Waveform Distortion after Multiplication?

Hi all,
Newbie on the line here. I wrote a VI that obtains the reading of channels 1 and 2 from an oscilloscope via GPIB. The readings come out to be decent looking sinusoids when plotted on a waveform graph. However, after multiplying the two, the product is quite distorted and looks nothing like what you would expect. The waveform of the product contains huge jumps from negative to positive values even when outputs #1 and #2 are very continuous. I've also noticed that if you adjust the scaling on the oscilloscope to a certain value, the distortion goes away and the product looks like a normal sinusoid as well. At all other scaling values, the product waveform is distorted. Since the output wires of channels 1 and 2 (to the individual plots) are from the same branch as those going into the multiplication block, I'm wondering how this would make sense. Anyone have an idea?
The output graphs are attached as the following. Much thanks in advance for the help.
Attachments:
waveforms_decent.JPG ‏96 KB
waveforms_notgood.JPG ‏107 KB
block.JPG ‏109 KB

What data type are you type casting too?  If it is I8, you are getting overflow when multiplying.  I'm looking at graph time 60.  One curve has a value of 10 and the other has a value of 24 at T-60.  The product would be 240.  Yet on the power graph at T-60, the value is a negative number.  If you are type casting to an I8, I would believe the result would be negative since I8 range is from -128 to 127.  240 would fall into the negative range in this case.  If this is the case, type case to U16 to prevent overflow.
- tbob
Inventor of the WORM Global

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