> For a low duty cycle pulse, the ac coupled signal will be approximately the > same as if it were dc coupled. Not sure I follow what you mean. There will > be only one rising edge for a narrow pulse ac coupled, as the falling edge > occurs much quicker than the HPF time constant. If there is overshoot, it will be undershoot on the falling edge. You can trigger on the undershoot if you are triggering on rising edge and the trigger level is slightly below ground. -- These are my opinions. I hate spam.