Improvement in Marine CSEM Imaging for Towed Electromagnetic Receivers through Multirate Signal Processing and Adaptive Noise Suppression

Multirate signal processing and adaptive filtering techniques have been widely employed to mitigate noise contamination and enhance the efficiency of data analysis. In towed electromagnetic (EM) receiver systems, EM motion-induced noise arising from external conductive and radiative interference and instrument vibrations caused by waves and water currents can severely degrade the quality of inversion imaging. To address this challenge, this study proposes a field-programmable-gatearray-based multirate sampling architecture integrated with a motion-related adaptive filter design that supports multistage downsampling and dynamic noise suppression. The impact of this architecture on the recovery of methane resistivity models under noisy conditions is assessed using controlled-source EM inversion analysis. The results of processing real towed electric field data contaminated with superimposed motion-induced noise demonstrate that the proposed system significantly enhances signal quality, improves imaging resolution, and reduces inversion artefacts. Compared with conventional offline processing approaches, the proposed architecture offers superior real-time capability, adaptability, and noise resistance in marine towed environments.