The easiest way to measure the timing difference between two signals is to measure the delay of each signal with respect to a common analog reference black or tri-level sync. To measure the delay in one of the SDI signals, connect the analog black reference signal to the external sync loopthrough on the back of the WFM700 and terminate the other side of that loopthrough. Now connect the delayed (or advanced) signal to input A or B on the back of the instrument. With the WFM700 in waveform mode, set the reference to “Internal” to lock the waveform to the SDI stream you’re measuring. Now use the cursor controls to position the left cursor on a memorable portion of the waveform (a color bar transition or the fake black burst etc...). Now set the reference to “External” and if the signal is in fact delayed, you should see the waveform shift to the left or right. Now use the cursor controls and position the right cursor to the same memorable point from earlier. The cursor delta should now read the timing delay (or advance) of your signal under test. Repeat the above steps for the second signal in your system and then compare the two delay measurements to determine the overall delay between your two SDI signals.