Table 3 1: A Sample Assignment Of Colors To Hit Density - Tektronix 11801C User Manual

11801C User Manual
updated with new data (this also applies to histogram displays). The range
for refresh rate is 5 s to 180 s. To change the refresh rate, display the Per
sist/Histograms pop up menu and touch Refresh Rate. Both of the knobs
are now assigned to control the refresh rate.
You can also set the refresh rate to 0 using the keypad pop up menu, which
means the display is never updated. The color graded database is not
affected by the refresh rate (only the display is), so setting the refresh rate to
0 may speed some computations, such as measurements.
If any displayed waveform has a record length longer than 512 points when
Color Grading is selected, the record length is set to 512 points and a
message is displayed informing you of the change in record length.
Interpreting the Color Graded Display
Colors in the color graded display are based on the number of hits that have
fallen in a bin", with a bin assigned to each pixel of the display. A bin can
represent a maximum of 65,535 hits. In a single graticule display, the bins
are arranged in a 512 (horizontal) by 256 (vertical) matrix. In a dual graticule
display, there are 512 (horizontal) by 128 (vertical) bins on each graticule.
There are three algorithms used to assign colors to the display. The algo
rithm used depends on the maximum number of hits for any pixel in the
display. These algorithms are detailed in Appendix D, Algorithms. An exam
ple of the assignment of colors is shown in the table below. Max in the table
represents the maximum number of hits in any bin, which for this algorithm
must be at least 16.

Table 3 1: A Sample Assignment of Colors to Hit Density

Hit Density
1/2 Max to Max
1/4 Max to 1/2 Max -1
1/8 Max to 1/4 Max -1
1/16 Max to 1/8 Max -1
1 to 1/16 Max
To see the actual range of values represented by each color, press Color
Grad Scale in the Display Modes major menu. The Color Grad Scale
pop up menu shows the hit density for each of the five waveform colors. The
hit density readouts are updated when the 11801C updates the color
graded display.
Default Color Maps To
Pale Yellow Trace Color 1
Rose Trace Color 2
Purple Trace Color 4
Light Blue Window Trace
Green Trace Color 3
Display Persistence
3 45