Figure 3.
Internal triggering.
(1) Frequency Mode. Channel A accepts input frequencies from 50 uHz
to 500 MHz providing direct readout. These frequencies are counted directly
with no prescaling techniques applied.
Extended frequency capability is
available with the use of plug-ins.
The measurement time is the selected
gate time plus the time until the next trigger pulse occurs. For example,
if the selected gate time is 1 ms, the event gate will close on the next
trigger pulse after 1 ms has elapsed. If the input frequency were 20 kHz
(.05 ms period), the measurement time would be 1 ms + .05 ms = 1.05 ms. The
difference encountered does not affect the accuracy of the measurement.
(2) Period Modes.
Two modes of period measurements are provided:
single period and period average.
These modes are described in the
following paragraphs.
(a) Single Period.
Single period measurements are made with the
GATE TIME switch set to MIN. In this position, the gate time is one period
or 50 ns, whichever is greater. Therefore, the input frequency range for a
single period measurement is 50 uHz to 20 MHz.
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