Design And Implementation Of EGD Dialing System Based On Visual C++

Brain-computer interface (BCI) system is a communication system which can exchangeinformation with the outside world without relying on the peripheral nervous system and muscletissue. It collects the Electroencephalogram (EEG) at the cerebral cortex and then converts thedecoded information into control commands to control external devices directly.Steady-state visual evoked potential (SSVEP) and spontaneous EEG Alpha waves are oftenserved as the input signals of the BCI system, because both of them have higher SNR (Signal toNoise Ratio), higher information transfer rate and obvious detective features while neither ofthem requires specific training. This thesis designs an electrical dialing system based on tencontrol commands generated from SSVEP signals and another two generated by interdicting theclosed-eyes Alpha waves. The content mainly includes the following four parts: visual stimulatordesign, signal processing algorithm, the construction of the PC software experiment platform andperipheral circuit module.(1) Completes the high precision LED visual stimulation design based on AVRmicrocontroller. Based on the mechanism of SSVEP and the number of control commands whichthe dialing system needs, to design control interface and write control procedures for stimulatorby choosing, assembling and debugging the appropriate stimulus frequency and control chip. Theexperiment not only proves that the stimulator is meeting the system requirements and has astable performance but also provides a solid base for the further research.(2) Completes the on-line signal processing of EEG data by taking appropriate algorithm.Adopting power spectrum estimation and Hilbert Huang Transform (HHT) to extract SSVEPpotential and identify frequency, the experiments show that both algorithms are capable ofreal-time processing but HHT is more accurate and less time-consuming.(3) Designs and constructs the PC platform with VC programming software in the Windowsenvironment which mainly consists of EEG acquisition, signal processing, human-machineinterface and serial communication, all of these will promote the brain-computer interfacetechnology be applied in real life.(4) Microprocessor controls GSM wireless communication module TC35and thus comesout the communication module. By controlling the serial communication of the MCU to receivethe command of EEG signals of upper computer, and processing the dialing instructions whichcorrespond to the AT command table, and then sending the commands to the communicationmodule to achieve the EEG mobile phone dialing and voice calling functions.