HP 54710A User's Reference Manual page 147

Display Menu
Persistence
Gray scaling lets you see how frequently an event is happening. The most
frequently occurring events tend to be brighter than less frequently occurring
events. Gray scaling is more visible with a low persistence time, about
100 ms to 800 ms, and with dynamic signals. You can use gray scaling on
PRBS signals (pseudo random bit sequence) or frequency modulated signals.
A minimum persistence setting is used when the input signal is changing and
you need immediate feedback. For example, if you are rapidly probing from
point to point, or you are setting the amplitude or frequency of a signal
source, you may find that more persistence is useful for observing long-term
changes in a signal or observing signals with low repetition rates.
Because all of the data points acquired from a specific trigger event are
displayed at the same intensity, the gray scaling feature gives you several
benefits that are listed below:
•
You can associate various points on the display to determine which points
make up individual waveforms.
•
You can determine the relative ages of waveforms.
•
You can determine the direction in which a waveform is changing.
•
You can determine the value of a waveform inside of a waveform envelope.
Infinite
When you select infinite persistence, all the data points are kept on the
display until you press the Clear display key, the Autoscale key, change the
vertical settings, change the horizontal settings, change the trigger settings,
or until you turn off the oscilloscope. You can use infinite persistence for
worst-case characterization of signal noise, jitter, drift, and timing.
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