Abstract:

In the over-the-horizon radar (OTHR), the Doppler spread in the maneuvering target echo reduces the detection performance. The strong sea clutter further increases the detection difficulty. Considering that the sea clutter is mainly near zero frequency and can be modeled as an auto-regressive (AR) process, an AR filter has been used to suppress the sea clutter. Considering that fractional Fourier transform (FRFT) can effectively concentrate chirp signals, and the maneuvering target signal is approximately a chirp signal, the FRFT-based method has been applied in the maneuvering target detection and parameter estimation. The grading iterative method is used for fast calculation, and the shading problem between multiple targets is solved through the “CLEAN” method. The proposed algorithm can be better applicable to multitarget detection compared with the discrete polynomial transform (DPT) method, and has higher parameter estimation accuracy than the RadonWigner transform (RWT) method. Simulation results show that the proposed algorithm improves the maneuvering detection ability of OTHR, and can estimate the parameter of the target more accurately.