Variable Linear Phase IIR Filter for Extraction of Track Inspection Signals
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摘要: 提出一种基于谱变换的IIR移变滤波器的设计方法,并利用分块翻转技术实现滤波器的线性相位特性.在满足提取100m范围内的长波不平顺成分的设计参数条件下,仿真计算IIR滤波器的频响误差.仿真结果表明:当翻转块长度为1600时,IIR线性相位滤波器能满足线性相位特性和幅频特性要求,比传统轨检FIR滤波器节省了95.5%的乘法运算和98.0%的加法运算,前者与后者所需的缓存量之比为9614/2135.利用实测信号计算验证了线性相位IIR移变滤波的正确性和有效性.Abstract: A design method for variable IIR (infinite impulse response) filter based on spectral transformation was presented, and time reversed section technique was utilized to achieve its linear phase characteristic.The filter was designed to conform with the specification of extracting irregularity with wavelengths within 100 m.Simulation was conducted to check the frequency response errors of the linear phase IIR filter.Simulation result shows that the filter meets the design requirements for amplitude response and linear phase characteristic when the length of reversal section is 1 600.The linear phase IIR filter requires 95.5% less multiplications and 98.0% less additions than the conventional FIR fdter, and the ratio of buffer sizes for them is 9 614/2 135.Accuracy and validity of the variable linear phase IIR filter were verified by filtering actual track inspection signals.
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