User`s guide

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100

88 Agilent 34980A Mainframe User’s Guide

3 Features and Functions

Custom A/D Integration Time

Integration time is the period of time the internal DMM’s analog- to- digital

(A/D) converter samples the input signal for a measurement. Integration

time affects the measurement resolution (for better resolution, use a longer

integration time) and measurement speed (for faster measurements, use a

shorter integration time). The default integration time is 1 PLC.

• Integration time is specified in number of power line cycles (PLCs).

Select from 0.02, 0.2, 1, 2, 10, 20, 100, or 200 power line cycles.

• Only integral number of power line cycles (1, 2, 10, 20, 100, or 200

PLCs) provide normal mode (line frequency noise) rejection.

• You can also specify integration time in seconds (this is called aperture

time). Select a value from 300 µs and 1 second, with 4 µs resolution.

• The only way to control the reading rate for ac measurements is by

changing the channel delay (see “Channel Delay” on page 120) or by

setting the ac filter to the highest frequency limit (see “AC Low

Frequency Filter” on page 102).

• The specified integration time is used for all measurements on the

selected channel. If you have applied Mx+B scaling, have assigned

alarms to the selected channel or are using Monitor mode, those

measurements are also made using the specified integration time.

• The following table shows the relationship between integration time,

measurement resolution, number of digits, and number of bits.

• The instrument selects 1 PLC when the measurement function is

changed and after a Factory Reset (

*RST command). An Instrument

Preset (

SYSTem:PRESet command) or Card Reset (SYSTem:CPON

command) does not change the integration time setting.

Front Panel Operation: DMM or Channel (Configure) > INTEGRATION > TIME

First, select the measurement function on the active channel. You are

automatically guided to the next level of the menu where you can select

a specific integration time.

Remote Interface Operation: You can set the integration time using the

SENSe commands. For example, the following command specifies an

aperture time of 2 ms for resistance measurements on channel 2001.

SENS:RES:APER 0.002,(@2001)

Integration Time Resolution Digits Bits

0.02 PLC

0.2 PLC

1 PLC

2 PLC

10 PLC

20 PLC

100 PLC

200 PLC

< 0.0001 x Range

< 0.00001 x Range

< 0.000003 x Range

< 0.0000022 x Range

< 0.000001 x Range

< 0.0000008 x Range

< 0.0000003 x Range

< 0.00000022 x Range

4½ Digits

5½ Digits

6½ Digits