煤矿井下多频点视电阻率监测数椐HHT分频提取技术研究

发布时间：2018-04-09 13:31

本文选题：伪随机　切入点：监测数据　出处：《西安科技大学》2017年硕士论文

【摘要】：目前,煤矿井下电法勘探仪器主要采用单频人工场源供电,利用换频方式实现多频采集,其施工效率低、采集误差大;多频点视电阻率监测系统结合了伪随机多频信号和网络并行电法的优势,实现了信号多频点同时发射和接收,可以提高施工效率和采集精度。由于煤矿井下电磁干扰较大,发射功率受煤安限制,采集的信号比较微弱,因此监测数据的噪声干扰对视电阻率反演结果有很大影响。HHT(Hilbert-Huang-Transform,希尔伯特-黄变换)是一种处理非平稳信号的时频分析方法,在随机噪声压制和工频干扰处理等方面具有独特的优势。本文介绍了多频点视电阻率监测系统的技术原理,分析了多频伪随机发射信号的生成方法及特点,对硬件系统进行了概述;通过对采集信号的噪声频谱分析,总结了随机噪声和工频干扰的特征,采用小波分析、相关检测以及HHT方法对伪随机多频信号进行了理论数据、实验数据和试验数据的对比处理,认为HHT滤波方法可以较好地滤除工频干扰和随机噪声;对HHT方法和相关算法分别进行野外试验数据的处理,发现本文HHT提取技术对于低信噪比环境下的多频微弱信号提取具有一定的优势。研究结果表明:HHT在视电阻率监测数据的处理中可以提高信噪比,高保真地提取有用信号,尤其是在煤矿井下噪声环境复杂,信号发射功率受限的条件下,对于视电阻率监测数据的提取具有独特优势。由于HHT存在一定的模态混叠问题,影响了对噪声分辨能力,如何有效抑制模态混叠,提高滤波质量和效率,是下一步要研究的方向。
[Abstract]:At present, the electric exploration instrument in coal mine mainly uses single frequency artificial field source to supply power, and realizes multi-frequency acquisition by means of changing frequency. Its construction efficiency is low, and the acquisition error is large.The multi-frequency apparent resistivity monitoring system combines the advantages of pseudo-random multi-frequency signal and network parallel electrical method to realize the simultaneous transmission and reception of multi-frequency signals, which can improve the construction efficiency and acquisition accuracy.Because of the large electromagnetic interference in the underground coal mine, the emission power is limited by the coal safety, and the collected signal is relatively weak.Therefore, the noise interference of monitoring data has a great influence on the inversion results of apparent resistivity. Hilbert-Huang transform (Hilbert-Huang transform) is a time-frequency analysis method for processing non-stationary signals.It has unique advantages in random noise suppression and power frequency interference processing.This paper introduces the technical principle of the multi-frequency point apparent resistivity monitoring system, analyzes the generating method and characteristics of the multi-frequency pseudo-random transmission signal, summarizes the hardware system, and analyzes the noise spectrum of the collected signal.The characteristics of random noise and power frequency interference are summarized. The theoretical data, experimental data and experimental data of pseudo-random multi-frequency signal are processed by wavelet analysis, correlation detection and HHT method.It is considered that the HHT filtering method can remove the power frequency interference and random noise, and the field test data are processed by the HHT method and the related algorithms, respectively.It is found that the HHT extraction technique in this paper has some advantages for multi-frequency weak signal extraction in low SNR environment.The results show that in the processing of apparent resistivity monitoring data, the ratio of signal to noise (SNR) can be improved, and useful signals can be extracted with high fidelity, especially under the condition of complex noise environment and limited power of signal transmission.It has a unique advantage for the extraction of apparent resistivity monitoring data.Due to the existence of modal aliasing problem in HHT, the ability of noise resolution is affected. How to effectively suppress mode aliasing and improve the quality and efficiency of filtering is the next step to be studied.
【学位授予单位】：西安科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P631.3

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