Estimation of Rotational Speed of Helicopter Rotor Through Horizontal Synchrosqueezing

This paper presents preliminary results of estimating the rotational speed of a helicopter rotor, using the short-time Fourier transform (STFT) and its concentrated form referred to as horizontal synchrosqueezing (HS) in the time-frequency (TF) domain. The presented theory is supported by real-life data obtained using a small, high-resolution radar system during a measurement campaign. The outcomes illustrated in the paper show a pronounced potential of using TF techniques in the analysis of micro-Doppler radar signals and extracting additional content from target parameters that can be used in classification and parametrization procedures. The paper shows that using the concentrated version of the spectrogram, one can distinguish more details in a non-cooperative target than the classical STFT, which in the presented research was used for assessing target parameters.