Research On Seismic Signal Acquisition And Noise Reduction Method

The acquisition of seismic signals is an important step for researchers in the study of seismic information monitoring and prediction,stratigraphic inversion,etc.The performance of the seismic signal acquisition system directly affects the quality of the acquired signal,High precision and large dynamics are the research directions of seismic data acquisition systems.Due to the influence of the geographic environment of the seismic monitoring station and other factors,the seismic acquisition signal contains a lot of noise,which affects the recognition of seismic signals by seismic workers,and even misjudgments and false alarms occur.The noise reduction processing of seismic signals is also critical.Based on the above two aspects,this article mainly carried out the following research work:(1)Designed a 24-bit high-precision,large-dynamic seismic signal acquisition system,which mainly includes signal conditioning unit,A/D conversion unit,digital filter unit,microprocessor unit,SD card data storage unit,GPS timing unit and host computer communication hardware Module.Complete data collection,SD card storage,host computer communication and GPS timing driver design.A signal acquisition test was performed on the acquisition system,and the effective value of the system’s selfnoise was 0.0015 m V,and the dynamic range was 124.5 d B.(2)Aiming at the problem that the traditional wavelet modulus maximum method has a single threshold and cannot completely remove noise on small scales,a wavelet maximum modulus(ATWMM)noise reduction algorithm based on adaptive threshold is proposed.By setting a function that automatically adjusts the threshold as the decomposition scale changes,small-scale noise is removed.After single-channel Ricker wavelet denoising experiment analysis,compared with the traditional wavelet modulus maximum denoising algorithm,the signal-to-noise ratio increased to18.8587 d B after processing by the ATWMM algorithm,which was an increase of11.23%;the root mean square error was reduced to 0.2968,which was reduced Up20.11%;Carry out 30-channel Ricker wavelet synthesis seismic profile noise reduction experiment analysis,under different noise levels of-10 d B,-5 d B,-3 d B,3 d B,and 5d B,compared with the traditional algorithm,after ATWMM algorithm processing,the signal-to-noise ratio can be increased by more than 8%,and the root mean square error can be reduced by more than 10%;In 2017,Jiuzhaigou 51 JZW station monitoring threeway aftershock signal noise reduction experiment analysis,compared with the traditional algorithm,the signal-to-noise ratio of the NS,EW,and UD three-way signals after processing by the ATWMM algorithm increased to 31.9519 d B,31.9083 d B,30.1855 d B,respectively,An average increase of 19%.Experimental results show that the ATWMM algorithm has a better noise reduction effect than the traditional modulus maximum algorithm after setting the function that automatically adjusts the threshold value with the change of the wavelet decomposition scale.