Abstract :
Vibrating targets cause phase modulation of the azimuth phase history for a SAR system. The phase modulation may be seen as a time-dependent micro-Doppler frequency. It is useful to analyse such signals with Cohen´s (1995) class time-frequency methods due to their superior resolution potential. The method must be chosen with care, as the effective time integration window of the kernel should not be longer than about a cycle of the modulation signal. Using the adaptive optimal kernel method (AOK), the authors obtained good results from a controlled experiment where two oscillating corner reflectors were placed within a SAR scene collected by the US Navy APY-6 radar. The oscillation frequency and amplitude were calculated from the time-frequency distributions and the results agree well with available ground truth. To resolve the instantaneous frequencies, the kernel time extent had to be sufficiently short
Keywords :
Doppler effect <vibr. targets, SAR, Micro-Doppler anal.>; adaptive signal processing <vibr. targets, SAR, Micro-Doppler anal.>; image resolution <vibr. targets, SAR, Micro-Doppler anal.>; radar imaging <vibr. targets, SAR, Micro-Doppler anal.>; radar resolution <vibr. targets, SAR, Micro-Doppler anal.>; synthetic aperture radar <vibr. targets, SAR, Micro-Doppler anal.>; time-frequency analysis <vibr. targets, SAR, Micro-Doppler anal.>; Cohen´s class time-frequency methods; SAR system; US Navy APY-6 radar; adaptive optimal kernel method; azimuth phase history; ground truth; high-resolution images; micro-Doppler analysis; modulation signal; oscillating corner reflectors; oscillation amplitude; oscillation frequency; phase modulation; signal resolution; synthetic aperture radar; time integration window; time-dependent micro-Doppler frequency; time-frequency distributions; vibrating targets;
