Got it Rick. Yes, we discussed this before; for high-fidelity acquisition measurements you will need precise time. You do not want a soft timer for that, but something that queries the hard clock. If you can afford having a process devoted to full-time data acquisition (and you should if you need it), have it making continuous queries to the clock and decide to trigger the acquisition event. With some offline tests and experimentation you can associate a time-scale with the response from the data-acquisition interface such that data is perfectly matched to an objective time. Peg the process to a core and keep it there. There has got to be a lot of work done on this. People do super high frequency measurements with proper hardware, and I am sure somebody out there has pushed the limit of it under some Linux setup.