Raw_FFT frequencies and the microvolts connected question


#1

Dear All,

I have now looked in all Muse documentation and all items in the forum, but is still not clear how to get the FFT frequency with the microvolts connected to this frequencies.
For a EEG reading we need the Frequency and the amplitude in microvolts for it and for every channel.
The Raw_FFT0, Raw_FFT1, Raw_FFT2 and Raw_FFT0, a big array with all frequencies at a given time, but where are the corresponding amplitudes in microvolts for this array in a given time?
I cannot work out how to link this frequencies to the amplitudes in microvolts, any help from the developers?
excample: 6.1760025024414 Hz; 1307.75939941406 microvolts etc. etc. etc.

The FFT data is not in microvolts. It is measured in log(uV^2/Hz). Only the time domain EEG data is in microvolts.
So how to calculate from the microvolts the frequency? or link this to the FFT data?

I hope any one can help me out here.

Many thanks

my output example to find out how it works. I use this output so I have my clear separators to work on.


#2

Hi HvM,

The /muse/elements/raw_fft0 data contains the log PSD (Power Spectral Density) coefficients for each frequency bin. PSD is a measure of power. There isn’t really any such thing as “power” in microvolts. But the power of a signal that is expressed in microvolts can be estimated, and to that end we use PSD.

So, the numbers in the /muse/elements/raw_fft0 array are power values. They are related to the /muse/eeg uV data by the fact that they are derived from the Fast Fourier Transform of that data.

The only data that is measured in uV is the /muse/eeg data. So, you don’t need to invert the FFT values back to the time domain to get the original signal in uV, because the original signal is already provided to you.

Can you clarify what you’re looking for? What are you trying to achieve with the data? If you want to measure “how much” of a certain frequency or group of frequencies is represented in the data, then you can already do that with the /muse/elements/raw_fftX data streams, or streams like /muse/elements/alpha_relative, /muse/elements/beta_relative, etc.


#3

Dear Tom,

I like to get the Frequencie and the power to it, with this I workout the emotions from it.
As a example Hz and power per channel: 12,780237 (Hz), 880.064453125 (relative uV) etc…

/muse/elements/low_freqs_absolute (are this real frequencies?)
/muse/elements/alpha_absolute (are this frequencies? or Power value?)
/muse/elements/alpha_session_score (are this frequencies? or Power value?)
/muse/elements/alpha_relative (are this frequencies? or Power value?)

are this elements related? and how?

I have used many EEG scanners but it had just per channer the Frequency in Hz and the relative power in uV, from this we worked out the specific pattern algorithm in waves per brain sector how the are connected to emotions. So I like to know if it is possible to get the Frequency in Hz with the power of this frequency per sensor.


#4

OK, I think I understand. I answered a similar question in this thread: http://forum.choosemuse.com/forum/developer-forum/3139-the-number-of-fft-data

Quoting from that answer:

"To get the frequency resolution for the bins, you can divide the sampling rate by the FFT length, so in the case of Muse: 220/256 ~ 0.86Hz/bin

So, the zeroth index of the FFT array represents 0Hz, the next index represents 0-0.86Hz, and so on up to 128*0.86 = 110Hz, which is the maximum frequency that our FFT with its 220Hz sampling rate can detect."

Also, like I said, there is no such thing as power in uV. So there isn’t really a way to have (frequency, power in uV) value pairs, because the second number doesn’t make sense. The /muse/elements/raw_fftX arrays contain the power values for each frequency, but they are in units of 10*log(PSD), not uV. So, you can definitely have (frequency, power) value pairs, it’s just that the power values are fundamentally not in uV.

For instance, you could create a set of (frequency, power) value pairs like so: (i*0.86, /muse/elements/raw_fft0[i]) where i is the index of some element in the /muse/elements/raw_fft0 array. That gives you each frequency with its corresponding power.

[B]/muse/elements/low_freqs_absolute [/B]- This is the [B]absolute power [/B]of frequencies from 1-8Hz. So, we calculate the power for the whole spectrum and take only the sum of the values from 1-8Hz and output them here.
[B]/muse/elements/alpha_absolute[/B] - This is the [B]absolute power [/B]of the Alpha band, which we define as 9-13Hz. Same idea as the low_freqs_absolute, but for a different band of frequencies.
[B]/muse/elements/alpha_session_score [/B]- This is [B]not[/B] a measure of power. It is the output of a special scoring function that we describe on the developer website:

[I]“Session scores gives values between 0 and 1 by comparing the user’s current band power value to an average of their recent historical values of that same band. For example, if the user’s historical alpha power has been between 0.2 and 0.4, and their current alpha power is 0.3, then their session score will be 0.5 since 0.3 is halfway between 0.2 and 0.4.”[/I]

[B]/muse/elements/alpha_relative[/B] - This is the [B]relative power [/B]of the Alpha band. So, the absolute power of the alpha band as calculated before, but then divided by the sum of the power in the rest of the spectrum. Basically, what percentage of the signal’s power is in the Alpha band, rather than an absolute number.

The developer site documents what these paths contain, please take a look there: https://sites.google.com/a/interaxon.ca/muse-developer-site/museio/osc-paths/osc-paths---v3-6-0


#5

Dear Tom,

This is a great help you give me.
Now I understand the way Muse is working and I can work on now.
This is my calculation for every element in the array from /muse/elements/raw_fft0 to see if I have it all correct.
[TABLE=“border: 0, cellpadding: 0, cellspacing: 0”]
[TR]
[TD]/muse/elements/raw_fft0 single (220/256) = 0,86 Hz steps per item index[/TD]
[TD=“align: right”]0.859375[/TD]
[TD]Hz step[/TD]
[/TR]
[TR]
[TD]10*log(PSD) power value for every frequency step[/TD]
[TD] [/TD]
[TD]Hz[/TD]
[/TR]
[TR]
[TD=“align: right”]1.508993149[/TD]
[TD] [/TD]
[TD=“align: right”]0[/TD]
[/TR]
[TR]
[TD=“align: right”]26.15193367[/TD]
[TD] [/TD]
[TD=“align: right”]0.859375[/TD]
[/TR]
[TR]
[TD=“align: right”]20.69542313[/TD]
[TD] [/TD]
[TD=“align: right”]1.71875[/TD]
[/TR]
[TR]
[TD=“align: right”]14.37875748[/TD]
[TD] [/TD]
[TD=“align: right”]2.578125[/TD]
[/TR]
[TR]
[TD=“align: right”]9.221055031[/TD]
[TD] [/TD]
[TD=“align: right”]3.4375[/TD]
[/TR]
[TR]
[TD=“align: right”]8.054722786[/TD]
[TD] [/TD]
[TD=“align: right”]4.296875[/TD]
[/TR]
[TR]
[TD=“align: right”]6.449023247[/TD]
[TD] [/TD]
[TD=“align: right”]5.15625[/TD]
[/TR]
[TR]
[TD=“align: right”]4.11302948[/TD]
[TD] [/TD]
[TD=“align: right”]6.015625[/TD]
[/TR]
[TR]
[TD=“align: right”]0.304226011[/TD]
[TD] [/TD]
[TD=“align: right”]6.875[/TD]
[/TR]
[TR]
[TD=“align: right”]4.417870522[/TD]
[TD] [/TD]
[TD=“align: right”]7.734375[/TD]
[/TR]
[TR]
[TD=“align: right”]0.994097948[/TD]
[TD] [/TD]
[TD=“align: right”]8.59375[/TD]
[/TR]
[TR]
[TD=“align: right”]-0.31560567[/TD]
[TD] [/TD]
[TD=“align: right”]9.453125[/TD]
[/TR]
[TR]
[TD=“align: right”]-3.682043791[/TD]
[TD] [/TD]
[TD=“align: right”]10.3125[/TD]
[/TR]
[TR]
[TD=“align: right”]-4.97032547[/TD]
[TD] [/TD]
[TD=“align: right”]11.171875[/TD]
[/TR]
[TR]
[TD=“align: right”]-9.131807327[/TD]
[TD] [/TD]
[TD=“align: right”]12.03125[/TD]
[/TR]
[TR]
[TD=“align: right”]-6.431248665[/TD]
[TD] [/TD]
[TD=“align: right”]12.890625[/TD]
[/TR]
[TR]
[TD=“align: right”]-5.678417683[/TD]
[TD] [/TD]
[TD=“align: right”]13.75[/TD]
[/TR]
[TR]
[TD=“align: right”]-7.742702007[/TD]
[TD] [/TD]
[TD=“align: right”]14.609375[/TD]
[/TR]
[TR]
[TD=“align: right”]-5.362759113[/TD]
[TD] [/TD]
[TD=“align: right”]15.46875[/TD]
[/TR]
[TR]
[TD=“align: right”]-4.303207397[/TD]
[TD] [/TD]
[TD=“align: right”]16.328125[/TD]
[/TR]
[TR]
[TD=“align: right”]-6.533067703[/TD]
[TD] [/TD]
[TD=“align: right”]17.1875[/TD]
[/TR]
[TR]
[TD=“align: right”]-10.67501068[/TD]
[TD] [/TD]
[TD=“align: right”]18.046875[/TD]
[/TR]
[TR]
[TD=“align: right”]-6.905595303[/TD]
[TD] [/TD]
[TD=“align: right”]18.90625[/TD]
[/TR]
[TR]
[TD=“align: right”]-14.63321209[/TD]
[TD] [/TD]
[TD=“align: right”]19.765625[/TD]
[/TR]
[TR]
[TD=“align: right”]-9.58368206[/TD]
[TD] [/TD]
[TD=“align: right”]20.625[/TD]
[/TR]
[TR]
[TD=“align: right”]-6.694487095[/TD]
[TD] [/TD]
[TD=“align: right”]21.484375[/TD]
[/TR]
[TR]
[TD=“align: right”]-7.67754221[/TD]
[TD] [/TD]
[TD=“align: right”]22.34375[/TD]
[/TR]
[TR]
[TD=“align: right”]-14.89307308[/TD]
[TD] [/TD]
[TD=“align: right”]23.203125[/TD]
[/TR]
[TR]
[TD=“align: right”]-11.45556068[/TD]
[TD] [/TD]
[TD=“align: right”]24.0625[/TD]
[/TR]
[TR]
[TD=“align: right”]-10.30284882[/TD]
[TD] [/TD]
[TD=“align: right”]24.921875[/TD]
[/TR]
[TR]
[TD=“align: right”]-14.27096176[/TD]
[TD] [/TD]
[TD=“align: right”]25.78125[/TD]
[/TR]
[TR]
[TD=“align: right”]-13.01818085[/TD]
[TD] [/TD]
[TD=“align: right”]26.640625[/TD]
[/TR]
[TR]
[TD=“align: right”]-11.67738056[/TD]
[TD] [/TD]
[TD=“align: right”]27.5[/TD]
[/TR]
[TR]
[TD=“align: right”]-12.79998493[/TD]
[TD] [/TD]
[TD=“align: right”]28.359375[/TD]
[/TR]
[TR]
[TD=“align: right”]-11.58601665[/TD]
[TD] [/TD]
[TD=“align: right”]29.21875[/TD]
[/TR]
[TR]
[TD=“align: right”]-14.32905579[/TD]
[TD] [/TD]
[TD=“align: right”]30.078125[/TD]
[/TR]
[TR]
[TD=“align: right”]-9.400168419[/TD]
[TD] [/TD]
[TD=“align: right”]30.9375[/TD]
[/TR]
[TR]
[TD=“align: right”]-9.950563431[/TD]
[TD] [/TD]
[TD=“align: right”]31.796875[/TD]
[/TR]
[TR]
[TD=“align: right”]-13.1291151[/TD]
[TD] [/TD]
[TD=“align: right”]32.65625[/TD]
[/TR]
[TR]
[TD=“align: right”]-15.41500282[/TD]
[TD] [/TD]
[TD=“align: right”]33.515625[/TD]
[/TR]
[TR]
[TD=“align: right”]-14.88709927[/TD]
[TD] [/TD]
[TD=“align: right”]34.375[/TD]
[/TR]
[TR]
[TD=“align: right”]-12.82540417[/TD]
[TD] [/TD]
[TD=“align: right”]35.234375[/TD]
[/TR]
[TR]
[TD=“align: right”]-11.6143465[/TD]
[TD] [/TD]
[TD=“align: right”]36.09375[/TD]
[/TR]
[TR]
[TD=“align: right”]-10.6613245[/TD]
[TD] [/TD]
[TD=“align: right”]36.953125[/TD]
[/TR]
[TR]
[TD=“align: right”]-11.40077686[/TD]
[TD] [/TD]
[TD=“align: right”]37.8125[/TD]
[/TR]
[TR]
[TD=“align: right”]-16.14495087[/TD]
[TD] [/TD]
[TD=“align: right”]38.671875[/TD]
[/TR]
[TR]
[TD=“align: right”]-15.80030823[/TD]
[TD] [/TD]
[TD=“align: right”]39.53125[/TD]
[/TR]
[TR]
[TD=“align: right”]-15.73079967[/TD]
[TD] [/TD]
[TD=“align: right”]40.390625[/TD]
[/TR]
[TR]
[TD=“align: right”]-23.76450729[/TD]
[TD] [/TD]
[TD=“align: right”]41.25[/TD]
[/TR]
[TR]
[TD=“align: right”]-19.35881424[/TD]
[TD] [/TD]
[TD=“align: right”]42.109375[/TD]
[/TR]
[TR]
[TD=“align: right”]-19.0314045[/TD]
[TD] [/TD]
[TD=“align: right”]42.96875[/TD]
[/TR]
[TR]
[TD=“align: right”]-13.66486549[/TD]
[TD] [/TD]
[TD=“align: right”]43.828125[/TD]
[/TR]
[TR]
[TD=“align: right”]-13.07941628[/TD]
[TD] [/TD]
[TD=“align: right”]44.6875[/TD]
[/TR]
[TR]
[TD=“align: right”]-12.85451031[/TD]
[TD] [/TD]
[TD=“align: right”]45.546875[/TD]
[/TR]
[TR]
[TD=“align: right”]-13.60674286[/TD]
[TD] [/TD]
[TD=“align: right”]46.40625[/TD]
[/TR]
[TR]
[TD=“align: right”]-16.57387543[/TD]
[TD] [/TD]
[TD=“align: right”]47.265625[/TD]
[/TR]
[TR]
[TD=“align: right”]-16.54442787[/TD]
[TD] [/TD]
[TD=“align: right”]48.125[/TD]
[/TR]
[TR]
[TD=“align: right”]-4.912025452[/TD]
[TD] [/TD]
[TD=“align: right”]48.984375[/TD]
[/TR]
[TR]
[TD=“align: right”]0.040171113[/TD]
[TD] [/TD]
[TD=“align: right”]49.84375[/TD]
[/TR]
[TR]
[TD=“align: right”]-6.893879414[/TD]
[TD] [/TD]
[TD=“align: right”]50.703125[/TD]
[/TR]
[TR]
[TD=“align: right”]-16.35949516[/TD]
[TD] [/TD]
[TD=“align: right”]51.5625[/TD]
[/TR]
[TR]
[TD=“align: right”]-18.67317581[/TD]
[TD] [/TD]
[TD=“align: right”]52.421875[/TD]
[/TR]
[TR]
[TD=“align: right”]-23.3032608[/TD]
[TD] [/TD]
[TD=“align: right”]53.28125[/TD]
[/TR]
[TR]
[TD=“align: right”]-23.24198341[/TD]
[TD] [/TD]
[TD=“align: right”]54.140625[/TD]
[/TR]
[TR]
[TD=“align: right”]-20.71108437[/TD]
[TD] [/TD]
[TD=“align: right”]55[/TD]
[/TR]
[TR]
[TD=“align: right”]-18.85361481[/TD]
[TD] [/TD]
[TD=“align: right”]55.859375[/TD]
[/TR]
[TR]
[TD=“align: right”]-26.52475548[/TD]
[TD] [/TD]
[TD=“align: right”]56.71875[/TD]
[/TR]
[TR]
[TD=“align: right”]-25.12257195[/TD]
[TD] [/TD]
[TD=“align: right”]57.578125[/TD]
[/TR]
[TR]
[TD=“align: right”]-26.86001778[/TD]
[TD] [/TD]
[TD=“align: right”]58.4375[/TD]
[/TR]
[TR]
[TD=“align: right”]-33.43465424[/TD]
[TD] [/TD]
[TD=“align: right”]59.296875[/TD]
[/TR]
[TR]
[TD=“align: right”]-29.85926247[/TD]
[TD] [/TD]
[TD=“align: right”]60.15625[/TD]
[/TR]
[TR]
[TD=“align: right”]-26.41041374[/TD]
[TD] [/TD]
[TD=“align: right”]61.015625[/TD]
[/TR]
[TR]
[TD=“align: right”]-22.71764565[/TD]
[TD] [/TD]
[TD=“align: right”]61.875[/TD]
[/TR]
[TR]
[TD=“align: right”]-19.97197723[/TD]
[TD] [/TD]
[TD=“align: right”]62.734375[/TD]
[/TR]
[TR]
[TD=“align: right”]-20.68037796[/TD]
[TD] [/TD]
[TD=“align: right”]63.59375[/TD]
[/TR]
[TR]
[TD=“align: right”]-25.37778091[/TD]
[TD] [/TD]
[TD=“align: right”]64.453125[/TD]
[/TR]
[TR]
[TD=“align: right”]-18.31983376[/TD]
[TD] [/TD]
[TD=“align: right”]65.3125[/TD]
[/TR]
[TR]
[TD=“align: right”]-15.4074192[/TD]
[TD] [/TD]
[TD=“align: right”]66.171875[/TD]
[/TR]
[TR]
[TD=“align: right”]-18.25201416[/TD]
[TD] [/TD]
[TD=“align: right”]67.03125[/TD]
[/TR]
[TR]
[TD=“align: right”]-21.84318352[/TD]
[TD] [/TD]
[TD=“align: right”]67.890625[/TD]
[/TR]
[TR]
[TD=“align: right”]-17.0556469[/TD]
[TD] [/TD]
[TD=“align: right”]68.75[/TD]
[/TR]
[TR]
[TD=“align: right”]-15.16582298[/TD]
[TD] [/TD]
[TD=“align: right”]69.609375[/TD]
[/TR]
[TR]
[TD=“align: right”]-19.77409744[/TD]
[TD] [/TD]
[TD=“align: right”]70.46875[/TD]
[/TR]
[TR]
[TD=“align: right”]-17.88751411[/TD]
[TD] [/TD]
[TD=“align: right”]71.328125[/TD]
[/TR]
[TR]
[TD=“align: right”]-17.98021126[/TD]
[TD] [/TD]
[TD=“align: right”]72.1875[/TD]
[/TR]
[TR]
[TD=“align: right”]-14.18812561[/TD]
[TD] [/TD]
[TD=“align: right”]73.046875[/TD]
[/TR]
[TR]
[TD=“align: right”]-18.42290306[/TD]
[TD] [/TD]
[TD=“align: right”]73.90625[/TD]
[/TR]
[TR]
[TD=“align: right”]-16.65641594[/TD]
[TD] [/TD]
[TD=“align: right”]74.765625[/TD]
[/TR]
[TR]
[TD=“align: right”]-19.60476303[/TD]
[TD] [/TD]
[TD=“align: right”]75.625[/TD]
[/TR]
[TR]
[TD=“align: right”]-15.85516453[/TD]
[TD] [/TD]
[TD=“align: right”]76.484375[/TD]
[/TR]
[TR]
[TD=“align: right”]-15.02859497[/TD]
[TD] [/TD]
[TD=“align: right”]77.34375[/TD]
[/TR]
[TR]
[TD=“align: right”]-19.43605804[/TD]
[TD] [/TD]
[TD=“align: right”]78.203125[/TD]
[/TR]
[TR]
[TD=“align: right”]-18.83172035[/TD]
[TD] [/TD]
[TD=“align: right”]79.0625[/TD]
[/TR]
[TR]
[TD=“align: right”]-19.21836853[/TD]
[TD] [/TD]
[TD=“align: right”]79.921875[/TD]
[/TR]
[TR]
[TD=“align: right”]-15.64652538[/TD]
[TD] [/TD]
[TD=“align: right”]80.78125[/TD]
[/TR]
[TR]
[TD=“align: right”]-15.36004543[/TD]
[TD] [/TD]
[TD=“align: right”]81.640625[/TD]
[/TR]
[TR]
[TD=“align: right”]-15.20873928[/TD]
[TD] [/TD]
[TD=“align: right”]82.5[/TD]
[/TR]
[TR]
[TD=“align: right”]-19.99263573[/TD]
[TD] [/TD]
[TD=“align: right”]83.359375[/TD]
[/TR]
[TR]
[TD=“align: right”]-16.42461205[/TD]
[TD] [/TD]
[TD=“align: right”]84.21875[/TD]
[/TR]
[TR]
[TD=“align: right”]-16.75746346[/TD]
[TD] [/TD]
[TD=“align: right”]85.078125[/TD]
[/TR]
[TR]
[TD=“align: right”]-17.8646698[/TD]
[TD] [/TD]
[TD=“align: right”]85.9375[/TD]
[/TR]
[TR]
[TD=“align: right”]-14.48857594[/TD]
[TD] [/TD]
[TD=“align: right”]86.796875[/TD]
[/TR]
[TR]
[TD=“align: right”]-19.17559624[/TD]
[TD] [/TD]
[TD=“align: right”]87.65625[/TD]
[/TR]
[TR]
[TD=“align: right”]-19.49066734[/TD]
[TD] [/TD]
[TD=“align: right”]88.515625[/TD]
[/TR]
[TR]
[TD=“align: right”]-18.16371918[/TD]
[TD] [/TD]
[TD=“align: right”]89.375[/TD]
[/TR]
[TR]
[TD=“align: right”]-22.24616051[/TD]
[TD] [/TD]
[TD=“align: right”]90.234375[/TD]
[/TR]
[TR]
[TD=“align: right”]-22.45903969[/TD]
[TD] [/TD]
[TD=“align: right”]91.09375[/TD]
[/TR]
[TR]
[TD=“align: right”]-20.10883904[/TD]
[TD] [/TD]
[TD=“align: right”]91.953125[/TD]
[/TR]
[TR]
[TD=“align: right”]-15.70566559[/TD]
[TD] [/TD]
[TD=“align: right”]92.8125[/TD]
[/TR]
[TR]
[TD=“align: right”]-16.67168045[/TD]
[TD] [/TD]
[TD=“align: right”]93.671875[/TD]
[/TR]
[TR]
[TD=“align: right”]-20.34294128[/TD]
[TD] [/TD]
[TD=“align: right”]94.53125[/TD]
[/TR]
[TR]
[TD=“align: right”]-19.97132492[/TD]
[TD] [/TD]
[TD=“align: right”]95.390625[/TD]
[/TR]
[TR]
[TD=“align: right”]-18.66082191[/TD]
[TD] [/TD]
[TD=“align: right”]96.25[/TD]
[/TR]
[TR]
[TD=“align: right”]-22.39008331[/TD]
[TD] [/TD]
[TD=“align: right”]97.109375[/TD]
[/TR]
[TR]
[TD=“align: right”]-20.00423431[/TD]
[TD] [/TD]
[TD=“align: right”]97.96875[/TD]
[/TR]
[TR]
[TD=“align: right”]-7.706249714[/TD]
[TD] [/TD]
[TD=“align: right”]98.828125[/TD]
[/TR]
[TR]
[TD=“align: right”]-4.036851883[/TD]
[TD] [/TD]
[TD=“align: right”]99.6875[/TD]
[/TR]
[TR]
[TD=“align: right”]-16.17043304[/TD]
[TD] [/TD]
[TD=“align: right”]100.546875[/TD]
[/TR]
[TR]
[TD=“align: right”]-21.55810928[/TD]
[TD] [/TD]
[TD=“align: right”]101.40625[/TD]
[/TR]
[TR]
[TD=“align: right”]-20.35316277[/TD]
[TD] [/TD]
[TD=“align: right”]102.265625[/TD]
[/TR]
[TR]
[TD=“align: right”]-18.3348465[/TD]
[TD] [/TD]
[TD=“align: right”]103.125[/TD]
[/TR]
[TR]
[TD=“align: right”]-21.3344593[/TD]
[TD] [/TD]
[TD=“align: right”]103.984375[/TD]
[/TR]
[TR]
[TD=“align: right”]-25.62555313[/TD]
[TD] [/TD]
[TD=“align: right”]104.84375[/TD]
[/TR]
[TR]
[TD=“align: right”]-24.39875603[/TD]
[TD] [/TD]
[TD=“align: right”]105.703125[/TD]
[/TR]
[TR]
[TD=“align: right”]-21.73274803[/TD]
[TD] [/TD]
[TD=“align: right”]106.5625[/TD]
[/TR]
[TR]
[TD=“align: right”]-20.75772476[/TD]
[TD] [/TD]
[TD=“align: right”]107.421875[/TD]
[/TR]
[TR]
[TD=“align: right”]-21.29290771[/TD]
[TD] [/TD]
[TD=“align: right”]108.28125[/TD]
[/TR]
[TR]
[TD=“align: right”]-25.32092285[/TD]
[TD] [/TD]
[TD=“align: right”]109.140625[/TD]
[/TR]
[/TABLE]


#6

Dear HvM,

your results seems to be logical. I also have muse device but I have not manages to save PSD yet. As I have experience with EEg ans an engineer I am maybe able to see if results are OK if I can see the actual spectrum somewhere. So, can you put it somewhere, or send me, just one graph with PSD so I can, se,e based on the dat aitself.

regards
Marko

m_car

at

yahooo


#7

Dear Tom,
Your answer is much appreciated, thank you.
I had tried sum up the value of elements/raw_fftx ( 9-13 Hz), but the sum is much different from the value of alpha_absolute, I don’t know why…
Would you know any reason why this might happen?

Thanks