Background: Sampling rate = 10Hz; Electrode placement = Left distal forearm I am using standard AgCl electrodes from bio-medical instruments.
*"Nothing will benefit human health and increase chances for survival of life on Earth as much as the evolution to a vegetarian diet." ~ Albert Einstein (1879 - 1955). Fola Alamudun Computer Engineering Texas A&M University mobile: 469-995-4088 | email: [email protected]* On Wed, Sep 5, 2012 at 5:06 PM, Benjamin Kuris <[email protected]> wrote: > No issues have been reported to Shimmer to the best of my knowledge > (and I would see them). Someone from Shimmer support may contact you > on the firmware side. In the meantime, can you provide background on > your sample rate, electrode type/location, etc.? > Is there a chance that you are sampling too fast (eg. >50Hz)? I'm not > sure if the auto-range function has been tested at fast sample rates. > > Thanks, > Ben > > > On Wed, Sep 5, 2012 at 5:55 PM, Fola Alamudun <[email protected]> > wrote: > > Here is a zoomed figure. > > I suspected just what you said. I have looked over the code I am using > and I > > suspect that the autorange function may need tweaking. > > Your suggestion to shift the range upwards away from the trouble range > and > > maintain a constant range versus autorange may be one good solution. > > However, i'd prefer to find a solution where i can still use autorange. > Data > > collection will be in excess of 6 hours a day and so i am certain a > singular > > range value will not work for our experiments. > > > > The autorange function i am using is the shimmer provided > Gsr.controlRange > > function. Is there a known issue with this? if so is there a workaround > that > > has been tested? > > > > Thanks for your prompt response and i look forward to your reply. > > > > > > "Nothing will benefit human health and increase chances for survival of > life > > on Earth as much as the evolution to a vegetarian diet." ~ Albert > Einstein > > (1879 - 1955). > > > > Fola Alamudun > > Computer Engineering > > Texas A&M University > > mobile: 469-995-4088 | email: [email protected] > > > > > > On Wed, Sep 5, 2012 at 4:43 PM, Benjamin Kuris <[email protected]> wrote: > >> > >> Fola, > >> If you look at the data, the artifact always occurs at the same value > >> (in the y-axis). I suspect that it is an artifact from the > >> auto-ranging function. You are having the issue at ~1.6uS, or 625k. > >> There is a autorange switch at 680k (1470uS), which I think is very > >> suspicious. You could try collecting data without auto-ranging and > >> compare the results -- for example, if you select range2, accuracy > >> will suffer <1470 but you should have the results you want for peaks > >> of GSR activity. > >> > >> Alternatively you could try skin preparation to shift the GSR curve > >> upwards away from the range transition or changing the time constants > >> in the code for auto-ranging. > >> > >> I would also point you to the GSR User Guide Rev 1.0 on the Shimmer > >> website-- what sample rate are you using? Can you provide a > >> sample-level zoom in to one of the saturation periods? > >> > >> -Ben > >> > >> > >> On Wed, Sep 5, 2012 at 5:21 PM, Fola Alamudun <[email protected]> > >> wrote: > >> > I am including images of what the data looks like over a period of > about > >> > 6 > >> > hours of data collection. > >> > Does anyone have any advice on how to fix this issue? I have read that > >> > this > >> > may have to do with pressure on the gsr node which may cause > flat-lining > >> > as > >> > we are seeing in our data. > >> > > >> > > >> > "Nothing will benefit human health and increase chances for survival > of > >> > life > >> > on Earth as much as the evolution to a vegetarian diet." ~ Albert > >> > Einstein > >> > (1879 - 1955). > >> > > >> > Fola Alamudun > >> > Computer Engineering > >> > Texas A&M University > >> > mobile: 469-995-4088 | email: [email protected] > >> > > >> > > >> > On Tue, Sep 4, 2012 at 7:32 PM, Fola Alamudun < > [email protected]> > >> > wrote: > >> >> > >> >> Hello all, > >> >> > >> >> I am having some issues with the shimmer gsr unit. When we configure > >> >> this > >> >> unit to collect data using the auto range function, we notice that > the > >> >> resistance values saturate about half way / three quarter way through > >> >> data > >> >> collection. > >> >> I noticed someone else had experienced this but saw no response to > the > >> >> question and so i am reposting with the hopes to find a solution to > >> >> this > >> >> soonest. > >> >> We are using shimmer gsr and it has an orange padding between the gsr > >> >> unit > >> >> node and the main board (this, i read, was supposed to reduce the > >> >> possibility of the sensor saturating due to pressure). > >> >> Thanks in advance for any help i receive. > >> >> > >> >> > >> >> "Nothing will benefit human health and increase chances for survival > of > >> >> life on Earth as much as the evolution to a vegetarian diet." ~ > Albert > >> >> Einstein (1879 - 1955). > >> >> > >> >> Fola Alamudun > >> >> Computer Engineering > >> >> Texas A&M University > >> >> mobile: 469-995-4088 | email: [email protected] > >> > > >> > > >> > > >> > _______________________________________________ > >> > Shimmer-users mailing list > >> > [email protected] > >> > https://lists.eecs.harvard.edu/mailman/listinfo/shimmer-users > >> > > > > > >
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