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orgicus / Mindwave

Mindwave Mobile EEG headset basic parser
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Meaning of the values eeg[i]. #7

Open manali-s10 opened 3 years ago

manali-s10 commented 3 years ago

Hello sir, I would like to know what exactly the values mean in eeg[i]? I understand that it is not the raw eeg data? is it the eeg power? I want to receive raw eeg amplitude values on arduino serial monitor. please help

orgicus commented 3 years ago

As per ThinkGear Communication Protocol EEG_POWER section:

This Data Value represents the current magnitude of 8 commonly-recognized types of EEG frequency bands (brainwaves). It consists of eight 4-byte floating point numbers in the following order: delta (0.5 - 2.75Hz), theta (3.5 - 6.75Hz), low-alpha (7.5 - 9.25Hz), high-alpha (10 - 11.75Hz), low-beta (13 - 16.75Hz), high-beta (18 - 29.75Hz), low-gamma (31 - 39.75Hz), and mid-gamma (41 - 49.75Hz). These values have no units and therefore are only meaningful when compared to each other and to themselves, for considering relative quantity and temporal fluctuations. The floating point format is standard big-endian IEEE 754, so the 32 bytes of the Values can therefore be directly cast as a float* in C (on big-endian environments) to be used as an array of floats.

Also notice the eeg[i] data can be retrieved as individual values:

  1. eeg[0] = delta()
  2. eeg[1] = theta()
  3. eeg[2] = lowAlpha()
  4. eeg[3] = highAlpha()
  5. eeg[4] = lowBeta()
  6. eeg[5] = highBeta()
  7. eeg[6] = lowGamma()
  8. eeg[7] = midGamma()

(e.g. mindwave.eeg()[0] is the same as mindwave.delta(), etc.)

Hope this thelps, George

manali-s10 commented 3 years ago

Thanks for the information. I want to print the raw eeg values (in volts) on a serial monitor. Can you suggest how to do that?

On Sun, Sep 5, 2021 at 2:56 AM George Profenza @.***> wrote:

As per ThinkGear Communication Protocol http://developer.neurosky.com/docs/doku.php?id=thinkgear_communications_protocol EEG_POWER section:

This Data Value represents the current magnitude of 8 commonly-recognized types of EEG frequency bands (brainwaves). It consists of eight 4-byte floating point numbers in the following order: delta (0.5 - 2.75Hz), theta (3.5 - 6.75Hz), low-alpha (7.5 - 9.25Hz), high-alpha (10 - 11.75Hz), low-beta (13 - 16.75Hz), high-beta (18 - 29.75Hz), low-gamma (31 - 39.75Hz), and mid-gamma (41 - 49.75Hz). These values have no units and therefore are only meaningful when compared to each other and to themselves, for considering relative quantity and temporal fluctuations. The floating point format is standard big-endian IEEE 754, so the 32 bytes of the Values can therefore be directly cast as a float* in C (on big-endian environments) to be used as an array of floats.

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