[Homer-users] Low pass filter error

[David Boas]

curious.
you get the error for 0.5 Hz on the LPF? If so, then the time vector 
must not be presenting a sample at a 2 Hz sample rate.

I could see the error happening at 1 Hz because of numerical round off 
errors.

David


On 3/11/14, 3:57 PM, Grace Giles wrote:
> Good afternoon,
>
> I am using NIRS data obtained from the Biopac fNIRS system and when I 
> attempt to enter filters in HomER (i.e. 0.00 high pass and 0.5, 1 or 2 
> low pass) I get the error message "Filter parameters exceed Nyquist 
> frequency."
>
> Biopac's sampling frequency is set at 2 Hz, which I believe according 
> to Nyquist's Theorem means that I can only look at signals as fast as 
> 1 Hz, but I am not sure why a filter of 1 is a violation.
>
> Has anyone else using Biopac come across this issue? Any insight would 
> be greatly appreciated. I am using HomER to analyze my data for the 
> first time, so still fairly new.
>
> Best,
> -- 
> Grace Giles
> PhD Candidate
> Nutrition and Behavior Lab
> Department of Psychology
> Tufts University
>
>
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