Power line interference attenuation in multi-channel sEMG signals: Algorithms and analysis

Abstract

Electromyogram (EMG) recordings are often corrupted by power line interference (PLI) even though the skin is prepared and well-designed instruments are used. This study focuses on the analysis of some of the recent and classical existing digital signal processing approaches have been used to attenuate, if not eliminate, the power line interference from EMG signals. A comparison of the signal to interference ratio (SIR) of the output signals is presented, for four methods: classical notch filter, spectral interpolation, adaptive noise canceller with phase locked loop (ANC-PLL) and adaptive filter, applied to simulated multichannel monopolar EMG signals with different SIR. The effect of each method on the shape of the EMG signals is also analyzed. The results show that ANC-PLL method gives the best output SIR and lowest shape distortion compared to the other methods. Classical notch filtering is the simplest method but some information might be lost as it removes both the interference and the EMG signals. Thus, it is obvious that notch filter has the lowest performance and it introduces distortion into the resulting signals.

Characterization of Forearm Muscle Activation in Duchenne Muscular Dystrophy via High-Density Electromyography: A Case Study on the Implications for Myoelectric Control

“…Additionally, a second-order digital infinite impulse response notch filter (cutoff frequency of 50 Hz, Q factor of 50) was used to remove the power line noise (50 Hz for the EU). Despite its main limitation (signal distortion around the attenuated frequency), notch filtering is the mainstream technique for powerline signal removal (26), and a narrow bandwidth with a high Q factor can already address this (27). For highly powerline-contaminated signals, spectral interpolation may be more appropriate (27).…”

“…Despite its main limitation (signal distortion around the attenuated frequency), notch filtering is the mainstream technique for powerline signal removal (26), and a narrow bandwidth with a high Q factor can already address this (27). For highly powerline-contaminated signals, spectral interpolation may be more appropriate (27). The signals were subsequently rectified and filtered with a low-pass filter (thirdorder Butterworth, 2 Hz).…”

Virtual Sensor of Surface Electromyography in a New Extensive Fault-Tolerant Classification System

“…Several solutions have been developed to reduce the interference in the acquired biomedical signals. However, a residual interference of these interferences still presents [ 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 ]. The signal contamination by motion artifacts causes data irregularities.…”

Methods of Power Line Interference Elimination in EMG Signal

“…Therefore, the filter causes the information loss. For the distortion minimization, narrow band of the filter should be used [1,3]. Fig.…”

“…The output is connected to the locked loop of the filter so that minimal output power and also a small power of the noise in output signal are obtained. For the fast optimization of the input signal weights, the RLS (Recursive Least Square) filter [14,15,16] which uses the sum of the squares of the error signal (deviation of the reference signal and the input signal) as a critical function, is used [1,3].…”