基于分数阶傅里叶变换的水下目标速度估计

Underwater Target Velocity Estimation Based on Fractional Fourier Transform

摘要:

在高斯白噪声背景下,匹配滤波器作为线性调频信号的最优检测器,在水声信号处理中被广泛应用。 当发射信号为线性调频信号时,由水下目标径向速度引起的多普勒频移会造成回波和样本之间失配, 使匹配滤波器的检测性能下降,增加了目标速度估计的难度。 利用分数阶傅里叶变换对于线性调频信号的聚焦特性,提出了应用分数阶傅里叶变换的水下运动目标线性调频回波检测算法,完成对目标速度的估计, 推导目标运动速度与分数阶傅里叶变换阶数之间的关系,并对测量结果进行误差分析。 仿真测试表明,该算法可有效地估计混响背景下的目标径向速度,且具有良好的估计性能。

Abstract:

Under white Gaussian noise background, matched filters are the best detectors for LFM signals and are widely used in underwater acoustic signal processing. When the transmitted signal is a LFM signal, the Doppler shift caused by the radial velocity of the underwater target will cause a mismatch between the echo and the sample, which will degrade the detection perform- ance of the matched filter and increase the difficulty of estimating the target velocity. Using the FRFT to focus on the LFM signal, an underwater moving target LFM echo detection algorithm using FRFT is proposed to estimate the target velocity and derive the re- lationship between the target motion velocity and fractional Fourier transform order, and perform error analysis on the measurement results. Simulation tests show that the proposed algorithm can effectively estimate the target radial velocity in the reverberation back- ground and has good estimation performance.