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Taking subset from Waveform Graph

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Hello LabVIEWers,

 

I'm trying to take a 2 second portion of a waveform graph that has a 2 and a half minute song file loaded into it. I've scoured forums and other sources on how to properly use Get Waveform Subset, or any other .vi that would accomplish this part of my VI but can't seem to find anything that I can comprehend. 

 

I would like to be able to specify the start time of the Full Waveform that gets loaded into the Partial Waveform Graph, and then have that start time last 2.2 seconds, this way I can expand the waveform and better see what's going on there and in the future, after filtering and smoothing, find peaks and BPM (end goal). But for now I just need a tip on how to get this portion extracted from the Full Waveform. 

 

I'm attaching my VI , though it may not help much because you won't have the .wav file on your computer that I'm using, but you could use your own. I'll attach screen shots too. 

 

There are some redundant parts to this VI because I've been experimenting with a lot of random ideas to try to get this to work. 

 

2019-10-17.png

 

 

 

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Message 1 of 6
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Hi aj,

 

which part of the LabVIEW help for WaveformGetSubset don't you understand?

Did you read the explanation for all inputs of this function - especially those ones you left unwired?

 

And why do you need to use FromDDT ExpressVI on this waveform wire?

Best regards,
GerdW
CLAD expired, using LV2011SP1 + LV2017 (+LV2019 sometimes) on Win7+cRIO
Kudos are welcome Smiley Wink

Message 2 of 6
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Accepted by aj.insight

It looks like you just missed one input on the Get Waveform Subset.  There is a Ring input on the top to choose whether the times are in samples (default) or relative time.  You just need to set that to Relative Time.


GCentral
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Message 3 of 6
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GerdW,

 

Thanks for the reply, so it seems I hallucinated a broken wire when I went straight from my array to my waveform input on my GetWaveformSubset.vi. Not sure why but I definitely remember having to make a conversion just to get rid of the broken wire, despite the fact that the data form in the context help matched the data output from my array. I received the tip, now I'll get moving with the next step!

 

Thanks!

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cross,

 

That's it! Between the ring input and the conversion from DDT, I had a few simple things screwed up. 

 

Thank you! 

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Message 5 of 6
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Hi aj,

 


@aj.insight wrote:

I hallucinated a broken wire when I went straight from my array to my waveform input on my GetWaveformSubset.vi. Not sure why but I definitely remember having to make a conversion just to get rid of the broken wire,


You got a broken wire because you tried to wire an array of waveforms to in input accepting a scalar waveform.

You needed to place an IndexArray function to solve this problem - but not that FromDDT ExpressVI…

Best regards,
GerdW
CLAD expired, using LV2011SP1 + LV2017 (+LV2019 sometimes) on Win7+cRIO
Kudos are welcome Smiley Wink

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