Agilent Technologies 93000 SOC Series Training Manual page 491

Lesson 2 – TIA Setup
Start Count and Stop Count
With the Start Count and Stop Count parameters, you can delay
the start and the stop of a measurement.
For example, if you have a measurement that is specified to start
from a rising edge on channel 1, and you have entered a Start
Count of 6, the measurement will not start on the first rising edge
on channel 1 after arming. Instead it will start on the 6th rising
edge on channel 1.
The Stop Count delay defers the stop of a time measurement in
the same way.
The Stop Count is typically used when performing a frequency
(FREQ) measurement. When specifying a Stop Count >1, the
frequency gets measured over several periods to achieve a more
accurate result than with a single period measurement.
The TIA will automatically calculate the correct frequency from
such a measurement over several signal periods, as shown in the
following figure.
Using the Stop Count for Frequency Measurements
Arming for Repeated Measurements
If you repeat a measurement several times (by specifying a Sample
Size >1 in the Measurement settings), you must provide the
appropriate arming which is different for the two types of arming
sources EXTERNAL and AUTO. Repeated measurements of periods
that are not averaged are, for example, required to determine the
jitter.
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