HP 54710A, User'S Reference Manual

Page: 212 / 412

To view the variable part of the jitter, you must have a synthesized,
crystal-controlled signal source because the source must have less jitter than
the oscilloscope’s time base. You can use these HP signal sources to
characterize time base jitter:
•
HP 8656B (see following paragraph)
•
HP 8657A (see following paragraph)
•
HP 3335A synthesized function generator
•
HP 80000 pulse/pattern generator
The faster the slew rate of the source, the easier it is to evaluate jitter. One
way to get fast-slewing edges is to trigger a pulse generator, such as an
HP 8130A or HP 8131A, with a stable sine-wave source, like an HP 8656B or
HP 8657A.
To see the variable jitter, set the Position in the Time Base menu to a large
number relative to the Scale setting. As you increase the value of Position,
you will see the jitter increase. The HP 54720’s variable jitter is on the order
of 10 to 20 ppm, so you must use a large value of Position and a fast setting of
Time Base Scale to see it. You can use the automatic measurements in the
oscilloscope to measure the jitter and observe its statistics. To calculate the
slope of the variable jitter, subtract the fixed jitter from the observed jitter
and divide by the Position setting.
The jitter in the oscilloscope has approximately normal distribution. For
measuring jitter that also has a normal distribution, the standard deviations
add in quadrature (equation 1).
Equation 1
(
Measured jitter
) 2 =
(
Signal
jitter
)
2 +
(
Scope
jitter
)
2
Measurements
Statistics
13–27