چكيده به لاتين
Abstract:
An electroencephalogram (EEG) is a device for measuring and recording the electrical activity of brain. The EEG data of signal can be used as a source of analysis for human brain function. The purpose of this study is to design a multi-channel (8 channels simultaneously) EEG system based on embedded systems. Unlike conventional methods, which initially focused on amplifying signal and then sampling it with a low resolution ADC, This project will be used with a high - resolution ADC to prevent problems arising from the amplification, such as amplifying noise and etc. Also, due to the weakness of the brain signals, we need to implement several filter stages in the hardware to minimize the impact of environmental factors such as city electricity on the main signal, However, due to the tolerance of the components and the drop generated by the filter stages, an active filter should be used. With the benefits of an active filter, the number of stages increases, although the frequency response is more favorable, But due to the increased number of electronic components, more noise is added to the system. To solve this problem, the alternative solution proposed in this project is the removal of hardware filtering steps and transferring it to the software domain. For proper and stable supply, necessary arrangements such as the use of high PSRR regulators are considered. For proper noise margin, EMI issues and etc., the board is designed in 4 layers. The device is connected via a USB port and also Bluetooth. For device verification input noise test and power supply noise test are done. Thanks to the principled design and observance of the guidelines, an excellent noise level of 0.3 μV is obtained. In order to test the device for recording vital signals, an ECG was first recorded and then in the field of EEG, alpha frequency band and eye movement signals recorded.
Keywords: Electroencephalogram, Brain and Computer Interface, EEG, BCI.
