Amp timing issues
Agatha Lenartowicz <alenarto@ucla.edu> 12/2/14
to supportteam, Wei, me Hi all. Can you confirm my interpretation of the following statement in the updated advisory. I am to understand that if we used NA300, and NS version 4.5.1 or 4.5.7, then the first column 250 s/s entry should read 8 ms not 36 ms as it currently stands. Furthermore can you confirm that the other entries (specifically 8ms delay for 1000 s/s) for N300 are still correct.
"Furthermore, we found that for data recorded with Net Station versions 4.4 through 4.5.7, the correction values for the default 250 s/s sampling rate (which is likely used by the majority of customers) is 8 ms"
Is that correct? This is relatively important to me - as we are in the process of submission corrections to published manuscript and re-processing our data. Thank you.
Gaynor Foster <gfoster@egi.com> 12/2/14
to Agatha, supportteam, Wei, me Dear Agatha,
The statement in the Advisory is correct, so let me describe this in another way. With the NA 300, for Net Station 4.4 through 4.5.x, the delay values for 125, 500 and 1000 s/s are correct. For 250 s/s, if you click on this sample rate to select it, then the value in the table is also correct. The exception occurs if your 250 s/s sample rate was the result of using the default sample rate associated with the NA 300 Control Panel. In this particular instance, you should use the 8ms delay value.
Do let me know if helps clarify the situation or if you have further questions.
Best Wishes, Gaynor
Agatha Lenartowicz <alenarto@ucla.edu> 12/2/14
to Gaynor, supportteam, Wei, me Gaynor - How do I know - post-hoc - if the 250 s/s was "selected" or left as such "by default". For all practical purposes these are the same. If the default is on then wouldn't the control panel still show the 250 s/s "selected"?
Gaynor Foster <gfoster@egi.com> 12/2/14
to Agatha, supportteam, Wei, me Dear Agatha,
Unfortunately there is no way for us to determine whether the 250 s/s was clicked to select it or used by default. There is the possibility that we can confirm the delay associated with your recordings by reviewing the latency of the sensory ERP components within your processed data. Would you like us to review your data in this way? If so, do you have a study that used visual stimuli?
Best Wishes, Gaynor
Agatha Lenartowicz <alenarto@ucla.edu> 12/2/14
to Gaynor, supportteam, Wei, me Goodness - ok. So this is a real problem that has no immediate solution and we have to accept that in all/some subjects the onsets are just wrong. For instance let's say an RA opened up the control window, changed temporarily to 1000Hz, then changed it back. Would the result be 8 or 36 ms (b/c of the temporary change in the control panel setting) delay? Agatha P.S. I do not require external review of ERPs.
Gaynor Foster <gfoster@egi.com> 12/4/14
to Agatha, supportteam, Wei, me Dear Agatha,
In the scenario that you describe, a temporary change to the control panel setting, the result would be the 250 s/s expected delay value of 36 ms. It is only when there is no change to the default use of the 250 s/s sample rate that we see the 8 ms delay.
I extend my sincere apologies to you for the additional work and frustration this error has caused you. Your second sentence does accurately describe the situation for you, and while I cannot change that I am here to help as much as I can. Please let me know if there is anything I can do.
Best Wishes, Gaynor
Agatha Lenartowicz <alenarto@g.ucla.edu> 12/4/14
to Gaynor, Agatha, supportteam, Wei, me Thank you Gaynor for your continued support. This is definitely not great but we'll survive. It should be fixable. To a smooth 2015 :)
Gaynor Foster <gfoster@egi.com> 12/5/14
to Agatha, Agatha, supportteam, Wei, me Hear, hear … to a smooth 2015 :-)
Thank you for your understanding, Agatha, it is much appreciated.