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Topic: Bioera Coherence VS Neuroguid Coherence
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angel61606



Joined: Jul 8, 2020
Posts: 81

PostPosted: Jan 31, 2022 2:47 AM    Post subject: Bioera Coherence VS Neuroguid Coherence

Hi Jarek

I am using Bh-coherence element to calculate coherence in bioera, and to validate my results I took my data to Neuroguid software. the results show a significant difference, although it seems both Neuroguid and Bioera uses same algorithm,"thacher coherence calculation".
I am wondering why this happens. Another issue I encountered was that apparently the "Bin Count" property of Coherence element plays an important role in the result and it changes it dramatically, why is that?
how can I know what the proper number is ?
jarek



Joined: Oct 22, 2007
Posts: 952

PostPosted: Jan 31, 2022 10:58 AM    Post subject:

I don't know about Neurogui software, so can't tell why it is different. Pretty much every setting can affect results.

The BioEra coherence has been used and tested by many customers. I also used it personally for training and it worked well for me.

"Bin count" determines the size of FFT transform. Larger value may increase precision/resolution of the frequency output. If large enough (256+), it shouldn't change the output "dramatically". It may be different if it is too small.
angel61606



Joined: Jul 8, 2020
Posts: 81

PostPosted: Feb 1, 2022 2:29 AM    Post subject:

I chose Bin Count numbers greater than 1024 , my sampling rate is 250. the thing is Bin count does affect the result so much.
By the way I am wondering if I could somehow get access inside the design of coherence?
you did probably use filters in it, didn't u? The output bits of my filters should be set on 24. If there are any filter there how can i be sure that this property is set correctly?



I have one more request, could you please give me an example design in which you used coherence and got valid results, maybe my implementation is wrong. this way i can figure out where I am being wrong.
jarek



Joined: Oct 22, 2007
Posts: 952

PostPosted: Feb 1, 2022 11:51 AM    Post subject:

The coherence nested design can't be opened. It doesn't have any filters, so perhaps this is what you should add before its 2 inputs in your design. There is nothing special about it, I can't see how a snippet could help, the differences you see probably come from something else.

The option to set bits in Filter element is only applicable for the scalar version. In general the Scalar elements are not recommended for signal processing, they are fine only for integer numbers. The Float version doesn't use this option and it would be my first choice over a Scalar version.
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