Auto Mode; Normal Mode - Agilent Technologies InfiniiVision 5000 Series User Manual

Auto Mode

Normal Mode

InfiniiVision Oscilloscopes User's Guide
Use the auto trigger modes for signals other than low-repetitive-rate signals and for
unknown signal levels. To display a DC signal, you must use auto trigger mode since there
are no edges on which to trigger.
When you select [Run], the oscilloscope operates by first filling the pre-trigger buffer. It
starts searching for a trigger after the pre-trigger buffer is filled, and continues to flow
data through this buffer while it searches for the trigger. While searching for the trigger,
the oscilloscope overflows the pre-trigger buffer; the first data put into the buffer is the
first pushed out (FIFO). When a trigger is found, the pre-trigger buffer will contain the
events that occurred just before the trigger. If no trigger is found, the oscilloscope
generates a trigger and displays the data as though a trigger had occurred. In this case,
the background of the Auto indicator at the top of the display will flash, and the Auto
indicator will change to Auto? indicating that the oscilloscope is forcing triggers.
When you press the [Single] key, the oscilloscope will fill pre-trigger buffer memory, and
continue flowing data through the pre-trigger buffer until the auto trigger overrides the
searching and forces a trigger. At the end of the trace, the oscilloscope will stop and
display the results.
Use Normal trigger mode for low repetitive-rate signals or when Auto trigger is not
required.
In Normal mode the oscilloscope must fill the pre-trigger buffer with data before it will
begin searching for a trigger event. The trigger mode indicator on the status line flashes
Trig'd? to indicate the oscilloscope is filling the pre-trigger buffer. While searching for the
trigger, the oscilloscope overflows the pre-trigger buffer; the first data put into the buffer
is the first pushed out (FIFO).
When the trigger event is found, the oscilloscope will fill the post-trigger buffer and
display the acquisition memory. The trigger mode indicator on the status line indicates
Trig'd (not flashing). If the acquisition was initiated by [Run/Stop], the process repeats.
If the acquisition was initiated by pressing [Single], then the acquisition stops and you
can Pan and Zoom the waveform.
In either Auto or Normal mode, the trigger may be missed completely under certain
conditions. This is because the oscilloscope will not recognize a trigger event until the
pre-trigger buffer is full. Suppose you set the Time/Div knob to a slow sweep speed, such
as 500 ms/div. If the trigger condition occurs before the oscilloscope has filled the
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Triggering
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