The line unit levelling method of airborne gamma-ray spectrum anomaly information based on wavelet filtering by layers

Airborne gamma-ray spectrometry (AGS) is a technical method that uses an aircraft as the carrier to measure airborne geophysical fields. Due to the high detection efficiency and low working cost, AGS is suitable for large-scale operations and measurements conducted jointly across land and sea. However, the accuracy is strongly associated with the detection arrangement, which may easily cause banding anomalies distributed along lines. The line unit levelling method is used to eliminate such differences occurring between the banding anomaly and mineralisation anomaly; however, artificial influence is inevitable as the parameter setting depends on experience. This paper proposes a new line unit levelling method combined with the wavelet transform theory and variation coefficient theory. This method adopts wavelet transform to perform multi-scale decomposition on the data per measurement line unit, and effectively removes non-geological background information through soft threshold filtering. The results prove that this method can significantly reduce the errors caused by time domain batches, narrow the anomaly range, and improve the recognition accuracy of ore-causing anomaly points. Moreover, the shape of the anomalies is consistent with the ground anomaly inspection results, and the distribution of radionuclides can be restored in the surveying area.