5
CMRR (Common Mode Rejection Ratio)
Common mode voltage is voltage present on both the COM and VOLTAGE input
terminals of a DMM, with respect to ground. CMRR is the DMM's ability to reject
common mode voltage effect that can cause digit rattle or offset in voltage
measurements. This series has a CMRR specifications of >60dB at DC to 60Hz in ACV
function; and >120dB at DC, 50 and 60Hz in DCV function. If neither NMRR nor CMRR
specification is specified, a DMM's performance will be uncertain.
4) OPERATION
DC Voltage, AC Voltage, & Hz Frequency functions
mV function defaults at DC. Press
SELECT
button momentarily to select AC.
Press the
Hz push-button momentarily to activate or to exit Hz.
Note: Input sensitivity varies automatically with function range selected before
activating the Hz function. mV function has the highest (300mV) and the 1000V range
has the lowest (300V). It is recommended to first measure the signal voltage (or
current) level then activate the Hz function in that voltage (or current) range to
automatically set the most appropriate trigger level. You can also press the
RANGE
button momentarily to select another trigger level manually. If the Hz reading becomes
unstable, select lower sensitivity to avoid electrical noise. If the reading shows zero,
select higher sensitivity.
