分数阶傅里叶变换较之于传统傅里叶变换能更有效地将线性调频信号与噪声分离.但分数阶傅里叶域频谱能量的聚集性受信号占空比及调频带宽两方面影响,当占空比较小并且调频带宽很宽时,往往难以得到尖锐的谱峰.本文提出短时滑窗方式的分数阶傅里叶滤波方法,分析了时频域截断对其频谱的影响,在此基础上提供一种低信噪比情况下线性调频信号的检测准则,进而详细论述分数阶傅里叶域滤波的流程.仿真结果表明,运用这种准流水方式的滤波方法处理盲信号,信噪比可提高10dB以上,而有用信号的能量损失却极小.在雷达的欺骗干扰领域应用此方法可提高干扰性能.%The LFM signal and noise could be separated more effectively by FRFT than by traditional FFT. The energy gathering of FRFT spectrum is effected by duty ratio and FM bandwidth. With small duty ratio and wide FM bandwidth, the spectrum peak of FRFT would not be very sharp. The article presents a new slipping window way used in fractional Fourier filtering of LFM signal. The effect of time and frequency intercept in FRFT is also analyzed. A differentiation principle used in LFM signal detection under the condition of low SNR is provided based on the analysis before. Also, the filtering process in fractional Fourier domain is discussed in detail. It is indicated by the emulation result that blind signal could be processed by the filtering way in pipelining mode with little noise energy. The SNR could increase more than 10dB. It also indicates that the effect is improved in radar deception jamming domain.
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