OWON SDS Series - Manual (Page 46)

5.Advanced User Guidebook
selected as a trigger source whatever displayed or not.
 Ext Trig: The instrument can be triggered from a third source while acquiring data
from CH1 and CH2. For example, to trigger from an external clock or with a signal
from another part of the test circuit. The EXT, EXT/5 trigger sources use the
external trigger signal connected to the EXT TRIG connector. Ext uses the signal
directly; it has a trigger level range of -0.6V to +0.6V. The EXT/5 trigger source
attenuates the signal by 5X, which extends the trigger level range to -3V to +3V.
This allows 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 power cord, so you do not have to input an AC trigger signal.
When AC Line is selected as trigger source, the oscilloscope automatically set
coupling to DC, set trigger level to 0V.
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.
 Normal: The Normal mode allows the oscilloscope to acquire a waveform only
when it is triggered. If no trigger occurs, the oscilloscope keeps waiting, and the
previous waveform, if any, will remain on the display. Single: In Single mode,
after pressing the Run/Stop key, the oscilloscope waits for trigger. While the
trigger occurs, the oscilloscope acquires one waveform then stop.
 Single: In Single mode, after pressing the Run/Stop key, the oscilloscope waits for
trigger. While the trigger occurs, the oscilloscope acquires one waveform then
stop.
3. Coupling:
Trigger coupling determines what part of the signal passes to the trigger circuit.
Coupling types include AC, DC, LF Reject and HF Reject.
 AC: AC coupling blocks DC components.
 DC: DC coupling passes both AC and DC components.
 LF Reject: LF Reject coupling blocks DC component, and attenuates all signal
with a frequency lower than 8 kHz.
 HF Reject: HF Reject coupling attenuates all signals with a frequency higher
than 150 kHz.
4. Holdoff: Trigger holdoff can be used to stabilize a waveform. The holdoff time is
the oscilloscope's waiting period before starting a new trigger. The oscilloscope will
not trigger until the holdoff time has expired. It provides a chance for user to check
the signal in a short period and helps to check some complex signals, such as AM
waveform etc.
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