Gain/Offset for NeuroScan SynAmps RT high-level input

[gphilips]

I am currently recording EEG data using BCI2000 and NeuroScan SynAmps RT equipment.

I would like to use an external event marker to synchronize my EEG data files with separate EMG data files. I have the hardware to feed a 5 volt event marker to both systems. I am trying to use one of the two high-level input channels of the SynAmps for this purpose, which seems to be fairly straight forward.

In the Acquire software, I have followed the proper process to configure and add a channel. So the high-level event marker should be recorded alongside the EEG data, as an extra channel.

In BCI2000, I have adjusted the number of channels, channel names, and number of SourceChGain/SourceChOffset entries appropriately. However, I am receiving the usual "LSB" error when I try to run the system, which makes me think that I need to correct the SourceChGain (and possibly offset) value for the high-level channel. I would think that the ADC LSB conversion factor would be different for the high-level channel, but it seems to be the same in the Acquire settings.

Does anyone have experience using the SynAmps RT (or 2) high-level input channel(s) with BCI2000?

Would the NeuroGetParams tool give me the correct settings, despite their matching appearance in the Acquire settings menus?

[gphilips]

Apparently neurogetparams is magical, and it seems to have solved the issue for me.

It decreased the gain on all channels, not just one, by about two orders of magnitude, which is interesting. There may be a difference in scale, but it shouldn't be a problem.