Newtons4th PSM3750 NumetriQ, Startup Manual, Page: 71 / 104

PSM3750 Quick User Guide
Page 69
8.4 RMS – True RMS Voltmeter
The RMS Voltmeter measures the total rms values of the signal present at the
input terminals to the bandwidth of the instrument (<5MHz). Care must be taken
when measuring low signal levels to minimise noise pick up on the input leads.
The RMS Voltmeter measures the following elementary values:
1. Rms
2. Dc
3. Peak
4. Surge
5. Mean
And derives the values: ac, dBm, crest factor and form factor
Figures shown are for illustration
purposes only
The peak measurement is simply the value with the largest magnitude. Positive
and Negative peaks are independently filtered then the result with the largest
magnitude is taken as the peak value.
In order to measure surge conditions, the maximum instantaneous peak value
(unfiltered) is also recorded. It is important that the PSM3750 does not
autorange whilst measuring surge
– either set the range to manual or repeat the
test with ranging set to up only. To reset the maximum press “START”
Crest Factor is derived from peak and rms
cf = peak / rms
Form Factor is derived from the normalised mean and rms
ff = mean / rms