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Using Masks, Histograms, and Waveform Databases
CSA8000B & TDS8000B User Manual
3-159
Using Waveform Databases
A waveform database is a three-dimensional accumulation of a source waveform
as it is repeatedly acquired. In addition to the standard vertical and horizontal
dimensions, each waveform sample in a waveform database has a third dimen-
sion of count. The count reflects the number of times a specific waveform point
has been acquired or generated.
Use waveform databases for measurements, histogram calculations, mask
testing, and generating a density-style graded display. Waveform databases may
be automatically allocated for measurements, histograms, and mask testing.
Some waveform database features of note follow:
H Waveform record length is not limited to 500 (horizontal waveform database
dimension and number of horizontal display columns) when waveform
databases are active. Record lengths can vary over the entire allowable range.
H To emphasize the data that occurs less frequently, you can toggle the Invert
Color/Intensity control in the Waveform Database setup dialog box, which
reverses the intensity/color assignments to each pixel in the database display.
H You can set any selected database to use a persistence mode to accumulate
and display data. Infinite persistence mode continues displaying w aveforms
as they accumulate until the selected database is cleared manually or by a
control change. Variable persistence mode keeps and displays accumulated
data in the specified database until the user-specified waveform count is
surpassed. Each waveform accumulated beyond the count removes the oldest
waveform accumulated earlier in the database.
The following operations are excluded:
References as sources. Because references contain static data that does not
update, they are not available as a waveform source for waveform databases.
More than four waveform databases. More than four waveform databases cannot
be created at one time. Note the following behaviors regarding waveform
databases:
H There are four waveform databases; you can explicitly assign and reassign
Database1 through Database4 to waveform sources in the Wfm Database
dialog box.
H Once all databases are allocated, the only way to assign a new waveform is
to change the waveform source of one of the databases in the same dialog
box, which releases its existing source.
Why Use?
What’s Special?
What’s Excluded?