Trigger Source; Trigger Mode - Rigol DS1074B User Manual

Trigger Terms Explanation

1. Trigger Source:

Trigger occurs from several sources: Input channels (CH1, CH2, CH3, CH4), AC
Line, Ext, Ext/5.
CH1, CH2, CH3, CH4:

It is the most commonly used trigger source. The channel works when it is
selected as a trigger source whatever displayed.
 Ext Trig:
The instrument can be triggered from an external source while acquiring data
from CH1, CH2, CH3, and CH4. For example, be a trigger source with an
external clock or a signal from another part of the test circuit. The Ext, Ext/5
trigger sources use an external trigger signal connected to the EXT TRIG
connector. Ext uses the signal directly; it has a trigger level range of -0.6 V to
+0.6 V. The EXT/5 trigger source attenuates the signal by 5X, which extends the
trigger level range to -3V to +3 V allowing the oscilloscope to trigger on a larger
signal.
AC Line:

AC power can be used to display signals related to the power line frequency,
such as lighting equipment and power supply devices. The oscilloscope gets
triggered on its AC power input, but an AC trigger signal is not required.

2. Trigger Mode:

The trigger mode determines how the oscilloscope behaves in the absence of a
trigger event. The oscilloscope provides three trigger modes: Auto, Normal, and
Single.
Auto:

This sweep mode allows the oscilloscope to acquire waveforms even when it
does not detect a trigger condition. If no trigger condition occurs while the
oscilloscope is waiting for a specific period (as determined by the time-base
setting), it will force itself to trigger.
When forcing invalid triggers, the oscilloscope cannot synchronize the waveform,
and the waveform seems to roll across the display. If valid triggers occur, the
User's Guide for DS1000B Series
RIGOL
2-47