HP 34970A Custom A/D Integration Time

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 (PLCs). 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 PLCs) 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 μs and 4 seconds,
	with 10 μs resolution.	4
∙	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	Resolution	Digits		Bits
0.02 PLC	< 0.0001 x Range	41⁄2 Digits		15
0.2 PLC	< 0.00001 x Range	51⁄2 Digits		18
1 PLC	< 0.000003 x Range	51⁄2 Digits		20
2 PLC	< 0.0000022 x Range	61⁄2 Digits		21
10 PLC	< 0.000001 x Range	61⁄2	Digits	24
20 PLC	< 0.0000008 x Range	61⁄2	Digits	25
100 PLC	< 0.0000003 x Range	61⁄2	Digits	26
200 PLC	< 0.00000022 x Range	61⁄2	Digits	26

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