Brain Waves calculation

[RogerDias]

Hi, Thank you for your app. It is excellent.

I have a doubt about how the brain waves *(alpha, beta, gamma, etc) are calculated and exported to csv.
1) I know that the absolute values are transmitted at 10Hz. However, which epoch doe the app use to calculate it (FTT window)? It is 256 ~ 1 second?

2) If I change the "Recording Interval", Does the FTT window change? I mean, regardless if I choose "constant" or "1 second" or "1 minute", Is the value that appears in the export file for absolute waves a FFT calculation from 256 points? I am interested to know how changes in the recording interval can change the results for the brain waves.

Thank you in advance.

Roger

[James]

#1 - The absolute values are calculated by the Interaxon SDK, not by my own FFT. Their documentation is here: http://developer.choosemuse.com/researc ... and_Powers

#2 - The recording interval is how often a data snapshot is written to file, it does not change any of the calculations.

[Frs]

Hi, I have a follow up question on #2. If the recording interval is set to say 1 second, is the data that comes within that second lost or is the output for that second the average of the stream data within that second? In other words, what will be the impact on the graph of moving between constant and 1 second intervals? Looking at the constant export, it seems that there are also many stale data exported.
Thanks!

[James]

Interval recording is a snapshot. If you're doing your own FFT processing of RAW EEG data, then you should do constant recording. If you're just looking at the pre-calculated brainwave values, then the 1Hz data will be sufficient for 99% of use cases.

[jon]

Hey James, want to bump this again.

I just got a Muse 2, now that the SDK is discontinued, how can I see how the data is parsed and brainwave bands are calculated? Is it possible to access the firmware?

I've been exploring an Angular app that allows my headset to connect directly to my Mac through Chrome, which has been amazing. Going through that code I can see how the raw data is parsed. But that app doesn't do the brainwave band calculations which is something I'd like to start implementing.

Thanks!

[James]

There's no way that I know of to access the firmware of the device. This wouldn't tell you anything about the data parsing anyway, as this is done in the SDK code.

[jon]

Got it. How can we access the SDK code now? Do you have any of the old documentation that you used to make the API calls in your app?

[James]

It's not mine to share, sorry.