Implementation Of Electromagnetic Prospecting Digital Filter And Design

The main method of geophysical exploration has magnetotelluric sounding (MT) and controlled source audio magnetotelluric (CSAMT), as well as the rest of the frequency domain electromagnetic method, which is a effective way of metal mineral exploration, petroleum exploration, geothermal research, deep Earth physical exploration. However, because electromagnetic waves of electromagnetic exploration have electromagnetic waves field characteristics, and also because of the limitations of the data processing, making the ability to distinguish the signal drop, in practical work, how to make the MT or CSAMT can be widely used becomes a problem. For electromagnetic exploration method, to get a valid signal and complete a high-quality processing of data is an important part of treatment for obtaining the useful electromagnetic response function. According to the characteristics of the raw data collected of the electromagnetic exploration and the data in line with standard getting after a deal, this paper presents the application of FIR digital filter technology of electromagnetic exploration to suppress noise in time domain sequence and obtain effective signal processing.Electromagnetic signal of this paper using the Fourier transform of to Calculate power spectrum, in order to obtain the frequency characteristic of the effective signal and an interference signal, according to the transmission frequency characteristic of the practical work of the electromagnetic detection method, and the electromagnetic frequency sampling rate, setting performance of the filter, studying FIR filter algorithm to be complete the set performance and with high efficiency.For the characteristic of method CSAMT, each acquisition a frequency information, this paper propose a new method for removing the interference, by adding a band-pass filter whose factor can be reset in acquisition device, to filter out all the signals beyond the point of the collected frequency, and compute and generate by FPGA hardware, to achieve the multiplexing of the filter kernel,save FPGA resource consumption, improve the flexibility and application range of the filter.By software simulation experiments and practical work CSAMT filtering analysis of data collected, the results showed that the coefficient resettable bandpass filter has a positive effect in CSAMT method, through the narrowband signal acquisition, interference filter beyond the signal band can be completed, weakening the out-band noise in front of the collected data, and working to solve the problem of frequency interference, improving the quality of data on the source signal acquisition, providing a strong guarantee for subsequent data inversion.