Pulse Triggering
TDS 620A, 640A, & 644A User Manual
Regardless of the polarity setting, triggering occurs at the point the runt
pulse
recrosses
its first threshold.
When you select the pulse class Width, the oscilloscope will trigger on a
pulse narrower (or wider) than some specified
range
of time (defined by the
upper limit and lower limit).
Polarity
To define whether the pulses are positive or negative:
Press TRIGGER MENU ➞ Type (main) ➞ Pulse (pop-up) ➞ Class (main) ➞
Width (pop-up) ➞ Polarity (main) ➞ Positive or Negative (side).
Trig When
This menu item lets you establish the range of widths (in units of time) the
trigger source will search for and whether to trigger on pulses that are outside
this range or ones that fall within the range.
1. Press TRIGGER MENU ➞ Type (main) ➞ Pulse (pop-up) ➞
Class (main) ➞ Width (pop-up) ➞ Trig When (main).
2. Press Within Limits (side) if you want the oscilloscope to trigger on
pulses that fall within the specified range. If you want it to trigger on
pulses that are outside the range, then press Out of Limits (side).
3. To set the range of pulse widths in units of time, press Upper Limit (side)
and Lower Limit (side). Enter the values with the general purpose knob
or keypad. The Upper Limit is the maximum valid pulse width the trigger
source will look for. The Lower Limit is the minimum valid pulse width.
The oscilloscope will always force the Lower Limit to be less than or
equal to the Upper Limit.
Level
To set the trigger level with the Level main menu:
Press TRIGGER MENU ➞ Type (main) ➞ Pulse (pop-up) ➞ Class (main) ➞
Width (pop-up) ➞ Level (main) ➞ Level, Set to TTL, Set to ECL, or Set to
50% (side).
See
Triggering
, on page 2-13.
See
Triggering
, on page 3-142.
Width Operation
For More
Information