Vibration estimation in SAR images using azimuth time-frequency tracking and a matched signal transform

This paper proposes a vibration-induced micro-Doppler estimation method for oscillating targets in synthetic aperture radar (SAR) images using azimuth time-frequency tracking and a matched signal transform. The approach involves an azimuth defocusing of the SAR image in order to access the phase history. The tracking in azimuth is based on local polynomial phase modeling using as estimator for the polynomial coefficients the high-order ambiguity function. The vibration frequency is obtained from the spectrum of the tracked instantaneous frequency law, while the oscillation amplitude is estimated using a matched signal transform. The procedure is tested by simulations and on real SAR images acquired by the TerraSAR-X satellite over the Puylaurent water-dam in France.