LabVIEW
Measure Frequency and Amplitude from Analog Signal
Seeing the milli "m" is a bad sign that things aren't working then. 
--- I'm afraid so.
Would it be better to attach a DBL array than building my own waveform or would both methods be the same?
--- Don't know that there is a "better" way. The waveform is a bit cleaner, since everything is in one wire, and the answers come directly out, but it's not a big deal either way.
There must be something you're missing; it's just not that complicated. Either post your code so I can see it, or take a look at this pic:
With a sample rate of 1000, the "dT" is 1/1000 second.
With a sample rate of 1000, then 2000 samples with 36 cycles is equal to 18 Hz.
If you build a waveform and analyze it, you get 1.5 V at 18 Hz.
If you feed the DBL array directly, you must mutiply the frequency detected by the sample rate, and you get 1.5 V at 18 Hz.
Notice the coercion dot on the lower EXTRACT function. That means it is converting the [DBL] array you give it to a waveform for internal use. Probably not a huge deal, but that takes time.
If you make it work on computer generated data, but it doesn't work on your acquired data, then something's wrong with your acquisition.
For diagnostic purposes, graph your data. Display the dT you're building the waveform with. Display the waveform before it goes to the EXTRACT function.
LabVIEW's great for that - just plop an indicator at any point in the chain and see what shows up. Use PROBEs for shorter-term peeking around.
