摘要
针对低信噪比下线性调频信号的检测问题,提出了一种简明分数阶傅里叶变换方法。该变换借助chirp相乘和傅里叶变换对时频平面上的频率轴进行旋转,以获取信号在各个角度下频率轴上的频谱分布。对时频分布呈直线状的线性调频信号,简明分数阶傅里叶变换能在特定角度上将信号能量聚集成尖锐的强能量峰,从而提高信噪比,实现对线性调频信号的可靠检测和参数估计。数值仿真和实验验证结果表明,简明分数阶傅里叶变换可对较低信噪比的线性调频信号实现有效检测,并由变换域峰值的位置对信号参数进行准确估计。相比于传统的分数阶傅里叶变换方法,简明分数阶傅里叶变换的复杂度更低,离散计算效率更高,在对噪声掩盖下的线性调频信号进行检测和参数估计时能更好地满足实时处理的要求。
The passive detection of the linear frequency-modulated （LFM） signal in low signal to noise ratio （SNR） condition is a significant problem. The concise fractional Fourier transform （CFRFT） is presented to solve this issue. The CFRFT only rotates the frequency axis in time-frequency plane to get the spectrum of the signal in different angles by chirp multiplication and Fourier transform （FT）. For the LFM signal which distributes＇ as a straight line in time- frequency plane, the CFRFT in specific angle can gather its energy as a peak value to improve the SNR, thus the LFM signal can be detected. Meanwhile, the location of the peak value relates to the parameters of the LFM signal. Numerical simulation and experimental results show that, the proposed method can detect the LFM signal masked by the noise efficiently and estimate the signal＇s parameters accurately. Compared with the conventional fractional Fourier transform （FRFT）, the CFRFT reduces the transform complexity to provide the faster computation speed. Hence, the proposed method has a better performance in real-time detection of the LFM signal.
出处
《声学学报》
EI
CSCD
北大核心
2015年第6期761-771,共11页
Acta Acustica
基金
国家自然科学基金(11434012)资助
