log system-time as timestamp while recording EEG ?

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maschu
Posts: 4
Joined: 25 Apr 2014, 10:23

log system-time as timestamp while recording EEG ?

Post by maschu » 13 Jun 2014, 11:04

Hello I have a further more detailed question:

I wonder, if there is a possibility, to log and present the system-time(as a kind of timestamp)while recording the EEG-Data with BCI2000?
The Idea is to get recorded data relative to the system-time and parallel a log of events as well relative to the system-time.
And simply to compare them to each other.

Is there such a function. Or could someone tell me, how it could be implemented?

Best regards

Mascha
Last edited by maschu on 14 Jun 2014, 07:14, edited 1 time in total.

boulay
Posts: 382
Joined: 25 Dec 2011, 21:14

Re: log system-time as timestamp while recording EEG ?

Post by boulay » 13 Jun 2014, 22:38

I'm sorry I can't find find the location in the documentation (doc.bci2000.org) for creating a log file. Anyway, if you can find that, then you can try doing that and then working backwards from the times in the log file to determine the sample times in system time.

However, if you need more precision than that (e.g., you don't trust the timing of your EEG hardware or whatever is generating your other events) then you should provide intermittent synchronization signals to both devices. There are many ways to do this, but one way would be to have your peripheral device (generating other events) send TTLs to the digital input of your EEG hardware. It's hard to be more specific without know exactly what you want to do and what hardware you're using.

maschu
Posts: 4
Joined: 25 Apr 2014, 10:23

Re: log system-time as timestamp while recording EEG ?

Post by maschu » 14 Jun 2014, 07:27

Hello Boulay,
thanks for Your fast response.

The question about the unpreciousness of my program generating the events will be the next one. :-D
At the current time I would simply like to save the occurence of events at some point of the EEG-Data.

At first it actually should be enougth to track the start and the endpoint of the event-Session inside the EEG-Data.
Maybe as the input of one unused channel?
But at that point I am again confused, how to do that??

Finally My goal is very simple: I want to connect an external stimulation tool to the BCI2000 Recorder/Analyzer, so that I then can examine, how the EEG-Data is related to the stimuli.

best regards

Mascha

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