Can you crop a reference waveform?

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Joined: Mon Nov 15, 2021 7:16 pm

Can you crop a reference waveform?

Post by wayneft »

Is it possible to crop a specific section (or zoomed area) of a waveform or existing reference waveform to make a new reference waveform? There are times when we are monitoring a waveform and would like to just zoom in on a section of the waveform and create a reference. We'd prefer not to have all the data both before and after the "zoomed area".

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Joined: Mon Aug 11, 2014 11:14 am

Re: Can you crop a reference waveform?

Post by Gerry »

Hi wayneft,

Sorry for the delayed response. I haven't been able to check the Forum for a while, and I had to find some time to work this one out.

If you still want a solution for this, then the answer to your question is yes, you can crop a Zoomed Area, to make a new Reference Waveform. You can do this using a Math Channel, that I created, as follows:
( ( sign( -( T - Zoomed Area Start Time )( T - Zoomed Area Finish Time ) ) * Channel ) + Channel ) / 2

So, what you need to do is,
(1) Position the Time rulers to the Start and End of the zoomed area and make a note of the start and end times that are shown in the 'Rulers' box, in seconds, including the polarity (e.g., -0.0047 for -4.7ms).
(2) Create a new Math Channel and copy the Math Channel formula, above, into it.
(3) Copy and paste the values, that you made a note of, into the Math Channel place holders for the Zoomed Area, and enter the Channel letter for the data that you want into the 2 other place holders.
(4) Complete the creation of the Math Channel, and then create the Reference Waveform by selecting the Math Channel you just created.

There is also a GIF file showing these steps here:
Waveform Time Crop.gif
For convenience:
1/ You can easily position the rulers by moving the first one as far as it will go, to place it at the end of the Zoomed area, and then just clicking on the second ruler (without moving it) to place it at the Start of the zoomed Area).
2/ In the GIF file I am detaching the Notes window, so that I can switch context to and from the Notes Window, to cut and paste the time values using Alt-tab, while the Math Channel creation window is still open.

UPDATE - Sorry forgot to add the data file, so that you can check the results:
Waveform Cropper.psdata
(240.55 KiB) Downloaded 20 times


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