What exactly is contained in "Components Level" output of Harmonic distortion Analyzer VI?

[Xooch]

The Components Level output of the Harmonic Distortion Analyzer VI is described in the help file:

"components level contains the array of amplitudes of the measured harmonics in volts if the signal in is in volts. The array index is the harmonic number including 0 (DC), 1 (fundamental), 2 (second harmonic),... n (nth harmonic), up to and including the highest harmonic."

However, why is there more than one measurement of each harmonic included in the array? Specifically, probing the wire says it's a 1D array of clusters with one element each, the clusters are 1D array of doubles.

So, multiple double values are associate with each harmonic. What exactly do these values signify? Creating an indicator on the wire (as below, "component levels" - the indicator is right off the hamonic analyzer, not the bit below it with the index array/unbundle stuff) shows four of the numbers in the array. Sometimes the fourth or even third are greyed out, meaning that the array varies in size from one iteration of my while loop to the next.

I would think that at the least, magnitude and phase would be included, but experimentation with a source that has 60Hz, plus a harmonic (7th, or 15th, etc) at -20 degrees doesnt' correlate with the data. I don't see "-20" or the radian equivilant at all.

Any ideas or a pointer to more detailed information than the help file?

[Dave-C]

Hi Xooch,

I'm not sure that I totally understand what you're asking about.  When I went to recreate this, I used both a cluster indicator and a double array that had been indexed and unbundled from the original output.  

What do you mean by "multiple double values"? I only saw one value for each harmonic, so I'd like to clarify that.

I'd also like to clarify what types of values are being passed into the function and how many channels are being used.  I think these answers may be helpful in finding out what's going on with the cluster greying out some of the values.  I'd also like to verify that these values are being greyed out while the VI is running through different iterations of the loop as opposed to when the program has stopped and restarted.

Thanks,

-Dave C

[Xooch]

Unfortunately I don't have the time today to thoroughly answer every question in your reply, but I will attemp to soon.

As far as the greying out of the indicator - it happens while it's running. It is as if each iteration is changing the size of the arrays that are being output from the Harmonics VI. It's not shown above, but the whole thing is contained in a while loop. I am only aquiring a single channel of data from an NI9225.

[Dave-C]

Hi Xooch,

Could you try attaching a constant or control to the Harmonic Analyzer vi's "Highest Harmonic" input?  When I did it was defaulted to 19, and my array showed all of these values consistently when I tried to replicate the issue.  I would think that this will at least keep your array a constant size.

Regards,

Dave C