Keysight Technologies 3458A Guide D'utilisation page 100

3 Configuring for Measurements
Analog RMS conversion
The analog RMS conversion directly integrates the input signal and is the method
selected when power is applied. This method works well for measuring signals in
the frequency range of 10 Hz to 2 MHz and can provide the fastest reading rate of
the three methods.
Random sampling conversion
The random sampling conversion takes numerous samples of the input signal for
each reading generated. Samples are spaced randomly by an internal time base
generator and the signal's true RMS value is calculated statistically. Random
sampling does not require a repetitive input signal (as does synchronous
sampling) making it suitable for applications such as wideband noise
measurements. This method has excellent linearity, good accuracy, and is
particularly suited to low-level (<1/10 of full scale) measurements. The
measurement bandwidth for random sampling is 20 Hz to 10 MHz.
Specifying the AC voltage method
When power is applied, the multimeter selects the analog RMS conversion. In the
power-on state, you can make measurements using the analog RMS conversion
simply by selecting AC or AC+DC voltage measurements as follows:
OUTPUT 722;"ACV"
!SELECTS AC-COUPLED AC VOLTAGE MEASUREMENTS
or
OUTPUT 722; "ACDCV"
!SELECTS DC-COUPLED AC VOLTAGE MEASUREMENTS
The SETACV command allows you to specify the AC voltage measurement
method. For example, to specify the random sampling conversion, send:
OUTPUT 722;"SETACV RNDM"
To select the synchronous sampling conversion, send:
OUTPUT 722;"SETACV SYNC"
To return to the analog RMS conversion, send:
OUTPUT 722;"SETACV ANA"
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important to consider since the combined AC and DC voltage levels may cause
an overload condition even though the AC voltage alone normally would not.
Keysight 3458A User's Guide