3 Features and Functions
72 Keysight 34420A User’s Guide
– Front Panel operation: Integration time can be set indirectly when you select
the number of digits (see page 54).
You can also set the integration time in the MEASurement menu with the
2: INTEGRATE command.
– Remote operation: Refer to the table on page 144. Use one of the following
commands:
[SENSe:]
VOLT:DC:NPLC {0.02|0.2|1|2|10|20|100|200|MIN|MAX}
FRES|RES
:NPLC {0.02|0.2|1|2|10|20|100|200|MIN|MAX}
TEMP:NPLC {0.02|0.2|1|2|10|20|100|200|MIN|MAX}
Integration time and resolution are related. The CONFigure and MEASure?
commands can also set the integration time, see page 144.
Reducing Measurement Noise
At high resolutions and low measurement levels, measurement noise can become
an important factor in the accuracy of your measurements. One possible source of
measurement noise is the wiring and cabling in the test setup. These noise
sources and their effects are discussed in Chapter 7, "Measurement Tutorial". A
smaller level of noise is also inherent in the meter itself.
To minimize the effects of noise on your measurements, use the highest possible
integration time (NPLC) and average the readings. Faster reading rates are more
susceptible to noise. Choosing the best NPLC and averaging method for your
measurement requires a tradeoff between the reading rate and the level of
acceptable noise in the resulting measurement.
The Integration Time (NPLC) and averaging can be multiplied to create an
equivalent NPLC. The equivalent NPLC defines the reading rate and characterizes
the expected noise level. Averaging can be performed in the meter by using either
the digital filter or by using the statistics (Stats) mode of operation.
Measurement noise characteristics of the meter closely match theoretical
gaussian noise distributions. The graph on the next page shows typical input
Integration Time is local to the selected function. This means that you can select
the integration time for each function independently. The meter remembers the
integration time when you switch between functions.
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