[DCPower] Perform multiple measurements with sequence output

[Basjong53]

I want to output a continuous sine waveform using a PXIe 4139. I then want to measure back x periods, n times. The n waveforms will then be averaged to reduce the noise.

Example of measuring 4 periods, 5 times.

I set the sequence output as a single period, with repeated output. But how can I measure back exactly n periods? There should be a trigger of some sorts when a new sequence (i.e. a new period) is being output. But I don't find it in the list of the "input terminal" list in the configure measure trigger vi.

I tried to trigger on the source complete event (i.e. start of the sequence) and then measure back the same number of sample as the output samples for a single period. But the problem here is that the even though I set the same value for "Aperture Time" and "Sequence Step dt", after committing the values, they are often different! causing a desynch of output and input.

 

What's the best way to do this? It's fine if (in the above example) I measure 4 periods, miss the 5th, and then measure the next 4.

[santo_13]

If you're generating exactly x samples or steps, you would know how many steps form a period or cycle.

Now, if you have 1 or y measurements per step, you can split the overall data to back track and extract the n cycles of interest.

[Basjong53]

As I mentioned, often the output rate is different from the input rate. Meaning that the number of sample I generate per period isn't the same as the number of samples I should measure per period.