Event marker / external trigger - WITHOUT hardware?
Hello. I got some problems in placing event markers with real time EEG. My experiment requires touchpad, and event markers are needed for data analysis. External trigger using hardware is not suitable for my experiment. May you recommend some software/methods to solve this problem? Thanks so much !
Comments
Buzz, hi.
You may be able to use an area on your (tablet?) output screen as an optical trigger source. This DOES use a hardware photo detector, but that detector is only connected to the Cyton, not to any external computer. See,
http://openbci.com/forum/index.php?p=/discussion/1928/timestamps-to-sync-stimulus-and-eeg-vs-external-hardware-trigger
You did not mention what board you have. This works on Cyton, but not Ganglion.
Regards, William
Well, actually you could do the external photo trigger on Ganglion, by sacrificing one of the 4 EEG channels, as the trigger channel. In this case you would need a 2 resistor voltage divider network to get the output of the photo chip into a microvolt level signal, for example 50 microvolts.