Analysis of phase coding SSVEP based on canonical correlation analysis (CCA)

Steady-state visual evoked potential (SSVEP) has been widely applied in brain computer interface (BCI) systems. The amplitude and phase features of SSVEP were commonly extracted by Fourier analysis method from single-channel EEG data. In the multichannel case, canonical correlation analysis (CCA) has been utilized for the analysis of frequency coding SSVEP. This paper presents the analysis of phase coding SSVEP using CCA. The phase coding scheme consists of six targets flickering at 10Hz, with a 60° phase difference between any two sequential targets. For each target, 20 trials of 8s EEG signal were acquired. Using CCA, we achieve channel selection and extraction of phase features; a classification accuracy of above 80% is obtained, with the length of the time window up to 4s. The results demonstrate that phase coding SSVEP analysis based on CCA is feasible.