5.Advanced User Guidebook
42
Term interpretation
1. Source
: Trigger can occur from several sources: Input channels (CH1, CH2), 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 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
-
0.6 V to
+
0.6 V. The EXT/5 trigger source attenuates the
signal by 5X, which extends the trigger level range to
-
3 V to
+
3 V. This allows the
oscilloscope to trigger on a larger signal.
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.
How to Operate the Function Menu
The function menu control zone includes 8 function menu buttons:
Measure, Acquire,
Utility, Cursor, Autoscale, Save, Display, Help
and 4 immediate-execution buttons:
Autoset, Run/Stop, Single, Copy.
