Multifractal Property of Sea Clutter FRFT Spectrum for Target Detection

The paper mainly studies the multifractal property of sea clutter in the fractional Fourier transform (FRFT) domain and its application to target detection within sea clutter. According to the scale property of the mathematical definition of FRFT, the FRFT spectrum of a self-similar process in some transform order does not have uniform self-similarity at each scale. In the light of this characteristic, the multifractal theory is introduced to analyze the self-similar structure of the sea clutter FRFT spectrum and the influencing factors of the multifractal parameters in FRFT domain are studied as well. By the verification of S-band and C-band radar data, it’s shown that the sea clutter FRFT spectrum is multifractal and the generalized Hurst exponent in FRFT domain has the ability of distinguishing target from sea clutter. Based on this, the generalized Hurst exponent in FRFT domain and the bi-parameter constant-false-alarm-rate detector are combined to design target detecting method in sea clutter and the performance is analyzed as well. The results show that the proposed method performs much better than the classic fractal detecting methods in time domain.