The low-cost implement of a phase coding SSVEP-Based BCI system

This paper uses the phase feature of steady-state visual evoked potential (SSVEP) to implement a brain-computer interface (BCI) system. The proposed system composes with a LED stimulation panel, a biomedical signal processed circuit, and an field-programmable gate array (FPGA)-based real-time signal processor. This design is different from the other BCI systems, which uses expensive electroencephalography (EEG) measurement equipment, personal computer, and commercial real-time signal-processing software. Besides, the proposed design uses phase feature to instead of frequency feature of SSVEP signal. The proposed system allows that users can use their brainwave to connect with external world by themselves. Implementing a prototype of the FPGA-based SSVEP BCI system verifies the effectiveness of the proposed system. The proposed system has reached an average transfer rate about 24.67 bits/min for normal subjects. Experimental results show that the subjects´ SSVEP can successfully use the proposed BCI system with high identification accuracy.