Week Five Updates

The voltage amplitude for the average EMG signal is around 0.5mV. This value can differ depending on the specific muscle where the signals are being read. There was no specific voltage amplitude value of the bioelectrical signals found for the orbital orbicularis oculi, the muscle being used, so preliminary testing will be needed to determine the actual voltage range. The actual voltage range can then be used to determine the gain that should be used for the amplifier in order for the voltage to be large enough to be read by MATLAB. To stay within the dynamic range of the DAQ, the signal needs to be amplified to the maximum value of about 1.5V. The equation to find the gain is Gain=(Output Voltage)/(Voltage of EMG Signal before Amplification). Knowing that the output voltage needs to be 1.5V and that the average EMG signal is around 0.5mV, it can be determined that the gain should be set to about 3000.

From the INA2126 data sheet, it was determined that an R_G value, of the gain resistor, should be approximately 26.7 ohms. This was found using the equation 80000 ohms/(Gain-5)=R_G.

More code development was also done. The play, pause, next, and previous commands were put into a simple function. No signal data is available at this point, so arbitrary variable values were used to test. Once the signal data is available, the function will be able to be fully written.

Foobar2000 control function

MATLAB code to interface the instrumentation amplifier with MATLAB were procured, along with code to filter the signal and display the data in a rolling graph. These were mostly premade and little work was done with them. Once the equipment to retrieve the signals is available, more work will able to be done with the code. All codes are available for download through the links below.

Foobar2000 control: http://www.mediafire.com/?htm2t9ycyosjfth
MATLAB and instrumentation amplifier interface: http://www.mediafire.com/?c11gu1uatbgc9n3
Signal processing and display: http://www.mediafire.com/?ttuc16c59qc42au