Research On LMT Signal Denoising Based On Mathematical Morphology

Since the advent of magnetotelluric sounding method,it has been applied in more and more fields because of its advantages such as simple method,convenient implementation and remarkable effect.The research on the method of magnetotelluric signal noise separation has become a hot and difficult problem in the field of signal analysis,Because of its weak signal energy,wide frequency range and easy to be interfered,the special long period magnetotelluric signal becomes a difficult problem of signal noise separation,Therefore,the long period magnetotelluric signals collected in the field need to be denoised before they can be used reliably.At present,there are a lot of methods for long period magnetotelluric signal denoising,such as wavelet transform,windowed Fourier transform,source reference method and so on.Many research results have been achieved,but the current methods have some defects,and most of them are based on frequency domain denoising.Therefore more to adapt the processing method of long period magnetotelluric signal is always a hotspot in the field of magnetotelluric sounding,this paper based on this background,put forward the principle of mathematical morphology for long period magnetotelluric signal processing.In this paper,the difference between the mathematical morphology method and the previous method of long period magnetotelluric signal processing is that the mathematical morphology denoising is based on the time domain processing,The method is suitable for the wide frequency range of the magnetotelluric signal,and the method has a solid mathematical foundation,a simple principle and a large space for development.The simulation results show that this method is very effective.The main contents of this paper are as follows:(1)This paper summarizes the field source of magnetotelluric signal,and analyzes various kinds of noise interference.The different effects of each noise on the magnetotelluric signal are analyzed.It is pointed out that the data exists in long period magnetotelluric data.(2)This paper briefly introduces the classification of signals and the general methods of signal processing.The characteristics of different signals are also briefly described,and the typical algorithms of the signal analysis methods are introduced.At the same time introduced the signal spectrum,amplitude and other characteristics.(3)In this paper,the basic mathematical theory of morphology is introduced,and the definition and mathematical meaning of four basic operators in morphological filtering are described in detail.The filtering effects of the four basic operators are simulated by experiments,and their specific denoising performance is discussed.Simulation and comparison of the traditional several structural elements of the denoising performance,and the definition of structural elements to signal processing.(4)Based on the theory of mathematical morphology filter,the long period magnetotelluric measurement signal is denoised.This paper analyzes the effect of different types of structural elements on the denoising of long period magnetotelluric.On the basis of mathematical morphology denoising and median filtering,the long period magnetotelluric signal is processed.The experimental results show that the method is effective.(5)At last,the method of mathematical morphology and the wavelet packet denoising method in the field of denoising are used to deal with the same signal.The experimental results show that the method proposed in this paper is better than the wavelet packet denoising method.