SDI Eye and Jitter Measurements
How-to Guide
15
www.tektronix.com/wfm2300
15
The jitter display can be used to evaluate the
types of jitter present in the signal. Relatively
low random jitter will produce a flat line within
the jitter display as shown in Figure 12a.
Vertical deviation of the jitter display shows
the amount of jitter present within the signal.
In Figure 12b a simple 60Hz sinusoidal jitter
has been added to the SDI signal and
produces a sine wave pattern within the jitter
display with an amplitude that represents the
amount of jitter present within the signal in
this case 0.37UI or 0.25ns.
Figure 12a and 12c jitter displays are from
the same signal with different filter selections
applied for the Jitter1 HP Filter. In Figure 12a
the Timing (10Hz) filter is used and shows a
value of 0.09UI. When the filter is changed to
100kHz (Alignment Jitter) the value is
reduced to 0.05UI.
In an active device typically more than one
frequency of jitter is present within the signal
and is a complex addition of various
frequency components typically at line and
field frequencies. The
Jitter1 HP Filter
can
be selected within the WFM2300 and various
filters can be selected between 10Hz and
100kHz. While changing the filter bandwidth
note the jitter value at each selection.
Typically most jitter will be present at line
and field rate so as the value of the filter is
increased to 10kHz or 100kHz the jitter value
should decrease.
1. Select one of the tiles (1, 2, 3 or 4) and
press the
PHY
button.
2. Push and Hold the
PHY
button to
enable the menu.
3. Using the up and down arrows to
navigate to
Jitter1 HP Filter
and press
right arrow to select the sub menu as
shown in Figure 12a.
4. Press
SEL
to enter the sub menu and
choose the jitter highpass filter (Timing,
Alignment, 10Hz, 100Hz, 1kHz, 10kHz,
100kHz).
Figure 12a.
Two Field Jitter display.
Figure 12b.
Sinusoidal 60Hz jitter.
Figure 12c.
Jitter HP Filter selection of 100kHz.
