Specifications

4.1.2 True RMS AC Voltage Measurements
ACV is specified for signals greater than 1mV, from 10 Hz to 100 kHz. The ACV function is AC coupled, and
measures the true RMS value of the waveform. As with virtually all true-RMS measuring meters, the SMX2040
may not read a perfect zero with a shorted input. This is normal.
ACV measurements, if possible, should have the NEUTRAL or GROUND attached to the SMX2040 V,Ω -
terminal. See Figure 4-1, below. This prevents any “Common Mode” problems from occurring (Common Mode
refers to floating the SMX2040 V,Ω LO above Earth Ground.) Common Mode problems can result in noisy
readings, or even cause the computer to hang-up under high V x Hz input conditions. In many systems, grounding
the source to be measured at Earth Ground (being certain to avoid any ground loops) can give better results.
Figure 4-1. Make Voltage measurements with the source ground attached to the SMX2040 V,Ω - to
minimize “Common Mode” measurement problems.
4.1.3 AC Peak-to-Peak and Crest Factor Measurement (SMX2044)
Measurement of Peak-to-Peak, Crest Factor and AC Median values requires a repetitive waveform between 30 Hz
and 100 kHz. The DMM must be in AC voltage measurement mode, with the appropriate range selected. Knowing
the Peak-to-Peak value of the waveform is useful for setting the Threshold DAC (described below). This latter
function is a composite function, and may take over 10 seconds to perform.
25 Signametrics
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com