How to synchronize an analog output and an digital output channel?

[Fuh]

Dear Labview experts:

I am currently using Labview 8.0 and a multifunction DAQCard 6062E.  I am an EEG (electroencephalogram) person and I need to generate sounds and record EEG data.  My question in Labview programming is: when I send out the first data point of sounds through an AO channel, I need to send out a trigger (preferrably through digital output lines) to the recording system, so that the recording system knows exactly (or as close as possible) at what data point (of the recorded data points) that the sound was sent out through the AO channel.  I have written three VIs.  One to generate sounds through an AO channel, one to generate triggers through a digital port (consists of 4 digital output lines), and another one to record EEG data.  The three VIs work fine separately, but what shall I do in order to synchronize the AO channel and the digital output port? 

Any comments or inputs would be very much appreciated.

Sincerely,

Fuh

[Steve.J]

One very simple solution is to record the sound (or signal derived from the sound) along with the EEG data on an extra channel.  This guarantees that you are truly synchronized and doesn't require any special programming.  You can also post-process the EEG data by searching for the signal on this extra channels and aligning the records (I'm assuming that you will be doing some signal averaging, etc.).  Since the stimulus signal is part of the EEG record, you can't ever lose the trigger/sync signal.

Steve

[PBear]

Hi Fuh,

I would recommend creating an AO task and use the export signals VI to send the internal start trigger out to one of your PFI lines. This will create a TTL pulse on whichever PFI line you specify at the moment the task is started.

Message Edited by PBear on 06-18-2008 04:39 PM

[Fuh]

Thank you so much for your invaluable comments.  I will go ahead and try those.

Best,
Fuh

[orchid]

Hi Fuh,

I am using Labview 7.1 with vista and USB6009. I am gonna record the EEG signal and display it on the Labview. But, I do not know how to do it. Can you help me?

Thanks,

Orchid (cruel_orchid@yahoo.com)

[PBear]

Hi Orchid,

Since this thread is about a different topic that has been solved, I would recommend starting a new thread under the Multifunction DAQ forum. This way you can get the fastest response from frequent viewers. Thanks and have a great day.