The Doppler spectrum modeling of the sea clutter is of great significance for using the Doppler radar to suppress the sea clutter and detect the target on sea surface. Taking into account the characteristics of the Doppler spectrum components corresponding to three scattering mechanisms, the Bragg, whitecap, and breaking-wave, we propose a time-varying Doppler spectrum model of radar sea clutter in this paper. The Doppler spectrum shifts and bandwidths of the three scattering mechanisms are considered respectively, and a Doppler shift of an added wave speed is introduced into this model. Because the spectrum intensity is defined as a random variable being a function of the measuring time of the sea clutter series, the model has the ability to model both the long-time averaged Doppler spectra and the short-time Doppler spectra. By modeling the short-time Doppler spectra and the long-time averaged Doppler spectra of the shore-based radar sea clutter measured in the China Yellow Sea at P and S bands, it is indicated that the proposed model has a higher precision than the conventional model, and especially, the modeling errors decrease significantly in the cases of the short-time Doppler spectra with long measuring time and the long-time averaged Doppler spectra with complex shapes.%海杂波的多普勒谱建模对采用多普勒处理技术的雷达进行有效的海杂波抑制和目标检测具有重要的意义.本文分别考虑Bragg,白冠和破碎波三种散射机制对应的多普勒谱分量的特征,对三种谱分量的频移和展宽进行分离,并引入附加速度频移量,提出了基于不同散射机制特征的雷达海杂波时变多普勒谱模型.该模型假设谱强度为受观测时间区间影响的随机变量,能够同时适用于平均多普勒谱与短时多普勒谱建模.通过分别对黄海海域实测的岸基P,S波段海杂波平均多普勒谱与短时多普勒谱建模测试,结果表明该模型相对传统模型的建模精度更高,尤其体现在短时谱的观测时间较长和平均谱形式较为复杂的情况下,建模误差显著减小.
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