Keithley 2302 Instruction Manual page 99

Figure 4-1
Steady state for waveforms
based on low pulse times
Integration time
The integration time period can be set automatically or manually by the user. The integration
time can be as long as 60 seconds. For 60Hz power line frequency, the minimum integration time
setting is 850msec. For 50Hz power line frequency, the minimum integration setting is 840msec.
Use AUTO TIME when you want to perform a long integration measurement of each pulse.
When the AUTO TIME operation is performed, the instrument measures the time between two
rising pulse edges and sets an appropriate integration time that will encompass the high and low
periods of the pulse. This integration time applies for all subsequent long integration measure-
ments until another AUTO TIME is performed or the time is changed manually.
If you want the integration period to encompass two or more pulses, you will have to set the
integration time manually. However, you must make sure that the integration time covers only
the portion of the pulse you want to measure. For example, if you want a long integration of two
pulses, you must make sure that the set integration time does not extend into the third pulse.
Trigger edge
A pulse edge can be used to trigger the start of the measurement. Either a rising or a falling
pulse edge can start the measurement. A pulse has to be detected before a rising or falling pulse
edge can trigger a long integration measurement. All pulses that are less than the specified
trigger level are ignored
integration is in process.
A third option is available if you do not want measurements controlled by pulse edges. With
NEITHER selected, measurements start as soon as the long integration function is selected. This
option does not need a valid trigger level to generate a reading. It will perform a measurement
and produce a reading of the current even if a pulse is not present. Therefore, with NEITHER
selected, the NO PULSE message will not appear on the display.
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t > 200ms
low
Steady
state
(see "Trigger level" on page
Long Integration Measurements
t < 200ms
low
Steady
state
4-4). Pulse edges are ignored while a long
4-3