The Digital Acquisition Terminal Of EEG Amplifer Design

In recent years, EEG acquisition system has been received wide attention of researchers and clinicians and it has become the instrument of scientific research hotspot. The performance of the system determines whether can obtain a wealth of information on brain activity. In order to improve the overall performance of the original EEG amplifier digital acquisition end,we redesigned the EEG amplifier digital acquisition terminal.The design use high precision, high resolution, 24 bit analog to digital converter AD7731 to complete analog to digital conversion. DSP is used to control the operation of the whole system and receive the data after AD conversion and sent to the USB controller. The EEG data is sent to PC by USB2.0 interface. In the host computer we use VC++ to compile collection procedures, realize the storage and analysis of EEG data.In order to verify the performance of the EEG signal acquisition system, firstly we test the data transmission rate of the system, the value of it is up to 60 Mbps. Secondly we do the simulated signal testing, and the results show that the system can accurately collect the simulation signal. Thirdly we analysis and compare the difference of the EEG data when the subjects are in the opening eyes state and in the closed eyes state respectively, and we find that only the power spectral density map can be seen obviously alpha wave component; We also analysis EEG data on SSVEP power spectrum density, and the analysis results can be obviously observed the brain evoked potential. The testing results show that the digital acquisition terminal of EEG amplifer has good performance, can be used to study brain function.