Keysight E1412A, User'S Manual And Scpi Programming Manual, Page: 45 / 243

Keysight E1412A Digital Multimeter User Guide xlv
Frequency and Period Measurement Errors Keysight E1412A Multimeter Application Information
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 will 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.
Measurement Configuration
This section contains information to help you configure the multimeter for
making measurements. The parameters discussed in this section give you
measurement flexibility when using the
CONFigure command.
AC Signal Filter
The E1412A Multimeter has three different ac filters which enable you to either
optimize low frequency accuracy or achieve faster ac settling times for ac
voltage or ac current measurements. Only these functions use the ac filter.
NOTE: These reading rates account for only the AC filters behavior.
–
The ac filter selection is stored in volatile memory. Default is the medium
filter (20Hz - 300kHz) at power-on or after a module reset.
– The CONFigure and MEASure:<
function
>? commands automatically select
the medium (20Hz) filter.
–
Use the [SENSe:]DETector:BANDwidth 3 | 20 | 200 | MIN | MAX command to
change the ac filter selection following a CONFigure command. The MIN
parameter will select the 3Hz filter and the MAX parameter will select the
200Hz filter.
Table 2-4 AC Signal Filters
AC Voltage or Current
Input Frequency AC Filter
Selected Max Reading Rate for
Adequate Settling
3 Hz to 300 kHz Slow filter 1 reading/7 seconds
20 Hz to 300 kHz Medium filter 1 reading/second
200 Hz to 300 kHz Fast filter 10 readings/second