Study and removal of power frequency interference in time-domain airborne electromagnetic data
HUANG Wei1,2,3(), XIAO Du1,2,3(), BEN Fang1,2,3, LI Jun-Feng1,2,3, LI Fei1,2,3, XU Zhi-Li1,2,3
1. Key Laboratory of Geophysical Electromagnetic Probing Technologies of Ministry of Natural Resources, Langfang 065000, China 2. Institute of Geophysical and Geochemical Exploration, Chinese Academy of Geological Sciences, Langfang 065000, China 3. State Research Center of Modern Geological Exploration Engineering Technology, Langfang 065000, China
During the flight exploration of the time-domain airborne electromagnetic system, signals are influenced by the artificial noise from high-voltage transmission lines. Consequently, the responses acquired contain power frequency interference information and thus fail to truly reflect the distribution of subsurface media. Hence, this study conducted research on the removal of power frequency interference. This study proposed a comb filter that can directly process data in the time domain, shortening the time of time-frequency and frequency-time transform, avoiding the cumbersome transform steps, and reducing the risk of possible transform errors. The key to utilizing the comb filter is to suppress the power frequency signal and its kth harmonic by means of an ideal stopband for the suppression of power frequency interference. This study developed IIR and FIR comb filters and compared their removal effects on power frequency interference with that of a single notch filter. This study aims to offer a power frequency interference removal method for the processing of time-domain airborne electromagnetic data.
Wei HUANG,Du XIAO,Fang BEN, et al. Study and removal of power frequency interference in time-domain airborne electromagnetic data[J]. Geophysical and Geochemical Exploration,
2023, 47(5): 1281-1287.
Power frequency interference noise patterns a—signal characteristics without power frequency interference;b—power frequency interference noise characteristics
The characteristic curves of notch filter at 50 Hz
The characteristic curves of FIR and IIR comb filters a—the amplitude-frequency characteristics of FIR comb filter;b—the amplitude-frequency characteristics of IIR comb filter
The signal flow diagram of IIR comb filter
The comparison of the effect of notch filter removing power-line interference
The amplitude-frequency characteristics of notch filters
The comparison of effects for FIR and IIR comb filter
The amplitude-frequency characteristics of comb filter (IIR and FIR)
The comparison of inversion before and after removing power frequency interference a—power frequency interference is not removed;b—power frequency interference has been removed
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