Owner`s manual

48
USING THE DVM
The following applications describe how to make basic
voltage measurements using the ProbeScope’s digital
voltmeter (DVM) mode. These applications are not de-
scribed in detail, but are designed to familiarize you
with basic DVM operating techniques.
In digital voltmeter measurements, the measured AC
or DC voltage is converted to digital values using an
analog-to-digital (A/D) converter.
In the AC mode, the ProbeScope rectifies the AC signal
to convert it to DC. The DC is then converted to a digital
value by a 6-bit resolution A/D converter, then multi-
plied by 0.707 to display the RMS value. You must
have at least two cycles of a waveform for the Probe-
Scope to accurately measure AC DVM values.
Note
: The voltmeter function is to be used only for pure
AC and DC measurements. Only sine waves are al-
lowed for AC measurements since the ProbeScope
does not support true RMS functions. For measuring
an AC signal on a DC bias, use the oscilloscope (see
“Using the Oscilloscope” on Page 22).
In the DC mode, the DC is directly converted to a digital
value by the 6-bit resolution A/D converter. An average
of up to 128 recorded values appears on the screen. A
negative value is displayed when the average is below
the reference line.
Follow these steps to measure a signal’s voltage level.
1. Continuously press the Menu button until the
FUNCTION
mode appears on the display.
2. Press the Select button to set the function mode
to
DVM,
then press the Menu button again.
22-310.fm Page 48 Friday, August 6, 1999 12:26 PM