The Development Of A Digital EEG System Based On DSP

Electroencephalograph (EEG) is an important means in researching functional activities of human brain, and has high value for clinical diagnosis. But acquisition of EEG signal is not very easy, for the signal is so weak and often contaminated by strong background noises. The analog filter is usually used in the traditional EEG collecting system to eliminate these noises, but this method is not very flexible and sometime can't do well. In order to get the quality EEG waves, the software filter must be used in PC, but in this way, the system is not working in real-time.To solve this problem, a digital signal processing module is considered to add in the traditional EEG system and realizes digital filter. The primary-auxiliary structure is used in system design. MCU as the primary chip completes the general control tasks of the system, while the DSP as the auxiliary chip implements EEG filter algorithm. The hardware of the whole system involves pre-amplifier, filter amplifier, multi-channel switch, A/D converter, MCU, DSP and USB module.The research works of this paper mainly focus on the design of DSP module. In the facet of hardware, TMS320VC5416 chip is chosen and the design of peripheral circuit is completed. The HPI (Host Port Interface) which is special for C54X DSP is responsible for communicating with MCU and a Flash is expended to make system booting by itself. In the facet of software, the real-time of the system and linear phase of EEG signal processing are well considered. Firstly, an adaptive coherent model algorithm is used for filtering both power line interference and baseline wander. And then, the FIR filter is used for getting the ideal bandwidth and gain of the signal. The software development is under the CCS platform.Comparing with traditional method, this system can get quality EEG waves by using real-time and line phase digital filter, and the flexility and stability of the system are also improved.