How to ? Set up triggering from the Trigger Setup Window
3. Click a Trigger Type button to select a trigger, such as Edge, that u ses a level adjustment. A trigger
uses a level adjustment if the Level control appears within the trigger graphic
(see page 386),along
with the other
trigger type setup controls.
4. Click Level, and then click the keypad icon to open the keypad. Click on either TTL, ECL, or USER:
TTL. Sets the trigger level to +1.4 V.
ECL. Sets the trigger level to –1.3 V.
USER. You can set the trigger level to a preset voltage.
When you set the volts/div less than 200 m V, the instrument reduces the TTL or ECL trigger levels
below standard TTL and ECL levels. This reduction occurs because the trigger level range is fixed at
+12 divisions from the center. At 100 mV (the next lower setting after 200 mV) the trigger range is +1.2 V,
whichislessthanthetypicalTTL(+1.4V)orECL(–1.3V)level.
Define pr
eset levels
1. From the Utilities menu, select user Preferences.
2. In the User Preferences control window, open the Keypad Defaults tab.
3. Click in the appropriate Trig Level entry box; then use the pop-up keypad or multipurpose knob to
adjust the preset.
4. If desired, click a Keypad Label and change the label of the preset using the pop-up keypad.
Force a trigger
When using Normal trigger mode, forcing a trigger is useful if the input signal is not supplying a valid
trigger.
1. Push the front-panel Advanced button.
2. In the Trigger control window, open the A Event or B Event tab
3. In the Trigger Type drop-down list, select Edge.
4. To force the instrument to immediately acquire one waveform record, even without a trigger event,
click the Force Trigger button.
TIP. Click Force Trigger to quickly confirm there is a signal present for the instrument to acquire. Then
determine how to trigger on the signal. For example, push LEVEL to set 50%, check the trigger source
setting, and so on.
NOTE. The instrument acts on a Force Trigger even if it is selected before the end of pretrigger holdoff.
However, the button has no effect if the acquisition system is stopped.
640 DSA/DPO70000D, MSO/DPO/DSA70000C, DPO7000C, and MSO/DPO5000 Series
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