Doc, I would like to be able to do math analysis on the data, primarily getting the frequency at any point in time. It will vary between 0 and 300hz. I'd say a vertical resolution of about 30 steps would be adequate.Grumpy_Mike, so if I have a source at +1v, that fluctuates by 0.01v, and I use a voltage divider to bring that down to 0.02v. Then set my ref voltage to 0.03v. Does that mean that I will be able to measure the fluctuations at a resolution of 0.00003v? I think my theory is right, the question is how will it work in practice? How low can my ref voltage go with decent output?