BioSemi.nl

Dear all,

I have been using Biosemi for a while, recording visual evoked potentials using Presentation. The triggers were all recorded perfectly for a while but suddently the triggers that I have been recording (with Biosemi) are completely different from the ones I have written in the scenario file (presentation). I have not change anything, at all, and now the trigger value has changed by itself? Has this ever happened to you? The scenario is the same and I have not changed the triggers and the triggers that I read with Biosemi are totally different.

Any help you can provide me would be really appreciated,

thank you,
silvia
New Haven, Yale.

Did the problem start after reducing the sample rate (changed speedmode on the AD-box, or changed decimation ratio in ActiView) ?

Best regards, Coen (BioSemi)

Dear Coen,

Thank you so much for your feedback. I really appreciate it. After spending lots of hours we realized what happened. It turns out that another group that is using the same system (the lab is shared) touched the connections and the connection going to the USB2 Receiver Back got a bit loose....so some of the pins were active and some were not. Therefore I was seing triggers delivered but the numbers were all changed and some of them not even delivered. After plugging back the connection properly we received the trigger values perfectly.

THank you so much for your help,
s