Persistence - HP 54710A User's Reference Manual

Display Menu

Persistence

Persistence
Persistence is a display function that determines how long a data point is
kept on the display before the oscilloscope erases it from the display.
You can have averaging and persistence on at the same time because when
averaging is on, the averaging is done before the data is sent to the display.
Averaging is controlled by the acquisition menu.
Variable
By selecting variable persistence, you can vary the persistence time from
minimum to 40 s. When the persistence is set to minimum, all the displayed
data points are kept on the display for one time base sweep. With the next
time base sweep, all the previous data points are erased from the display, and
new data points are written to the display. As you increase the persistence
time, the previous data points are kept on the display depending on the
persistence time you have selected. Therefore, the longer the persistence
time, the longer each data point is left on the display before it is erased from
the display. You can change the persistence time with the knob, arrow keys,
or keypad.
The variable persistence mode has a feature called gray scaling. On older
digitizing oscilloscopes, pixels were either turned on to full brightness or
turned off. This gave you no feeling for how frequently events happened. In
contrast, the relative brightness of a trace on analog oscilloscopes told you
the frequency of occurrence of events, but you usually used a viewing hood
to see the extremely dim trace. With gray scaling, the brightness of the pixel
fades though up to eight levels of intensity, and the brightness of a pixel only
depends on how often it is illuminated by acquired data points.
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