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Re: [buildcheapeeg] comADC-EEG

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  • Joerg Hansmann
    hi, ... From: Rob Sacks To: Sent: Thursday, August 09, 2001 1:41 PM Subject: Re: [buildcheapeeg]
    Message 1 of 27 , Aug 9, 2001
      hi,

      ----- Original Message -----
      From: Rob Sacks <editor@...>
      To: <buildcheapeeg@yahoogroups.com>
      Sent: Thursday, August 09, 2001 1:41 PM
      Subject: Re: [buildcheapeeg] comADC-EEG
      ...
      > > The greatest deviation I see, is about 40usec.
      > > That is 1% jitter at 250 Hz sampling clock.
      >
      > Is this big or small? :) I have no idea.


      The simulation shows that even a jitter of 2 ms,
      what is 51.2% jitter at 256 Hz sample clock,
      has not much impact on the FFT of a 8 Hz wave.

      However the waveform is slightly distorted.

      (see pictures)

      Regards,

      Joerg
    • Rob Sacks
      Hi Joerg, Thanks for answering my questions and providing the screen shots. Very interesting, I appreciate it. I ll look at them more carefully over the
      Message 2 of 27 , Aug 10, 2001
        Hi Joerg,

        Thanks for answering my questions and providing
        the screen shots. Very interesting, I appreciate it.
        I'll look at them more carefully over the weekend.

        > I always thought meditation were good for memory ?
        > A friend has told me about earliest childhood memories
        > in a deeply relaxed state.

        I've noticed that old memories often surface
        unexpectedly during meditation but maybe this
        involves a different mental mechanism from the
        attempt to deliberately recall something? Or
        maybe childhood memories are different in this
        respect from memories created in adulthood?

        > That is not necessary. The timer chip could be set to 1193
        > (the exact but impossible value would be 1193.18)
        > and would then produce one interrupt each 1 msec.
        >
        > If you want to check the time in between the interrupts,
        > you simply read out the timer counter register, that
        > is clocked with 1.19318 Mhz.

        Yes, of course you're right. I wasn't thinking.

        > I must admit that I have not the slightest experience with
        > windows programming.

        Oh, how I envy you! :)

        Regards

        Rob
      • peterson@discover-net.net
        ... Rob--This often happens in alpha-theta training as well. I think it s partly because the censors that otherwise guard consciousness are relaxed and let
        Message 3 of 27 , Aug 10, 2001
          --- In buildcheapeeg@y..., "Rob Sacks" <editor@r...> wrote:
          >
          > I've noticed that old memories often surface
          > unexpectedly during meditation but maybe this
          > involves a different mental mechanism from the
          > attempt to deliberately recall something? Or
          > maybe childhood memories are different in this
          > respect from memories created in adulthood?
          >
          Rob--This often happens in alpha-theta training as well. I think
          it's partly because the "censors" that otherwise guard consciousness
          are relaxed and let things in that would otherwise be excluded.
          Also, in this state the mind is less directed by outside stimuli, so
          it is free to wander and follow old associative networks into
          "forgotten" corners, etc. Remember William James' beautiful metaphor
          of the bird flitting from branch to branch? It is definitely very
          different from deliberate retrieval efforts.
        • Rob Sacks
          Hi Jim, One of these days I really must keep my resolution to fire up the old Brainmaster and experiment a bit more with alpha-theta. Thanks for mentioning the
          Message 4 of 27 , Aug 12, 2001
            Hi Jim,

            One of these days I really must keep my resolution
            to fire up the old Brainmaster and experiment a bit
            more with alpha-theta.

            Thanks for mentioning the metaphor. Had to hunt
            it down and realized that although I read Varieties
            of Religious Experience in college, I've never
            even glanced at Principles of Psychology. Plan to
            do so in the next few days. Just began reading the
            chapter in which the metaphor occurs and have
            become entranced. Thanks for mentioning it.

            Regards,

            Rob


            ----- Original Message -----
            From: <peterson@...>
            To: <buildcheapeeg@yahoogroups.com>
            Sent: Friday, August 10, 2001 12:22 PM
            Subject: [buildcheapeeg] Re: comADC-EEG


            > --- In buildcheapeeg@y..., "Rob Sacks" <editor@r...> wrote:
            > >
            > > I've noticed that old memories often surface
            > > unexpectedly during meditation but maybe this
            > > involves a different mental mechanism from the
            > > attempt to deliberately recall something? Or
            > > maybe childhood memories are different in this
            > > respect from memories created in adulthood?
            > >
            > Rob--This often happens in alpha-theta training as well. I think
            > it's partly because the "censors" that otherwise guard consciousness
            > are relaxed and let things in that would otherwise be excluded.
            > Also, in this state the mind is less directed by outside stimuli, so
            > it is free to wander and follow old associative networks into
            > "forgotten" corners, etc. Remember William James' beautiful metaphor
            > of the bird flitting from branch to branch? It is definitely very
            > different from deliberate retrieval efforts.
            >
            >
            >
            > To unsubscribe from this group, send an email to:
            > buildcheapeeg-unsubscribe@egroups.com
            >
            >
            >
            > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
            >
            >
          • jiva@humboldt1.com
            ... I m going to jump in here and make another plug for an on-board A D chip. Plus: Low cost, multi-channel, high-resolution, fast, low cpu consumption, serial
            Message 5 of 27 , Aug 13, 2001
              > > Is possible add 16 bit dig. counter ( or 2 x 8bit ), I think also
              > > cheap.
              > > Time resolutin would be high, I read that new 555 reached output
              > > frekvency at about 2.4 MHz.
              >
              > 2 cheap asychronous counters would be ok.
              > You need a 16 Mhz (or whatever the counters can manage)
              > crystal oscillator to generate the clock for the counter.
              > The 555 would generate a gate time for the 16Mhz clock.
              >

              I'm going to jump in here and make another plug for
              an on-board A>D chip.

              Plus: Low cost, multi-channel, high-resolution, fast,
              low cpu consumption, serial out units only require a few
              opto-isolators for i/o, ...

              Minus: a driver must still provide accurate conversion
              timing and retreive/store the results in a timely manner.
              However this seems much less complicated and requires
              orders of magnitude fewer cpu resources than the
              555/serial port scheme.

              In any case ... the new 555 design is more exciting news
              from Joerg and the group.
            • jiva@humboldt1.com
              ... I m still lurking, learning, and stirring up trouble here. not to worry.
              Message 6 of 27 , Aug 13, 2001
                >
                > I told the person who asked me that I didn't think
                > Windows was good enough for this purpose, but
                > maybe I owe him a correction and an apology.
                >

                I'm still lurking, learning, and stirring up
                trouble here. not to worry.
              • Rob Sacks
                Namaste, Jiva-ji, Yikes, I m sorry! I meant to forward those messages to you but got distracted over the weekend. Glad you saw them. Regards, Rob ... From:
                Message 7 of 27 , Aug 13, 2001
                  Namaste, Jiva-ji,

                  Yikes, I'm sorry! I meant to forward those
                  messages to you but got distracted over the
                  weekend. Glad you saw them.

                  Regards,

                  Rob

                  ----- Original Message -----
                  From: <jiva@...>
                  To: <buildcheapeeg@yahoogroups.com>
                  Sent: Monday, August 13, 2001 11:46 PM
                  Subject: [buildcheapeeg] Re: comADC-EEG


                  >
                  > >
                  > > I told the person who asked me that I didn't think
                  > > Windows was good enough for this purpose, but
                  > > maybe I owe him a correction and an apology.
                  > >
                  >
                  > I'm still lurking, learning, and stirring up
                  > trouble here. not to worry.
                  >
                  >
                  >
                  >
                  >
                  >
                  > To unsubscribe from this group, send an email to:
                  > buildcheapeeg-unsubscribe@egroups.com
                  >
                  >
                  >
                  > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
                  >
                  >
                • Vladimir.K
                  ... I ve finished older variant of comADC-EEG , the gameport. ( I used TLC272 and 9V Battery). Now, I am reading gameport on old Linux box and sending to other
                  Message 8 of 27 , Oct 4, 2001
                    --- In buildcheapeeg@y..., "Joerg Hansmann" <info@j...> wrote:

                    > It is a quick and dirty prototype. The GUI is not finished.
                    > All setup is via #define in the source.
                    > So if you want to run it on your PC you probably
                    > have to make some adjustments and recompile
                    > it with DJGPP (and the allegro gaming library).
                    >
                    > If you are not scared until now, I can mail you the
                    > source code and/or the executable.
                    >
                    > Regards,
                    >
                    > Joerg

                    I've finished older variant of comADC-EEG , the gameport.
                    ( I used TLC272 and 9V Battery).
                    Now, I am reading gameport on old Linux box and sending to
                    other machine (W98) to Electric Guru.

                    Even some experiment with kernel Real Time extension ( KURT ) and
                    altering parameters in joystick driver, results are not perfect. It's
                    only 120MHz Pentium.


                    I would like to try your code for DOS, so if you can, send me, please
                    it. (gogol101@...)

                    One curiosity:
                    I didnt think that 9V is dangerous, but when I mesured resitance of
                    EEG electrod ( home made saline type ) I got el. shock and becaus
                    I had electrode on forehead near eye so I saw light flash.
                    ( I have 9V battery in Ohmmeter).

                    If I remember, you said that RS232EEG is limited to 8( or 6 ) channels
                    for limited bandwith on RS232 ( 115 kbaud).
                    I was suprised when I saw on Linux possible setting for 230 and 460
                    kbaud. I am curious if so high speed is real.

                    Regards
                    Vladimir
                  • Joerg Hansmann
                    Hi Vladimir, ... From: Vladimir.K To: Sent: Thursday, October 04, 2001 6:20 PM Subject: [buildcheapeeg]
                    Message 9 of 27 , Oct 5, 2001
                      Hi Vladimir,

                      ----- Original Message -----
                      From: Vladimir.K <gogol101@...>
                      To: <buildcheapeeg@yahoogroups.com>
                      Sent: Thursday, October 04, 2001 6:20 PM
                      Subject: [buildcheapeeg] Re: comADC-EEG


                      ...
                      > I've finished older variant of comADC-EEG , the gameport.
                      > ( I used TLC272 and 9V Battery).
                      > Now, I am reading gameport on old Linux box and sending to
                      > other machine (W98) to Electric Guru.
                      >
                      > Even some experiment with kernel Real Time extension ( KURT ) and
                      > altering parameters in joystick driver, results are not perfect.

                      What sample rate and how many bits resolution do you get ?

                      > It's
                      > only 120MHz Pentium.
                      >
                      >
                      > I would like to try your code for DOS, so if you can, send me, please
                      > it. (gogol101@...)

                      I will send it via email.
                      However it is for the comADC02 hardware.

                      > One curiosity:
                      > I didnt think that 9V is dangerous, but when I mesured resitance of
                      > EEG electrod ( home made saline type ) I got el. shock and becaus
                      > I had electrode on forehead near eye so I saw light flash.
                      > ( I have 9V battery in Ohmmeter).

                      A normal ohmmeter is not very suitable for measuring electrode
                      impedance, because it uses DC (resulting in electrode
                      polarization) and probably exceeds the limits of IEC601-1
                      (therefore you got the electric shock and the light-effects)


                      > If I remember, you said that RS232EEG is limited to 8( or 6 ) channels

                      6 channels, because the AT90S4433 has only 6 analog multiplexer inputs.

                      > for limited bandwith on RS232 ( 115 kbaud).

                      There are other limiting factors too like ADC conversion speed.

                      > I was suprised when I saw on Linux possible setting for 230 and 460
                      > kbaud. I am curious if so high speed is real.

                      If the UART chip on the mainboard can handle that speed, I see no
                      reason why such settings should not work.
                      For RS232EEG however the upper limit is 115200 baud due to
                      xtal-frequency and minimum possible baudrate divider factor.

                      Regards,

                      Joerg
                    • Vladimir.K
                      Hi Joerg, sory for late answer, I am busy now. ... I have not mesured it yet. My etimation that it s worse than 8 bit on 256 sampling. Now 256 samples per
                      Message 10 of 27 , Oct 11, 2001
                        Hi Joerg,

                        sory for late answer, I am busy now.

                        --- In buildcheapeeg@y..., "Joerg Hansmann" <info@j...> wrote:

                        > What sample rate and how many bits resolution do you get ?
                        >

                        I have not mesured it yet. My etimation that it's worse than 8 bit
                        on 256 sampling. Now 256 samples per second is too high.
                        But there is growing potencial. I saw some tricks with setting
                        interrupt-unmask flag for IDE driver ( prog. hdparm ) and
                        IRQ priority optimalization. ( www.best.com/~cae/irqtune/ )
                        Maybe ideas from irqtune are also worth for DOS programs.

                        I also don't understand all code in joystick driver.

                        > I will send it via email.
                        > However it is for the comADC02 hardware.

                        Than you.

                        Regards
                        Vladimir
                      • Joerg Hansmann
                        Hi Vladimir, ... From: Vladimir.K To: Sent: Thursday, October 11, 2001 3:01 PM Subject: [buildcheapeeg]
                        Message 11 of 27 , Oct 13, 2001
                          Hi Vladimir,

                          ----- Original Message -----
                          From: Vladimir.K <gogol101@...>
                          To: <buildcheapeeg@yahoogroups.com>
                          Sent: Thursday, October 11, 2001 3:01 PM
                          Subject: [buildcheapeeg] Re: comADC-EEG


                          > Hi Joerg,
                          >
                          > sory for late answer, I am busy now.

                          No problem.

                          >
                          > --- In buildcheapeeg@y..., "Joerg Hansmann" <info@j...> wrote:
                          >
                          > > What sample rate and how many bits resolution do you get ?
                          > >
                          >
                          > I have not mesured it yet. My etimation that it's worse than 8 bit
                          > on 256 sampling. Now 256 samples per second is too high.
                          > But there is growing potencial. I saw some tricks with setting
                          > interrupt-unmask flag for IDE driver ( prog. hdparm ) and
                          > IRQ priority optimalization. ( www.best.com/~cae/irqtune/ )
                          > Maybe ideas from irqtune are also worth for DOS programs.

                          While the gameport timing loop is running, simply no interrupt must
                          be processed. Or are you using another technique than polling ?

                          IMO the advantage of simple and low cost hardware of the gameportEEG
                          or comEEG is more than compensated by the resulting difficulties with
                          software.

                          Regards,

                          Joerg
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