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62Re: [buildcheapeeg] Re: hi folks

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  • Joerg Hansmann
    Dec 1, 2000
      Hi Rob,

      ----- Original Message -----
      From: Rob Sacks <editor@...>
      To: buildcheapeeg <buildcheapeeg@egroups.com>
      Sent: Thursday, November 30, 2000 7:24 PM
      Subject: Re: [buildcheapeeg] Re: hi folks


      > Joerg,
      >
      > (If I write your name this way, Jörg, does it work?)

      Yes. It looks right. ( A little trick with the ALT-Key ? )

      > > Sounds nice. I am really interested in samples of brainwaves of a meditating
      > > lama. Perhaps Rob could add the feature of recording / viewing
      > > eeg-data files.
      >
      > What should we put in the files?

      e.g.

      1 header:

      4 bytes version_code
      80 char short_description
      1 byte number_of_channels
      1 byte bytes_per_channel
      ?? bytes date_and_time_of_recording_start

      n data-blocks:

      1 byte ch1_hi
      1 byte ch1_lo
      1 byte ch2_hi
      1 byte ch2_lo
      ...
      1 byte chn_hi
      1 byte chn_lo

      ------------end_of_format_description-----------

      As an alternative we could use a data format of commercial
      eeg data logger.

      > If we store all
      > the data (the raw serial input or the microvoltages)
      > the files will be very big.

      If you provide a dialog to store only channels that are used,
      the amount of data will be quite moderate for modern PCs.

      1 second : 256Hz * 2 channels * 2byte/channel = 1024 bytes
      1 minute : 60* 1024 bytes = 61 kB
      1 hour: 60* 61kB = 3.7 MB
      24 h : 24* 3.7 MB= 88 MB

      Lets assume , the lama meditates 1 h , then we would get 3.7 MB
      raw data. Compressed to ZIP -Format it will be below 1 MB

      Regards,

      Joerg
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