112 34410A/11A/L4411A User’s Guide
4 Measurement Tutorial
Other Primary Measurement Functions
Frequency and Period Measurement Errors
The multimeter uses a reciprocal counting technique to measure frequency
and period. This method generates constant measurement resolution for any
input frequency. The multimeter's ac voltage measurement section performs
input signal conditioning. All frequency counters are susceptible to errors
when measuring low–voltage, low–frequency signals. The effects of both
internal noise and external noise pickup are critical when measuring "slow"
signals. The error is inversely proportional to frequency. Measurement errors
also occur if you attempt to measure the frequency (or period) of an input
following a dc offset voltage change. You must allow the multimeter's input dc
blocking capacitor to fully settle before making frequency measurements.
DC Current Measurements
When you connect the multimeter in series with a test circuit to measure
current, a measurement error is introduced. The error is caused by the
multimeter's series burden voltage. A voltage is developed across the wiring
resistance and current shunt resistance of the multimeter, as shown below.
UG_ED5.book Page 112 Thursday, March 1, 2012 11:28 AM
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