Research on filtering of electromagnetic measurement while drilling signal in underground coal mine
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摘要: 针对采用自适应滤波最小均方算法和递推最小二乘算法提取煤矿井下电磁无线随钻测量(EM-MWD)信号存在收敛速度慢与运算时间长等问题,提出了一种稳定快速横向递归最小二乘 (SFT-RLS)算法,用于自适应滤除井下非稳态电气干扰与工频及其2倍频、3倍频干扰,实时提取微弱EM-MWD信号。该算法基于RLS算法,利用4个并行滤波器结构可降低运算时间,并利用加权最小二乘误差进行反馈以提高稳定性。仿真试验结果表明,SFT-RLS 算法可实现对采样率为1 kHz的EM-MWD信号进行自适应滤波和自适应陷波,平均每次迭代运行时间小于156.98 μs,实现了快速稳定收敛运算与实时自适应滤波;SFT-RLS算法自适应滤波可抑制信号与干扰比为-115 dB的非稳态电气干扰;SFT-RLS算法自适应陷波可实时滤除工频及其2倍频、3倍频干扰,有效提取频率为6.25 Hz的时间脉冲位置调制的EM-MWD信号波形,为正确解码EM-MWD信号提供了可靠数据。
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关键词:
- 煤矿井下电磁无线随钻测量信号 /
- 非稳态干扰 /
- 工频干扰 /
- 自适应滤波器 /
- 自适应滤波 /
- 自适应陷波 /
- 稳定快速横向递归最小二乘算法
Abstract: In view of problems of slow convergence speed and long computation time existed in electromagnetic wireless measurement while drilling (EM-MWD) signals extracted by adaptive filtering least mean square algorithm and recursive least squares algorithm, a stabilized fast transversal filters for recursive least squares (SFT-RLS) algorithm was proposed, which was used for adaptive filtering unsteady electrical interference and power frequency, as well as double frequency and triple frequency interference, and extracting weak EM-MWD signals in real time. Based on the RLS algorithm, the algorithm uses four parallel filter structures to reduce the operation time, and uses the weighted least squares error for feedback to improve the stability. The simulation results show that the SFT-RLS algorithm can achieve adaptive filtering and adaptive notch of the EM-MWD signals with a sampling rate of 1 kHz, the average running time of each iteration is less than 156.98 μs, so as to realize fast and stable convergence operation and real-time adaptive filtering of EM-MWD signals; the adaptive filtering of the SFT-RLS algorithm can suppress unsteady electrical interference with a signal to interference ratio of -115 dB; the adaptive notch of the SFT-RLS algorithm can filter power frequency and its interference of double frequency and triple frequency in real time, and effectively extract the EM-MWD time position pulse modulation signal with 6.25 Hz, and provide reliable data for correct decoding of EM-MWD signals.
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