What is the maximum frequency that Ganglion board can pickup from a brain signal?

yumin

I didn't find this info at the docs. Sorry if it is there.

wjcroft

It depends on the sample rate. Default sample rate is 200 hz, but much higher is available with the Wifi shield.

https://www.google.com/search?q=sample+rate+nyquist

William

yumin

Great!

I thought that was something like this, but didn't know what exactly

This is a new concept for me

Thank you very much

bpwork

yumin --

If you stay with 200 samples/second sample-rate, you won't need any of the following.

But if you are able to change to a higher sample rate and you want to go for higher frequencies of some sort, notice this.

Ganglion has a resistor-capacitor 160Hz lowpass filter on each channel.  

For example, for Ganglion's first channel, you can find it as R23 and C10.

You could replace them with other values.

If you know a higher frequency filter setting that you want, you can calculate R and/or C values by:

   f = 1 / (2 * pi * R * C)

Without looking into it more, I'll say it might be good to avoid R's less than about 100 Ohms, and C's less than about 0.01uF.

Adjusting both of those would get the filter to about 16KHz which is presumably more than plenty?  and much above that you would run into the instrumentation amplifier's bandwidth anyway, which would be about 20KHz.

     -- Bruce P.