Muse 2016 Sampling Rate

[Mindman]

I've been doing some data analysis on the mind monitor data from a 2016 Muse. The lengths of my sessions are 25 minutes and the 2016 Muse sampling rate is supposed to be 256 Hz. However, mind monitor only gives me around 1500 samples per session. Anyone know why this might be? The number of samples are not the same so I know there's not some hard cap that they're running into.

[James]

The default is set to record at 1Hz, you can change this in settings to "Constant" which will give you 220Hz data on a 2014 Muse and 256Hz on all other versions of the Muse.
However you only need the full 256Hz RAW EEG data if you are going to do your own FFTs.

[sidratulmoontaha]

Hi james,
Since I have multiple sessions from multiple participant and I am receiving 256±3Hz, do you suggest to resample it to 256 Hz before any processing? Thanks in advanced.

[James]

The last time I asked Interaxon about this, they said to ignore the discrepancies and treat the data as if it was 256Hz exactly. They say that in the hardware the data is generated at exactly 256Hz, but that bluetooth packet delay is what bunches it up.

[igz25]

The last time I asked Interaxon about this, they said to ignore the discrepancies and treat the data as if it was 256Hz exactly. They say that in the hardware the data is generated at exactly 256Hz, but that bluetooth packet delay is what bunches it up.

so are you saying for data sampled at the default rate, we can still perform spectral analysis for 256Hz?

Although when I plot the PSD, I can't see the line noise (60Hz)

[James]

The default recording rate for CSV files is 1Hz, so no; you can only do an FFT if you recorded data at the full data rate. If you're asking about ignoring noisy timestamp delta, then yes use a 256 window on your FFT.

You'll only see line noise if you're near a noise source like a floor lamp. If you switch to the discrete frequency graph and stand next to a lamp, there will be a very obvious spike.