Color graded display, mask testing, and histograms all use the same data
base, and turning on any one of them starts building the data base. Suppose
that the data base is building because color graded display is turned on.
When mask testing or histograms are turned on, they take advantage of the
information already established in the data base as if they had been turned on
the entire time.
You may notice the following histogram statistics listed below the graticule
area. Figure 24-2 shows an example histogram.
•
Scale – Scale lists the display scale in hits per division or dB per division.
•
Offset – Offset lists the offset in hits or dB. Offset is the number of hits or
dB at the bottom of the display, as opposed to the center of the display.
•
Mean – Mean is the average value of all the points in the histogram.
•
Median – 50% of the histogram samples are above the median and 50% are
below the median.
•
Std dev – The Standard deviation (
σ
) value of the histogram.
•
Hits – The total number of samples included in the histogram.
•
P-P – The width of the histogram. For horizontal histograms, width is the
difference time between the first and last pixel columns that contains data.
For vertical histograms, width is the difference in time between the first
and last pixel rows that contain data.
•
Peak – The number of hits in the histograms’s greatest peak.
•
µ±
1
σ
– The percentage of points that are within
±
1
σ
of the mean value.
•
µ±
2
σ
– The percentage of points that are within
±
2
σ
of the mean value.
•
µ±
3
σ
– The percentage of points that are within
±
3
σ
of the mean value.
Histogram Menu
Histograms in the oscilloscope
24–4
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