HP 34970A User Manual page 102

Chapter 4 Features and Functions
General Measurement Configuration
Custom A/D Integration Time
Integration time is the period of time that the instrument'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).
Integration time is specified in number of power line cycles ( PLC s).
Select from 0.02, 0.2, 1, 2, 10, 20, 100, or 200 power line cycles.
The default is 1 PLC.
Only the integral number of power line cycles (1, 2, 10, 20, 100, or
200 PLC s) provide normal mode (line frequency noise) rejection.
You can also specify integration time directly in seconds (this is
called aperture time). Select a value between 400 s and 4 seconds,
with 10 s resolution.
For temperature measurements, the integration time is fixed at
1 PLC .
The only way to control the reading rate for ac measurements is by
changing the channel delay (see page 88) or by setting the ac filter
to the highest frequency limit (see page 114).
The specified integration time is used for all measurements on the
selected channel. If you have applied Mx+B scaling or have assigned
alarms to the selected channel, those measurements are also made
using the specified integration time. Measurements taken during the
Monitor function also use the specified integration time.
The following table shows the relationship between integration time,
measurement resolution, number of digits, and number of bits.
Integration Time
0.02 PLC < 0.0001 x Range
< 0.00001 x Range
0.2 PLC
1 PLC < 0.000003 x Range
2 PLC < 0.0000022 x Range
< 0.000001 x Range
10 PLC
20 PLC < 0.0000008 x Range
100 PLC < 0.0000003 x Range
< 0.00000022 x Range
200 PLC
Resolution Digits
4 Digits
1
2
5 1 Digits
2
5 Digits
1
2
6 Digits
1
2
6 Digits
1
2
6 1 Digits
2
6 Digits
1
2
6 Digits
1
2
4
Bits
15
18
20
21
24
25
26
26
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