User guide

Timing Unit Definitions
The timing unit specifies the timebase for the measurements. It is possible to
switch between the unit interval (UI) or seconds for the time scale. The timebase
is set on the View page of the Properties dialog box.
The following figure and table shows the relationship between UI and seconds for
a 500MHz signal:
An example of the measured range of time expressed in the different units is listed
below:
Table 22
Timebase Earliest
Sampling
Optimum
Sampling
Point
Latest
Sampling
Time rel. -1.5 ns 0 ns +1.5 ns
abs. 54.2 ns 55.7 ns 57.2 ns
Unit interval rel. -0.75 UI 0 UI +0.75 UI
abs. 27.1 UI 27.85 UI 28.6 UI
The Unit Interval
Unit interval values are a convenient way to express time values in a dimensionless
form. One unit interval is the equivalent of one clock period. To convert a time value
to a unit interval value, divide it by the pulse period or multiply it by the clock
frequency.
Advanced Analysis 6
Agilent J-BERT N4903B High-Performance Serial BERT 235