Helicopter classification using time-frequency analysis

Classification of Aircraft Targets With Surveillance Radars Based on Fuzzy Fractal Features

“…On basis of analyzing the performance of methods using some typical low-resolution radar target classification features [15,[24][25][26][27][28][29][30][31][32][33][34], [16] indicates that the classification method based on dispersion situations of eigenvalue spectra (CMDSES) outgoes other methods remarkably.…”

“…So far, the features extracted in methods with respect to target classification and recognition with low-resolution radars can be divided into three kinds basically: the first kind of features is extracted based on the fluctuation characteristics of return signals from targets, such as the target radar cross-section (RCS), echo amplitude undulation, echo phase undulation, echo vision effect or its 2-D gray-level map [3][4][5][6]; the second kind of features is extracted based on the target motion characteristics, for example, the motion parameters such as the flight height, velocity, acceleration, and time-spectrum (the dynamic trends that target space position as well as its motion state varies with the time is referred to as time-spectrum) [7,8]; the third kind of features is extracted based on the rotational modulation spectra (also called jet engine modulation (JEM) features), which are generated by target rotating parts, such as the rotor, empennage, propeller and turbine fan [9][10][11][12][13][14][15]. JEM features lie on the leaf number and rotary speed of the rotating parts of a target, and are independent with the target attitude if no LOS-sheltering, i.e., the rotating parts can be seen by the radar.…”

Target Classification With Low-Resolution Surveillance Radars Based on Multifractal Features

“…Currently, the research work on the extraction of JEM features is mainly concentrated on estimating the interval of adjacent spectrum lines [8][9][10][11][12][13][14][17][18][19][20][21][22][23][24][25]. However, in the conventional low-resolution radar system, the radar irradiation time towards a target is very short (often 20∼30 ms), and PRF is very low (often a few hundred ∼ a few thousand Hz), so the resolution power in the Doppler domain is lower, and the return signals from different types of aircraft targets are often overlapped in the Doppler domain.…”

“…On basis of analyzing the performance of methods using some typical low-resolution radar target classification features [17][18][19][20][21][22][23][24][25][30][31][32], ref. [3] points out that the classification method based on dispersion situations of eigenvalue spectra (abbr.…”

“…JEM) features generated by target rotating parts, such as the rotor, empennage, propeller, turbine fan, etc. [8][9][10][11][12][13][14]. JEM modulation features are determined by the leaf number and rotary speed of the rotating parts of a target and independent with the target attitude angle if no LOS-sheltering, i.e., the rotating parts can be seen by the radar.…”