174 Keysight InfiniiVision 3000T X-Series Oscilloscopes User's Guide
11 Triggers
 
Edge then Edge Trigger
The Edge then Edge trigger mode triggers when the Nth edge occurs after an 
arming edge and a delay period.
The arm and trigger edges can be specified as   (Rising) or   (Falling) edges on 
analog or digital channels.
1 Press the [Trigger] key.
2 In the Trigger Menu, press the Trigger softkey; then, turn the Entry knob to 
select Edge then Edge.
3 Press the Sources softkey.
4 In the Edge then edge Sources Menu: