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SPA Measurement Processes
This section introduces you to the measurement processes of the System
Performance Analysis (SPA) software. It tells you how to select the
appropriate trace mode and labels. It also explains how SPA samples and
sorts data.
Selecting and changing trace modes
SPA has three trace modes: State Overview, State Histogram, and Time
Interval. These are selected by the Trace Mode field in the SPA data display.
Only the currently displayed trace mode is affected during an acquisition.
While acquiring and viewing data in one trace mode, the other two trace
modes are not updated. If the trace mode or any other critical variable is
changed during an acquisition, the logic analyzer stops the acquisition and
displays "Warning: Run HALTED due to variable change."
Each trace mode only performs statistics on its own database. Therefore, if
acquisitions are completed in two different trace modes, the two modes will
not contain the same data.
For example, you select the State Overview mode and press the Run key.
After the data accumulates for a period, press Stop. You then select the Time
Interval mode and the screen is blank since no data has been acquired in this
mode. You again press Run and let data accumulate and press Stop. In this
example, two separate data sets are acquired, the first for State Overview
mode, the second for Time Interval. You can now move between the modes
and see the correct data for the associated measurement.
This separate acquisition data applies to all three trace modes. In this way,
three separate views of the target system can be acquired and stored in SPA.
Sampling methods and data sorting
SPA provides a statistical summary of target system behavior over time. The
greater the number of samples, the more accurate the statistics. Therefore,
SPA should always be run in the Repetitive mode. By doing this, the analyzer
will continue to sample the data and update the display until Stop is pressed,
or until a sampling variable is changed on the display.
After SPA completes an acquisition, each sample in the current acquisition is
compared to the ranges or buckets for the current trace mode. If the sample
matches a range or bucket, it is sorted into that range or bucket. This process
is repeated for every sample in the acquisition. After the entire acquisition
The SPA Menu
SPA Measurement Processes
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