Frequency refers to the rate at which a vibration occurs that constitutes a wave—the number of this repeated event (cycles) per unit of time. Calculating the frequency of a repeating waveform is accomplished by counting the number of times the wave occurs within a second, then dividing the count by the length of the time period. EEG measures the frequency in Hz. The intensity of a brainwave is the height or amplitude of the signal and is measured in Microvolts.
EEG records information (known and unknown) in the form of information that is input to the brain, processed, and output as data. Frequency is the speed at which the waveform data is accelerating, and amplitude is the intensity of the waveform, measured by the height of the waveforms. The frequency domains are beta, alpha, theta, and delta. The amplitude values or the height of the brainwave signals are measured from 0 to 20 microvolts and represent the power of the signal.
Recent developments in Open-BCI has resulted in development of the brain-duino device, which extends the frequency range to include measurement of Gamma frequencies— a high frequency range between 40 and 200 Hz. This development facilitates EEG monitoring and analysis, which previously was not possible in an affordable, miniaturized device . For more information see Neurofeedback on the OnAir Network.