Abstract
Micro-motion parameters extraction is crucial in recognizing ballistic missiles with a wideband radar. It is known that the phase-derived range (PDR) method can provide a sub-wavelength level accuracy. However, it is sensitive and unstable when the signal-to-noise ratio (SNR) is low. In this paper, an improved PDR method is proposed to reduce the impacts of low SNRs. First, the high range resolution profile (HRRP) is divided into a series of segments so that each segment contains a single scattering point. Then, the peak values of each segment are viewed as non-stationary signals, which are further decomposed into a series of intrinsic mode functions (IMFs) with different energy, using the ensemble empirical mode decomposition with the complementary adaptive noise (EEMDCAN) method. In the EEMDCAN decomposition, positive and negative adaptive noise pairs are added to each IMF layer to effectively eliminate the mode-mixing phenomenon that exists in the original empirical mode decomposition (EMD) method. An energy threshold is designed to select proper IMFs to reconstruct the envelop for high estimation accuracy and low noise effects. Finally, the least-square algorithm is used to do the ambiguous phases unwrapping to obtain the micro-curve, which can be further used to estimate the micro-motion parameters of the warhead. Simulation results show that the proposed method performs well with SNR at −5 dB with an accuracy level of sub-wavelength.
Highlights
In the missile defense system, it is crucial to distinguish the true warheads from decoys in the mid-course phase, where warheads and decoys exhibit different micromotions
The warhead is usually considered as a whole, and many methods based on the whole radar cross section (RCS) are developed [13,14,15]
The proposed method can adaptively estimate the envelop according to the characteristics of the signal
Summary
In the missile defense system, it is crucial to distinguish the true warheads from decoys in the mid-course phase, where warheads and decoys exhibit different micromotions. In the past few decades, many methods have been developed to exploit the micromotion features to recognize the mid-course ballistic missiles [7,8,9,10,11,12] It is difficult for the narrow-band radar to discriminate the different scattering points lying on the true warhead due to its low range resolution. In [17], the authors proposed a new PDR method to extract Doppler phases from HRRP sequences through a matched filter This algorithm was developed in [7], where they applied the same method to the direct sampling linear frequency modulated signal to avoid the influences of the recording error. We develop an improved PDR method and attempt to deal with the micro-motion parameters extraction in the wideband radar.
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