【摘要】 埋地金属管道铺设环境错综复杂，在管道定位过程中，接收机需要从管道辐射的多频信号中有效分离出128 Hz定位信号，滤除高频信号和50 Hz工频信号。针对埋地管道检测的现实需求，设计了9种不同类型和拓扑结构的四阶128 Hz窄带通滤波器，并通过Multisim14进行仿真分析。结果表明，同种拓扑结构不同电路结构的滤波器幅频特性曲线相同，输入输出增益稍有不同。这9种滤波器的中心频率均在128 Hz附近，其中1 dB切比雪夫型MFB滤波器带宽最窄，为36.803 Hz,Q值最大，为3.473。进一步分析表明，1 dB切比雪夫型MFB滤波器能够有效提取128 Hz信号并滤除干扰信号，在-3 dB带宽（108～145 Hz频率范围）内，滤波器噪声不超过0.132μV·Hz^-1/2。另外该滤波器在温度和电容容差等因素的影响下，表现出较小的幅频特性变化，具有良好的稳定性。更多还原

【Abstract】 The buried metal pipelines laying environment is complicated. During the pipeline positioning procedure, it is imperative for the receiver to effectively separate the 128 Hz positioning signal from the multi-frequency signals emitted by the pipeline, and eliminate the high-frequency signals and 50 Hz power frequency signal. According to the practical demands of buried pipeline inspection, nine types of fourth-order 128 Hz narrow-band pass filters with distinct topologies were designed and simulated using Multisim 14. The results indicate that filters of the same topology have similar amplitude-frequency characteristics, and the input-output gain is slightly different. The central frequency of the 9 filters is about 128 Hz. The 1 dB Chebyshev MFB filter has the narrowest bandwidth（36.803 Hz） and highest Q value（3.473）. Further simulation indicate that the filter can efficiently extract the 128 Hz signal and eliminate interference signals, which reduced the noise below 0.132 μV·Hz^-1/2 within the-3 dB bandwidth frequency range（i.e. 108-145 Hz）. Moreover, the filter demonstrates strong stability and shows slight variations in amplitude-frequency characteristics when subjected to changes in temperature and capacitance tolerance.更多还原