Frequency Range of Cyton 8 channel 32 bit board

faheemershfaheemersh
in Cyton
I've tried searching through the forums - what is the frequency range for EEG with the Cyton 32 bit board?

Comments

  • wjcroftwjcroft Mount Shasta, CA
    http://openbci.com/forum/index.php?p=/search&Search=nyquist

    It depends on the sample rate. A number of ways to increase this beyond 250 hz: Wifi Shield, record to SDcard, etc.

  • faheemershfaheemersh
    Okay, right, thank you. I wasn't thinking when I posted. So our frequency range would be 0-500 Hz approximately, since we can't go higher than 250 Hz sampling rate.
  • wjcroftwjcroft Mount Shasta, CA
    No. Read the search link posts I gave above.

    With two samples per waveform, 250 hz sample rate would record (very poorly) a 125 hz sine wave. Only two samples per wave. More conservative and safe would use 5 or more samples per wave: 250/5 = 50 hz.
  • faheemershfaheemersh
    I'm sorry, I completely misread the inequality when I said that. I looked a the second link, recalled that I knew the relationship, and then impulsively responded without checking the first link. I remember the relationship between nyquist frequency and the highest frequency component of a signal, but just mixed up the variables. 

    Now that I've made myself look silly, I'll use this moment to remind myself (and everyone else that is as goofy as I am) that the relationship between nyquist frequency (fs) and the highest possible frequency (fh) from the signal (if you don't want an aliasing issue) is fs ≥ fh*2, and not the other way around. That's why a fs=250 Hz would poorly record a fh=125 Hz sine wave and why it makes sense to be more conservative by dividing the sampling frequency.

    I asked because I'm thinking about what frequency band we should be extracting from our common spatial patterns features. One of our project advisor's students suggested filtering on a single 0-100 Hz band instead of what we were doing, which was separately filtering from 8-12 Hz and 12-30 Hz after CSP, since we're interested in a motor execution/imagery application. 

    Thank you for correcting me, I really appreciate it! 
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