10-21-2014 04:42 PM
Hello,
I've been struggling with what should be ostensibly a simple problem. First off, I am working with DaqMXBase (3.7) on a Macintosh-- I realize this limits my options for potential solutions, however my goal is to construct a cross-platform solution for field research.
I am building a signal recorder for electric fish-- these fishes produce intermittent voltage pulses over time (~10ms or so, about the length of an action potential for those neuro nerds out there!). I would like to record the waveform of a single pulse, which varies by species. I have built most of the VI as a state machine in LabView, but have been struggling with how to implement a very simple software trigger to capture these waveforms.
I've set up aqcuisition succesfully of N points ('live data mode'), but what I'd like to do is set a level threshold in this window (at the amplitude of the electric fish signal), and capture a window of n/2 points on either side of the signal where it crosses this threshold. Seems simple enough, perhaps one of the wise members of the boards can help?
Best,
Jason Gallant
10-22-2014 02:07 PM - edited 10-22-2014 02:07 PM
This sounds like you might want to look into Pretriggered Acquisition. Here is a link with some more information on Data Acquisition Triggering: http://www.ni.com/white-paper/4329/en
Section 4B might be useful for you. This is for DAQmx however, so support on this might be limited in DAQmx Base.