Rigol DM858 - Loading Errors (AC Volts); Table 8.2 Input Resistance at Various Frequencies

Error (Crest factor): crest factor additional error.
Error (Bandwidth): estimated bandwidth error calculated according to the following
formula.
..FC
: indicates the signal crest factor.
F
: indicates the fundamental frequency of pulse
BW
: indicates the effective bandwidth of the multimeter.
Example:
Calculate the approximate measurement error for a pulse train input with a crest
factor of 2 and a fundamental frequency of 20 kHz. Assume the multimeter's 1-year
accuracy specifications: ± (0.05% of reading + 0.03% of range).
Total Error = (0.05% of reading + 0.03% of range) + (0.05% of range) + (0.8% of
reading)
= 0.85% of reading + 0.08% of range
8.3 Loading Errors (AC Volts)
In the AC Voltage function, the input of DM858/DM858E appears as a 1MΩ resistance
in parallel with 100 pF of capacitance. The test lead that you use to connect signals to
the multimeter will also add additional capacitance and loading. Table 8.2 Input
Resistance at Various Frequencies shows the multimeter's approximate input
resistance at various frequencies.
Table 8.2 Input Resistance at Various Frequencies
Input Frequency Input Impedance
100 Hz 1 MΩ
1 kHz 850 kΩ
10 kHz 160 kΩ
100 kHz 16 kΩ
For low frequencies:
Measurement Tutorial
DM858 Series User Guide
122
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