Stanford Research Systems SR785, Operating Manual And Programming Reference

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1-62 Exceedance Statistics
Press [Start/Reset] Start the measurement. This resets the waterfall
buffer. New measurements are added to the
waterfall buffer every 100 ms. The number of
records stored in the waterfall is shown in the
Vertical Scale Bar and increments to 100.
Because the waterfall storage is One Shot, the
waterfall buffer fills once (100 records). No more
records are added after 10 seconds.
7. Press [Analysis]
Select the Analysis menu.
Press <Exceedance Stats> Select the Exceedance Statistics menu.
Press <Stop Index> The exceedance is calculated using the records in
the waterfall buffer starting with the Start Index (0
is the most recent record) and continuing through
the Stop Index (Total Count - 1).
Press [9] [9] [Enter]. Enter 99 to include records 0 through 99 (100
total).
Press [Pause/Cont] Pause the measurement. Exceedance calculation
requires that the active display be paused. This
ensures that the waterfall buffer is static and no
new records will be added during the calculation.
Press <Calculate Excd>, choose (Trace 1) with
the knob and press [Enter]. The exceedance results are stored in a data trace.
The trace measurement is the same type as the
waterfall measurements. In this case, the trace data
for each bin is exceeded by only 1% (Exceedance
Pct) of the records stored in the waterfall buffer.
8. Press [Alt] [Link], choose (Trace 1) with the
knob and press [Enter].
Trace to Ref is an alternate function. The alternate
key functions are labeled below each key (in this
case, the [Link] key).
Trace to Ref copies the data in a trace to the
reference graph of the active display. The reference
graph is shown in half intensity.
In this case, the reference graph is the level of each
octave bin which is exceeded only 1% of the time
(L
1
).
Note that the exceedance is also calculated for the
power bin (L
eq
).