We have been running an experiment trying to collect ABR data using the Brainvision EP-PreAmp and Actichamp system. We ran several successful tests with short versions of our experiment, about 10-15 minutes of recording. We were able to process the data in eeglab and saw the components we were expecting.
We have recently been running our full experiment, recording for about 45-50 minutes. The files are necessarily much bigger. The test .eeg files were ~150mb and the full .eeg files are ~550mb. All of our Brainvision equipment seems to working (amps, batteries, electrodes), and we are able to get our impedances low before recording. However, when we import the vhdr files into eeglab, it looks like there's no data there. We are thinking this might be an eeglab problem - perhaps the file is too large and something's getting lost in the import? Any advice would be greatly appreciated.