HP 54750A, User Manual, Page: 56 / 478

The Instrument at a Glance
The Front Panel
Indicator lights
There are three indicator lights near the top-left corner of the instrument.
These lights give you a quick indication of the acquisition status of the
instrument.
Armed When the armed light is on, it indicates the trigger circuit is armed and
waiting for a valid trigger event to occur . A valid trigger event occurs when a
signal meets the triggering conditions specied in the trigger menu.
T riggered When the triggered light is on, it indicates the instrument accepted a trigger
event. Every time the instrument accepts a trigger event, one data point is
sampled. When enough points have been sampled to ll the record length, a
trace is completed.
The triggered light can be used to help determine the trigger thresholds . T o
do this , simply move the trigger level in either direction. When the triggered
light turns o, you know that is one of the trigger thresholds . Move the
trigger level in the other direction to determine the other threshold. Y ou now
know what the trigger thresholds are and you can set the trigger level as
required by your application.
Typically the trigger level is set halfway between the two thresholds .
Freerun Freerun automatically provides a trigger as soon as the trigger is armed. It is
used to view the input signal when no valid triggers are available .
HP 83480A Option 100 only: When in the 12 GHz mode , the triggered and
freerun lights are illuminated at all times to reect the operation of the 12
GHz trigger .
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