Hi hhonza,
Try disabling the video trigger when you are playing back the capture. This will allow you to scroll through the data. When you are playing the signal back and the video trigger is active, it attempts to find triggers in the capture and overrides your manual scrolling.
Once you are able to scroll through the data, try zooming in on the falling edge of that pulse to verify it is a smooth descent.
The trigger position control only affects the display of the IQ data. The pre-trigger setting on the IQ recording toolbar affects how much data before the trigger gets saved.
Let me know if you have additional questions.
Regards,
Andrew
