FAQs from Rohde & Schwarz

The measurement range does not fit using a sensor



I set up my HMC8015 for current measurements using a shunt.

I do not understand why the calculated current range does not fit to my settings.

I performed all the settings in the [EXT] - (Sensor) menu and would expect it to calculate a maximum current of 4 V / 100 mOhm = 40 A.

However, it shows 13.3 A. What is the reason for this behavior?



The displayed current is RMS based, while your calculation example only covers peak values.

The HMC8015 allows to set two different values for the crest factor:


In terms of current the crest factor k(c) is calculated using the peak value I(p) and the RMS value I(rms):

k(c) = I(p) / I(rms)

In other words: When the measurement range is based on a crest factor k(c) = 3 and the peak value I(p) is 40 A, the

RMS value I(rms) is

I(rms) = I(p) / k(c) = 40 A / 3 = 13.33 A