Table 9.

Various artefacts in EEG signal recording

Category	Artefact /Source(Cause)/Frequency/Amplitude Morphology	Artefact Prevention
Physiological Artefacts	Cardiac/Heart/$\le$1Hz/1-10mV /Epilepsy	Selection of proper montage Monitoring during recording Offline visual inspection Low pass filter (LPF) Data Rejection
	EOG/Eye/0.5-3 Hz/100mV /Tumour, delta wave	Artefact-free recording protocol Online monitoring Offline visual inspection Low pass filter (LPF) Using various Transform (ICA, PCA, EOG subtraction)
	Muscle Artefact/Muscle /$\ge$ 100Hz/low /Beta frequency	Artefact-free recording protocol Online Monitoring Offline visual inspection High pass filter(HPF) Data rejection
	Physical movement artefact /Physical movement /Very low/ very high /Morphology different from actual EEG	Artefact-free recording protocol Online monitoring Offline visual inspection Data rejection
External Artefacts	Transmission line /Transmission line 50–60 Hz/low/ Morphology different from actual EEG	Notch filter DC power supply
	Phone artefacts /Mobile and landline phone /high/high/different	Artefact-free recording protocol
	Electrode artefact /Electrode and sweating /very low/high	Artefact-free recording protocol LPF
	Impedance artefact /Electrode with impedance>5K$\mathrm{\Omega }$ /-/approximately 100 μV/different