以线阵CCD空间滤波效应的速度测量方法为基础，进一步提出了利用线阵CCD进行空间滤波测速(SFV)信号基频消除方法。采用异相差分检波算法，在消除基频和直流成分的同时提高了信号振幅，增加了信噪比。通过研究异相差分前后空间滤波器的功率谱密度函数，对等效差分空间滤波器的特性进行了分析。实验验证了利用异相差分检波算法进行SFV信号基频消除的可行性，结果表明，采用异相差分检波算法可以消除信号基频和直流成分，同时使周期成分的振幅加倍，有利于周期信号的提取，并解决了传统光学方法光学系统复杂，装调困难的问题。

A method of pedestal component elimination is proposed using line CCD for spatial-filter velocimetry (SFV) signal, which is based on spatial filtering effect of line CCD. By using difference demodulation arithmetic, pedestal and direct current (DC) components are eliminated, both amplitude and signal noise ratio are improved at the same time. Characteristics of equivalent difference spatial filter are analyzed with the research of power spectral density function of spatial filter difference demodulation. The feasibility of pedestal component elimination using difference demodulation arithmetic is validated with experiments. The result shows that difference demodulation arithmetic can eliminate pedestal and DC components, and amplitude of signal component is doubled, which will benefit the pick-up of useful signal component.