What the Eagle™ Records
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The waveform data for the previous cycle is also recorded, to
provide a pre-trigger waveform. The user can also customize how
many pre and post waveform cycles are recorded. Whenever a
waveform is triggered, all voltage and current wave shapes are
recorded, regardless of which channel caused the trigger. The
waveforms of the next cycle are also recorded, to provide a post
trigger waveform. This creates a three-cycle waveform capture
record. Many users choose to record two cycles prior to the
triggering cycle and six cycles after the triggering cycle, recording
nine cycles total (including the triggering cycle). This provides a
good depiction of what happened just before the triggering cycle
and what happened immediately after. If the trigger condition is
met again on the next cycle, then an additional cycle of waveforms
is added. In general, the waveform capture record continues until
waveform capture one cycle after the triggering stops. If the
voltage is fluctuating wildly, the entire waveform capture memory
could be filled by a very long waveform capture record. If the
waveform capture memory is full before the end of the event and
the unit is in wrap-around mode, the Eagle automatically erases
cycles of the earliest record to make room for the new data. If the
unit is not in wrap-around mode, it will not record any waveforms
for events occurring after the waveform capture memory has been
filled.
The waveform data is presented as a graph and a report. The
report is usually used only if the data will be exported to a
spreadsheet.
Typical Settings and Suggested Uses
The default setting for triggering a voltage waveform capture is
3%. With this threshold, the RMS voltage has to change by at
least 3% in a single cycle. If the threshold is too tight, waveform
capture will trigger so often that useless events overwrite the
important waveforms. You may also choose to trigger a waveform
capture using a voltage value, rather than a percentage. The
default trigger setting for the voltage is 5 volts. In order to use
this, simply set the percentage setting for waveform capture
higher than the voltage setting. For example, if you would like the
trigger threshold to be 5 volts rather than 3%, simply set the
percentage trigger threshold to a value such as 100%, and the
waveform capture will then be triggered by the threshold of 5 volts,
as that is the tighter constraint.