Magnetotelluric time domain calibration method and system

Abstract

The invention discloses a magnetotelluric time domain calibration method and system. The method comprises the following steps: 1, ; the method comprises the following steps: acquiring a system response of a time sequence in the magnetotelluric depth finder, an amplitude correction value of each frequency and a phase correction value of each frequency; determining a calibrated transfer function according to the amplitude correction value and the phase correction value, determining a calibrated unit impulse response function by adopting an inverse Fourier transform method according to the calibrated transfer function, and determining a complex sequence of system response by adopting a Hilbert transform method; and performing convolution operation on the unit impulse response function and thecomplex sequence to obtain a calibrated time sequence. By adopting the method and the system provided by the invention, the time sequence can be directly calibrated, and the method and the system have the advantages of reducing the loss of effective signals and the residue of noise caused by filtering and enhancing the robustness of a time domain impedance estimation result.

Description

technical field [0001] The invention relates to the technical field of electromagnetic prospecting, in particular to a magnetotelluric time domain calibration method and system. Background technique [0002] Magnetotelluric sounding is an important method in electromagnetic exploration. This method realizes the inversion of underground electrical structure by observing the orthogonal electromagnetic components in the natural magnetotelluric field. However, the signal strength of the natural electromagnetic field is weak, and the signal energy is not uniformly distributed with frequency. Therefore, the magnetotelluric sounding system will perform frequency division gain on the measured electromagnetic field signal. At the same time, in order to suppress the impact of environmental noise and according to the requirements of the instrument for the measurement frequency range, various filters are installed inside the instrument. Most of these filters are not zero-phase filters,...

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Problems solved by technology

However, when this method is used to process the time series with system influence, because the system has different influence on the circuit and the magnetic track, this influence cannot be offset when performing impedance estimation, but will continue to accumulate with recursion, Ultimately, the current time-domain impedance estimation results have large error bars at the middle frequency point and serious tail branch dispersion, which affects the processing effect of the method.

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