US 12,282,133 B2
Method and system for generating logarithmic non-uniform pseudo-random electromagnetic exploration signal
Shucai Li, Jinan (CN); Yang Yang, Jinan (CN); Jishan He, Jinan (CN); Diquan Li, Jinan (CN); Jingbo Weng, Jinan (CN); and Huaifeng Sun, Jinan (CN)
Assigned to SHANDONG UNIVERSITY, Jinan (CN); and THE CHINESE UNIVERSITY OF HONG KONG, SHENZHEN, Shenzhen (CN)
Appl. No. 17/603,442
Filed by SHANDONG UNIVERSITY, Shandong (CN); and THE CHINESE UNIVERSITY OF HONG KONG, SHENZHEN, Guangdong (CN)
PCT Filed Mar. 30, 2021, PCT No. PCT/CN2021/083728
§ 371(c)(1), (2) Date Oct. 13, 2021,
PCT Pub. No. WO2021/218525, PCT Pub. Date Nov. 4, 2021.
Claims priority of application No. 202010344576.5 (CN), filed on Apr. 27, 2020.
Prior Publication US 2022/0308249 A1, Sep. 29, 2022
Int. Cl. G01V 3/08 (2006.01)
CPC G01V 3/083 (2013.01) 12 Claims
OG exemplary drawing
 
1. A method for generating a logarithmic non-uniform pseudo-random electromagnetic exploration signal, the method comprising:
constructing two or more basic unit signals according to an exploration requirement, wherein
the basic unit signals are stairstep signals obtained by superposing a plurality of in-phase periodic square wave signals, a frequency ratio between adjacent ones of the plurality of periodic square wave signals is 2, and the two or more basic unit signals meet the following requirements: if a lowest frequency of dominant frequencies in a first basic unit signal is denoted as a fundamental frequency, lowest frequencies of the remaining basic unit signal are l×2m times the fundamental frequency, and the lowest frequencies of the basic unit signals differ from each other, wherein l is an odd number except 1, and m is a natural number; and
superposing the two or more basic unit signals to obtain superposed stairstep signals, and correcting amplitudes to be consistent with amplitudes of the periodic square wave signals, to obtain a logarithmic non-uniform 2n sequence pseudo-random signal;
wherein, the logarithmic non-uniform 2n sequence pseudo-random signal comprises different frequency densities in different frequency intervals, by adjusting highest and lowest frequencies of the basic unit signals and controlling of a multiple between the lowest frequencies of dominant frequencies in the basic unit signals to be l×2m;
performing a geophysical field exploration by using the logarithmic non-uniform 2n sequence pseudo-random signal, continuously receiving electromagnetic information and field data focused in frequency intervals of interest to prospectors by receivers in a rolling manner; wherein, the logarithmic non-uniform 2n sequence pseudo-random signal is able to be simultaneously transmitted and received at dozens of frequencies; and
determining at least one physical characteristic of an underground subject to the geophysical field exploration by analyzing the logarithmic non-uniform 2n sequence pseudo-random signal.