Acquiring raster scan analog voltage data

[ssomnath]

I have attached a schematic of my experimental setup and what I plan to do with the data once it is acquired. I have tried implementing my latest schematic in code and was not able to acquire at > 300 kS/s. I had to switch to TDMS file write. This meant that I cannot look at the raw data once the experiment is complete and I am stuck with humungous amounts of data that I have to post process. I need to acquire a lot of data for downsampling & filtering since the signal is noisy, but I don't need all of the raw data. For example, I may acquire ~ 1 GB of raw data but by the time I am done processing the data, I end up with something like 2-3 MB. I am trying to improve the analog filters I have in my circuit to clean up the data so that I don't have to acquire large amounts of data all the time. 

Is it possible to parse a stream of analog data using digital input pulses as delimiters, filter/decimate the data and place it into a 2D array ready for real-time display and file output? Please le me know if any additional information is required.

[johnsold]

How are the TTL pulses connected to the DAQ device?

I do not know if these will work at the higher speeds, but I can think of two ways to try.

1. Use the TTL pulses as digital triggers for the analog conversion.  Then do a finite acquisition which will take you to the point where you want to discard data at the far end.  Split the array at the near end to discard data.  What is left is the useful data for that scan.

2. Connect the digital pulses to an unused analog channel and convert them jsut like the analog data.  Split off the channel with digital data and use Threshold 1D Array to find the rising edges of the digital pulses.  Then discard the end data as before.

Lynn