Cyton (not Ganglion), has an External Trigger capability, using 3 additional 'Aux' channels.

In general, the External Trigger method you mention, has the tightest coupling with the EEG data stream because it is sampled and recorded at the same moments (sample rate) as the EEG samples. Any 'ma

You can use another optoisolator. Be sure the specifications match the one used in the External Trigger link. Also possible that the pin numbers differ.

* You say keeping the trigger signal within the biosignal voltage range "helps" the compression. How exactly does it help? What issues might I face if I don't stay within the range?

You can use one of your 4 normal channels to receive the incoming external trigger information. But I would suggest using a voltage divider network to get the trigger into say the zero to 50 microvolt

I need precise time triggers embedded in the EEG data to mark the onset of stimuli. It would be nice to send the trigger directly from the same Arduino which I am using to generate the stimuli.

Look at this page regarding Cyton External Trigger, using an optoisolator:

The sample rate of the Cyton is 250Hz. You can use one of your channels or one of the Aux channels to record a low fidelity version of the audio. This is called an "external trigger" setup.

The 'best' timing synchronization method is with "external trigger" / sync techniques, which have much improved accuracy over the "marker mode" feature in the SDK. As far as I know

Frankly however, I think you would be BETTER OFF, reading out your external triggers in Analog mode than digital. Then your code can confirm that the trigger on/off voltage levels are what you expect.

I'm sorry to bother you. I have pressed the PROG button corresponding to D17 pin manually according to the instructions of the external trigger on the official website, and collected data. At present,

I think we decided to just stop/start the data streaming in place of the trigger, since we are only marking the beginning and end of the stimuli (i.e., the video).

The 'best' timing synchronization method is with "external trigger" / sync techniques, which have much improved accuracy over the "marker mode" feature in the SDK. As far as I know

I have tried similar masks but didn't like them either much. And some are based on complete bad science (Voss 40hz study). But I'm a study participant at Northwestern and their set up works for me. It

Another alternative is to re-record your experiment using an 'external trigger', which delineates your epochs or labels.

it is common to have 'inhibits' which trigger with excessive beta (mind wandering) or delta (sleepiness). The goal of alpha-theta is to have more 'cross-over' situations where the alpha and theta amp

Oh yes, that makes sense. I wonder why I am still seeing interference with just the photoresistor. Analog value Im getting for the trigger is around 800 (aprox 2.5V), I can possibly increase the value

Previously, I emphasized that the optoisolator circuit is needed IF you are connecting external equipment as the trigger. Your pulse generator sounds like such an equipment, did you use the optoisolat

to 0-3.3V), I did two tests: 10mV and 80mV trigger, every 200ms. Those are very low voltages so I shouldn't expect an interference. I was wearing the wet cap. Here are the brain signals (ch1-8) while

Optoisolator is only needed as I mentioned before, if you are connecting another electrical equipment, for isolation from that unit's power supply circuits. If you found previous threads regarding int