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Term interpretation
1. Source:
Trigger can occur from several sources: Input channels (CH1, CH2), AC Line, Ext, Ext/5.
* Input:
It is the most commonly used trigger source. The channel will work when selected as a
trigger source whatever displayed or not.
* Ext Trig: The instrument can trigger from a third source while acquiring data from CH1 and CH2. For
example, you might want 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 +1.6 V to
-1.6 V. The EXT/ 5 trigger source attenuates the signal by 5X, which extends the trigger level
range to +8 V to -8 V. 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. Hold off:
A time interval before the oscilloscope responses to next trigger signal. During this Hold off period, the
trigger system becomes "blind" to trigger signals. This function helps to view complex signals such as an
AM waveform. Press Hold off button to activate "TRIG LEVEL" knob, then turn it to adjust Hold off time.
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