Why NI Oscilloscope Amplify the Signal When Using NI Signal Generator?

Updated Nov 27, 2022

Reported In

Hardware

  • PXI-5421
  • PXI-5114

Software

  • LabVIEW
  • InstrumentStudio

Issue Details

I am using an NI signal generator to generate a 2Vpp signal. When I read it using an NI oscilloscope, it shows a 4Vpp signal, twice bigger compared to the signal I generate.

Solution

The problem is due to the matching impedance between the NI signal generator and the NI oscilloscope.
You should match the impedances between them. 

By default, the NI signal generator load impedance is 50 Ω, and the NI oscilloscope input impedance is 1 MΩ.

To change the NI oscilloscope input impedance in LabVIEW, use the niScope Configure Chan Characteristics.vi.

NI-Scope- channel impedance on LabVIEW.png

In InstrumentStudio, go to the oscilloscope panel, select the Channel Settings icon and change the Input impedance parameter. 

Input impedance cropped2.png
 

Related Links


 

Other Support Options

Ask the NI Community

Collaborate with other users in our discussion forums



Request Support from an Engineer

A valid service agreement or active software subscription may be required, and support options vary by country.