Selection of code width and analysis of influencing factors in multitransient electromagnetic method

Abstract

SUMMARYThe multitransient electromagnetic method (MTEM) uses an m pseudo-random binary sequence (PRBS) as the source waveform, which requires deconvolution to recover the impulse response. To obtain high-precision impulse responses, the frequency bandwidth of a pseudo-random sequence should be consistent with the identified system. Code width is an important parameter of an m pseudo-random sequence which determines the maximum frequency bandwidth of an m pseudo-random sequence. If the code width is too wide, the signal-to-noise ratio of the high-frequency section cannot be guaranteed; if it is too narrow, it will result in wastage of transmission time and energy. Therefore, this study developed a method for selecting an appropriate code width and an empirical formula for calculating the appropriate code width on the basis of relevant numerical simulation results. Then, factors influencing the appropriate code width were investigated through formula derivations and numerical simulations. Results showed that in the uniform half-space, the code width is proportional to the conductivity and square of offset. In the 1-D model, the appropriate code width is still proportional to the conductivity, but no longer to the square of the offset.Thank you very much for your remind.I did not refer to any data bases.