Outputted signal's amplitude different from user inputted amplitude.

[avaughn]

Hi,

I'm currently working on developing a system using the PCI-6110 and BNC-2110.  I'm testing my LabVIEW code by sending a simple sine-wave, but I noticed that something is multiplying the inputted amplitude by a factor of 2.  For example, the amplitude of the signal being sent from LabVIEW is 1, but the signal on the the oscilloscope is reading 2 V p-p.  Likewise, reading in a sine-wave signal with an amplitude of 1 V p-p from a function generator reads in a signal that is .5 V p-p in LabVIEW.  This holds true when using MAX instead of LabVIEW. 

I am assuming this is a hardware issue since it's happening when either using LabVIEW or MAX, but I'm honestly not sure and have no idea where this change in amplitude is coming from.

Thank you in advance,

Amy

[Cavarval · Accepted solution]

Hello,

If you set the card in the Test Panel to generate an amplitude of 1 V, it is actually +/- 1 V (2 Vp-p). This is the same if you generate a sinewave in LabVIEW with the Basic Function Generator.vi (or equivalent). That seems to explain the reading in the oscilloscope. However, I am not sure bout the function generator. Can you provide screenshots of what you are seeing? Do you have different results while measuring the function generator's output with the PCI-6110 and the oscilloscope?

Regards,

[avaughn]

Oh man, I didn't realize that's how amplitude works with the LabVIEW's function generator.  That's a simple solution.  As for the other problem, it's working fine now.  I'm a bit embarrassed to admit, but in my tired state yesterday, I set the amplitude of my signal to the wrong value and just assumed the hardware was processing it weird.  Thank you.