitudes.

1 cl, 4 dwg