基于FRFT的宽带水下动目标的速度估计

Moving Target Velocity Estimation in Underwater Wideband Using FRFT

宽带系统中发射信号为线性调频信号时,根据其窄带模糊度函数脊线为直线而运用解藕原理估计目标速度的性能将急剧下降。目标速度引起信号的尺度伸缩,回波信号依然是线性调频信号。由于分数阶傅立叶变换对线性调频信号的聚焦特性和变换的尺度特性,提出了基于分数阶傅立叶变换估计目标的径向运动速度方法,推导了目标运动速度和分数阶傅立叶变换阶数之间的关系并分析了阶数对速度估计的影响。最后进行了数值仿真,结果表明该估计方法可以有效地估计高速目标的速度,并且具有较高的估计精度。

When the transmitted signal is linear frequency modulation（LFM） signal,the performance of velocity estimation based on narrow ambiguity function is degraded in wideband system.Because target velocity will caused scaled version signal,the echo is still a LFM signal.And the LFM energy in Fractional Fourier Transform Domain can be centered.Then the velocity estimation method based on the scale properties of Fractional Fourier Transform was proposed.The relationship between the order of FRFT and target velocity was derived and the effect of the order on estimated velocity was analyzed.At last,the numerical simulation shows that the proposed method can estimate the velocity of high speed target and has higher accuracy.