2-21
IM 704510-01E
Explanation of Functions
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2.7
Statistical Calculation and Inter-Symbol
Interference Analysis
Statistical Calculation (see section 9.1 for the operating procedure)
The statistical calculation values can be displayed in a list format on the statistics display as
well as on the time variation display and histogram display.
This section describes the area for performing the statistical calculation, constant T, and the
statistical calculation parameter settings used to determine the statistical calculation values.
Setting the Area for Performing Statistical Calculation
You can select whether to calculate the statistics using the measured values in the
window area or the area enclosed by markers. The window area is determined by the
scale value of the measured value axis on the histogram display; it is determined by the
scale value of the time stamp axis on the time variation display.
If the time variation is displayed on data that was block sampled in the time stamp mode,
you can also select the [Block] on which to calculate the statistics.
If you are using the multi window or auto window function, the statistics are calculated
over the area enclosed by markers for each window.
• When calculating the statistics over an area enclosed by markers
• For histogram display
X1 marker
X2 marker
Y marker
• For time variation display
Y1 marker
Y2 marker
Calculated using the data in this area
X1 marker
X2 marker
Setting the Slope (Calculation Slope)/Polarity (Calculation Polarity)
You can specify the slope and polarity for the statistical calculation only for the following
measurement functions.
The statistics can be calculated separately on data having the specified slope or polarity.
• A-to-B time interval measurements, when the slope setting is either
A B
or
A B
.
• Pulse width measurements, when the polarity setting is
.
• Pulse width A & A-to-B time interval measurement.
• Pulse width A & pulse width B measurement.
Setting Constant T
The T value used when calculating the jitter (statistical value) or “Deviation/T” (statistical
calculation parameter) (see the next page) is set as constant T. When the item being
measured is an optical disk, this value corresponds to the period of the read clock signal.
You cannot change the value of T when using the auto window function since it is
automatically set.
Differences in the Statistical Calculation due to the Differences in the Sampling
Mode and Display Format
There are some statistical values that differ in their equation depending on the sampling
mode (see “Statistical Calculation Parameters” on the following pages). In addition,
statistics can be calculated based on the measured values (during time stamp mode) or
histogram (during hardware histogram mode).
In the time stamp mode, you can select to calculate the statistics on the time variation or
on the histogram. The following differences exist between the time variation display and
the histogram display.
Time variation: You can set the area over which to calculate the statistics with the time
stamp and measured value.
Histogram:
You can set the area over which to calculate the statistics with the
measured value (median value) and the frequency of occurrence.