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Keysight E1412A Digital Multimer User Guide
Measurement Speed and Accuracy Trade-offs
General Guidelines for Increasing Measurement Speed
Decrease Aperture Time or NPLCs
The aperture time or NPLCs (number of power line cycles) is the amount of time
that the input signal is integrated. The smaller the aperture time or NPLCs, the
faster the readings are taken.
A disadvantage to faster aperture times or smaller NPLC settings is increased
noise will be present in the measured values. The most common source of noise
is from AC power sources.
The magnitude of noise from AC power sources in most cases is many millivolts.
If the signal being measured is large enough, then the noise may not be
significant. However, noise becomes a factor if the signal being measured is in
the microvolt range.
Setting the Resolution
The aperture time or NPLC is set as a result of specifying the <
resolution
>
parameter in the
MEASure
or
CONFigure
command, or by directly setting it with
the
[SENSe:]FREQuency:APERture
or
[SENSe:]PERiod:APERture
command or
[SENSe:]
function
:NPLC
commands.
Store the Readings in Multimeter RAM Instead of Sending them Directly
to the Computer
There is a major difference between
INIT;:FETCh?
and
READ?
after a
CONFigure
command.
INIT;:FETCH?
When the
INITiate
command is sent to the E1412A, the multimeter will store up
to 512 readings in Multimeter RAM. For example:
CONF:VOLT:DC
SAMP:COUN 200
INIT
! Stores 200 readings in RAM
FETC?
! Transfers readings to output buffer
The E1412A then takes the readings as soon as its trigger conditions have been
satisfied and stores them in internal memory (RAM). For example, if the trigger
source is
IMMediate
, the readings are started once
INITiate
is executed. If the
trigger source is
EXT
, then the readings are started when an external trigger is
received.
The
FETCh?
command causes the readings that have been stored in the
multimeter RAM to be placed in the multimeter's output buffer so they can be
retrieved and sent over the GPIB bus (or other I/O interface such as VXLink). No
Summary of Contents for E1412A
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