SDI Eye and Jitter Measurements How-to Guide
3www.tektronix.com/wfm2300
Serial Digital Interface (SDI) Physical Layer Monitoring
Reliable transmission of the SDI signal from point A to point B is dependent on a variety of factors such as:
Amplitude of the Signal
Overshoot
Undershoot
Jitter
Rise and Fall Time of the Transitions
These parameters are affected by the cable length, that over longer runs of cable will introduce amplitude
and frequency losses to the signal resulting in longer rise and fall times of the signal. Overshoot and
undershoot are typically a result of incorrectly terminated devices or panels which introduce reflections into
the signal. Additionally deformation of the cable can also introduce reflections into the signal along with cable
loss. Active devices may introduce jitter into the signal as the signal is processed or genlocked to a
reference signal. The first stage of troubleshooting a physical layer issue is to verify the link by using CRC
(Cyclic Redundancy Code) words to verify the link is error free. The Video Session display will shows
statistics of the CRC Errors.
Troubleshooting the SDI Signal Path
Error Free signal path, check for CRC (HD or 3G) or EDH (Error Detection Handling) if present
within SD-SDI signals. Use the video session of the WFM2300 to determine this.
Determine if the signal path has a safety margin by adding an additional length of cable or using
a stressing signal. Does the addition of the cable length or stress cause CRC issues or loss of
the signal? The cable simulator of the WFM2300 adds 20m of Belden 1694A cable along with
the ability to add an interfering signal or use the internal test signal generator with the
pathological test signal to stress the signal path.
Estimate the cable length of the signal path to determine if the receiving device is operating
within its specification, using the SDI Status displays of the WFM2300.
Check at various points along the transmission path to characterize the SDI signal.
Use the Eye displays of the WFM2300 to characterize the health and possible artifacts present
within the SDI signal along the signal path.
Use the Jitter thermometer within the eye, jitter and SDI status display of the WFM2300 to
determine the timing and alignment jitter present within the signal.
Use the Jitter display in two-field sweep to characterize the jitter within the signal and use the
high pass filters to determine the amount of jitter present within each frequency band.
