5112 Vamplitude -vs- Vp-p

[bradpopelka]

I have a 5401 arb in a pxi chassis dumping a +/- 1.0 V sine wave directly to a 5112 scope in the same pxi chassis through a coax.  Using the scope function for Vp-p I see 2.125V, using the function for Vamplitude I see 1.925.  What's the difference between the two functions?

brad.popelka@bench.com

[Sean_C.]

Hi Brad,

You can find the difference between these two measurements in the High Speed Digitizers Help under Programming >> Reference >> NI-SCOPE LabVIEW Reference Help >> Scalar Measurements.

The Voltage Peak to Peak measurement is:

"The maximum voltage minus the minimum voltage in volts."

The Voltage Amplitude is:

"The voltage high minus the voltage low in volts. "

Furthermore, you can find the definition for voltage high and voltage low in the same section of the help document.

Voltage High:

"The last-acquisition histogram method is used, where the voltage high result is the voltage of the histogram bin with the maximum number of hits above 60% of the waveform's voltage peak-to-peak value. This calculation is useful for ignoring the overshoot and preshoot on square waves. "

Voltage Low:

"The last-acquisition histogram method is used, where the voltage low result is the voltage of the histogram bin with the maximum number of hits below 40% of the waveform's voltage peak-to-peak value. This calculation is useful for ignoring the overshoot and preshoot on square waves. "

I hope this helps.  Please let me know if you have any further questions.

Regards,
Sean Close

Product Support Engineer: High Speed Digitizers