Abstract
Space target identification is key to missile defense. Micromotion, as an inherent attribute of the target, can be used as the theoretical basis for target recognition. Meanwhile, time-varying micro-Doppler (m-D) frequency shifts induce frequency modulations on the target echo, which can be referred to as the m-D effect. m-D features are widely used in space target recognition as it can reflect the physical attributes of the space targets. However, the traditional recognition method requires human participation, which often leads to misjudgment. In this paper, an intelligent recognition method for space target micromotion is proposed. First, accurate and suitable models of warhead and decoy are derived, and then the m-D formulae are offered. Moreover, we present a deep-learning (DL) model composed of a one-dimensional parallel structure and long short-term memory (LSTM). Then, we utilize this DL model to recognize time-frequency distribution (TFD) of different targets. Finally, simulations are performed to validate the effectiveness of the proposed method.
Highlights
Space target defense is a fundamental aspect in modern air defense operations [1, 2]
In [9], the scattering center is divided into localized scattering centers (LSC), distributed scattering centers (DSC), sliding-type scattering centers generated by edge diffraction (SSCE), and sliding-type scattering centers on the space target curved surface (SSCS)
We proposed a new network based on the parallel structure and long short-term memory (LSTM) units
Summary
Space target defense is a fundamental aspect in modern air defense operations [1, 2]. Many studies have been conducted on the m-D recognition of space targets by using the Cadence Velocity Diagram (CVD), time-frequency spectrograms, ISAR image, and other traditional methods. In this paper, we propose a network structure that utilizes time-frequency spectrograms to classify space targets. The target rotation axis is a straight line passing through the point O; the azimuth and elevation angles of the target coordinate system are α and β, respectively; the azimuth and elevation angles between the radar Light Of Sight (LOS) and O − XYZ are α′ and β′, respectively. According to [19], the m-D distance of each scattering point can be expressed as follows:. According to equation (4), the m-D of the sliding scattering point does not conform to the sinusoidal modulation law. The nutation m-D distance of each scattering point can be expressed as equation (4). 0 01 e m-D characteristics of SSCS do not conform to the sinusoidal modulation law
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