[Eeglablist] Nyquist, downsampling, and EEG

[Michael D. Nunez]

Hey Eric,

There is still aliasing that can occur past the Nyquist rate. That's why an
Engineer's Nyquist of 2.5 the max desired frequency is often used. Also we
may want to accurately record artifact above 50 Hz to better remove that
artifact.

Furthermore there is no real cost to having large sampling rates, besides
initial file size, in EEG experiments where the analysis is performed
offline. We can always downsample offline. In some online Brain-Computer
Interfaces (BCIs), the sample rate will be a concern.

Michael

On Sun, Mar 3, 2019, 23:32 Eric Rawls <elrawls at email.uark.edu> wrote:

> Hi list, I have a short, more theoretically designed question.
> Typical ERP studies will apply a filter around 50 Hz to remove frequencies
> above line noise.
> Doesn't this mean that for any data filtered this way the highest
> reasonable sampling rate is 50*2=100 Hz?
> So why does we all use 500, or even 1000 Hz, when sampling EEG signals?
> Does this lower limit on the sampling rate need to increase for phase
> based analyses etc?
> I've been curious about this for a while and wanted to open it up to a
> group of experts. Why do we sample above the Nyquist rate in our EEG
> experiments?
> Thanks for the discussion
> Eric Rawls, M.S.
> Graduate Research Assistant & Instructor
> Department of Psychological Sciences
> University of Arkansas
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