Technical data

374 Agilent Infiniium 9000 Series Oscilloscopes Programmer's Reference
19 Histogram Commands
The database does not differentiate waveforms from different channels or
functions. If three channels are on and the waveform from each channel
happens to light the same pixel at the same time, the counter is
incremented by three. However, it is not possible to tell how many hits
came from each waveform. To separate waveforms, you can position the
waveforms vertically with the channel offset. By separating the waveforms,
you can avoid overlapping data in the database caused by multiple
waveforms. Even if the display is set to show only the most recent
acquisition, the database keeps track of all pixel hits while the database is
building.
Remember that color grade persistence, mask testing, and histograms all
use the same database. Suppose that the database is building because
color grade persistence is ON; when mask testing or histograms are turned
on, they can use the information already established in the database as
though they had been turned on the entire time.
To avoid erroneous data, clear the display after you change oscilloscope
setup conditions or DUT conditions and acquire new data before
extracting measurement results.