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5.7
Trigger Coupling
Press the Setup button on the front panel to enter the TRIGGER menu, then press the Coupling
softkey and turn the Universal Knob or press the Coupling softkey continually to select one of
the following trigger coupling modes:
•
DC: Allows both DC and AC components into the trigger path.
•
AC: Blocks the DC components and attenuates signals lower than 8 Hz. Use AC coupling
to get a stable edge trigger when your waveform has a DC offset.
•
LF Reject: Blocks the DC components and rejects the low frequency components below
900 kHz. Use LF Reject coupling to get a stable edge trigger when your waveform has low
frequency noise, power line harmonics, etc.
•
HF Reject: Reject high frequency components higher 500 kHz.
5.8
Trigger Hold Off
Trigger Hold Off can be used to stabilize the triggering of complex waveforms such as series of
pulses. Hold off time is the amount of time that the oscilloscope waits after a trigger event
before re-arming the trigger circuitry. The oscilloscope will not trigger until the hold off time
expires.
Use the Hold Off option to trigger on repetitive waveforms that have multiple edges (or other
events) between waveform repetitions. You can also use the Trigger Hold Off to trigger on the
first edge of a burst when you know the minimum time between bursts.
For example, to get a stable trigger on the repetitive pulse burst shown below, set the hold off
time to be greater than 200 ns but less than 600 ns.
Figure 45 - Trigger hold off
To set the Hold Off:
1. Press the Run/Stop button to stop waveform capture, and then use the Horizontal Position
knob and the Horizontal Scale knob to find where the waveform repeats.
2. Measure this time using cursors or using the screen's graticule.
Note: Trigger coupling is different from channel coupling.
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