Modulation effect and inverse synthetic aperture radar imaging of rotationally symmetric ballistic targets with precession

The modulation effect of rotationally symmetric ballistic targets (BTs) with precession is concerned. To further approach the actual case, the modulation in amplitude and Doppler is considered in the radar backscattering and revealed by short-time Fourier transform (STFT). The results indicate that the micro-Doppler (m-D) effect induced by periodical precession is not represented as a sinusoidal modulation on the edge of BTs as usual, and the amplitude modulation may lead to discontinuity of time-frequency curve. The phenomenon in STFT is confirmed by both simulated and real data from a BT model with precession measured in the microwave anechoic chamber. Based upon the measured data, inverse synthetic aperture radar imaging results have been obtained by smoothed pseudo Wigner-Ville time-frequency distribution.