<h3>Nyquist Principle</h3>
<h3>
</h3>
<h5>The Nyquist principle states that in order to measure a signal you need to measure it at twice the speed of its fastest frequency. Here is&nbsp; a video that covers this principle clearly, and in good detail. Please watch until 13:31.</h5>
<iframe width="560" height="315" src="https://www.youtube.com/embed/FcXZ28BX-xE" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe>
<p><br></p>
<h3>Fast Fourier Transform (FFT)</h3>
<p>The Fast Fourier Transform (FFT) is a way to decompose (and reconstruct) complex waveforms into their disparate frequencies, as well as the amplitudes of those frequencies. This is the matehematical process through which raw EEG is converted into quantitative
    EEG brain maps. Here is a video by Arnaud DeLorme on the FFT process in EEG:</p><p>&nbsp;
    <iframe width="560" height="315" src="https://www.youtube.com/embed/wB417SAbdak?start=180" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen=""></iframe></p>
<p></p><br>
<h3>Gain, Notch Filters, and Bandpass&nbsp;</h3>
<p>This final video is of Neurofield's EEG software, displaying the features of:</p>
<p><b><u>Gain</u></b> - t<span style="font-size: 1rem;">he sensitivity&nbsp;of the recording, measured in microvolts per millimeter. Gain is manipulated to either increase or reduce the display height of waveforms.&nbsp;</span></p>
<p></p>
<p><span><span style=""><b style=""><u>Notch Filters</u>&nbsp;- </b>these filters can be useful in deleting&nbsp;<span style="">fixed-frequency noise sources</span>&nbsp;such as that from electrical line frequency (50 or 60 Hz) noise.&nbsp;</span>
    </span>
</p>
<p><span><span style=""><b style="text-decoration-line: underline;">Bandpass:&nbsp;</b>&nbsp;A band-pass filter or bandpass filter is a device that passes frequencies within a certain range and rejects frequencies outside that range</span></span>
</p>
<p><br></p><p>
</p><iframe src="https://drive.google.com/file/d/1kaqrZSfJmnhQNL_FJ2FSHASiWoduhciT/preview" width="640" height="480" allow="autoplay"></iframe>