基于改进小波阈值去噪的地下管线磁异常信号提取研究

Research on magnetic anomaly signal extraction of underground pipelines based on improved wavelet threshold denoising

为解决地下管道磁异常信号采集受环境噪声干扰的问题,本文采用小波阈值法作为地下管道磁异常信号的基本去噪模型,并加入复合归一化指标。在传统评价指标的基础上,优化小波基函数、最优分解尺度和阈值函数,确定具有可调变量基因的改进阈值函数,以弥补传统软硬阈值函数估计方法的断点振荡和丢失细节的不足。通过仿真信号和实验,对含噪磁异常信号进行去噪及效果评价。仿真和实验结果表明,改进后的阈值函数能有效消除周围噪声对磁异常信号的干扰,进而准确恢复原始磁异常信号,与常规方法相比,提取的信号失真较小,信噪比较高,可为后续的磁异常反演提供更准确的数据支持。

The collection of magnetic anomaly signal underground pipelines is disturbed by environmental noise.The wavelet threshold method is used as the basic denoising model of the magnetic anomaly signal of underground pipelines,and a composite normalization index is added on the basis of the traditional evaluation index to optimize the wavelet basis functions,optimal decomposition scale and threshold function.An improved threshold function with tunable variable genes is determined to make up for the lack of breakpoint oscillations and loss details of traditional soft and hard threshold function estimation methods.The denoising and effect evaluation of the noisy magnetic anomaly signal is carried out through the simulation signal and experiment.The simulation and experimental results show that the improved threshold function can effectively eliminate the interference of the surrounding noise on the magnetic anomaly signal,and then accurately restore the original magnetic anomaly signal compared with conventional methods,the extracted signal has less distortion and higher SNR,which can provide more accurate data support for subsequent magnetic anomaly inversion.