“…Moreover, scale invariance enables mitigation of inter‐class variability: namely, physical differences between targets of the same class (e.g. two people walking, a tall and a short one that would introduce different micro‐Doppler shift that might otherwise have led to an incorrect classification). - Speech‐inspired features [19–22], which are features initially developed for speech processing, but which have been found to be useful in classifying micro‐Doppler such as linear predictive coefficients (LPCs), cepstrum coefficients, and, especially, mel‐frequency cepstrum coefficients.
- Transform‐based features [23–25], which are typically chosen as the coefficients of a transform such as the Fourier transform, wavelet transform, and discrete cosine transform (DCT).
The efficacy of a given feature set is dependent on many parameters including transmitter frequency, range, and Doppler resolution, the aspect angle of target motion relative to the radar line‐of‐sight, and signal‐to‐noise ratio (SNR). A study of the effect of features on performance under varying operational conditions is given in [26] based on simulated micro‐Doppler signatures.…”