Trigger Menu Trigger Basics; Trigger Basics - HP 54710A User's Reference Manual

Trigger Menu

Trigger Basics

Trigger Basics
A trigger event is defined as an edge of a selected slope (either positive or
negative) that transitions through a selected voltage (trigger level). This is
referred to as the edge trigger mode. Events leading up to the trigger event
are referred to as occurring in negative time, and events that occur after the
trigger event are referred to as occurring in positive time.
Additional trigger features are added, like logic triggering and holdoff, that
allow you to further qualify the trigger event. The logic trigger modes are
pattern, state, delay by time, and delay by events. Basically you can think of
the logic trigger features as adding a 4-bit logic analyzer to your oscilloscope.
The edge trigger mode looks at only one channel, logic triggering allows you
to qualify the trigger across all of the available trigger sources. Rather than
clutter up the waveform record with useless data that you have to shift
through, you can use logic triggering to pick out the area of the signal you are
most interested in viewing. Then, you can use time base delay to view what
happened before and after the trigger event.
Although previous digital oscilloscopes offer you logic triggering, this
oscilloscope has an added feature that allows you to adjust the trigger level
on each trigger source from within any of the logic trigger softkey menus.
The trigger circuit and sampler circuit operate in parallel. The sampler
samples the input signal at a specific rate. The trigger circuit operates
independently of the sampler circuit, and a trigger event does not have to
occur at the same time as a sample point. Because the oscilloscope knows
when the trigger event happened in relation to the sampled data, the
oscilloscope knows where to place the sampled data on the display.
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