UTD2000 Series User Manual 
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4.6 Trigger Holdoff 
Trigger holdoff time adjustment is used to observe complex waveform (pulse string series). 
Holdoff time refers to the waiting time for the DSO to restart trigger circuit. During holdoff 
time, the DSO will not trigger until the holdoff time is over. 
Table 4-9 Trigger Holdoff Menu 
Press to turn on the main time base.   
Main time 
base/extensive 
time base 
Main time base: set  as main time base, the main time base will 
change when adjusting horizontal time base. 
Extension time base: set as extension time base, the extension time 
base will change when adjusting horizontal time base. 
Press to turn on the extension time base. 
To adjust the trigger hold-off time by multi-purpose knob. 
 
Take pulse series as example, trigger the first pulse on the pulse series, then the holdoff 
time can be set as pulse string width. As shown in the figure below: 
 
Figure 4-4 Snychronous complex waveform 
 
Operation Instruction: 
(1) Based on the synchronization mode of normal signal, select to trigger edge, trigger 
source, slope of  TRIG MENU and adjust trigger level to make the waveform stable as 
possible. 
(2) Press HORI MENU to display horizontal menu. 
(3)  By  adjusting  the  multifunctional  knob,  the  holdoff  time  will  be  changing  until  the 
waveform is stable. 
 
4.7 Explanation of nouns 
(1) Trigger source: Trigger can be achieved from several signal sources: input channels 
(CH1 and CH2), external triggers (EXT) and AC line.   
■ Input channel: The most frequently-used trigger source is input channel (selectable). 
The  selected  channel  as  trigger  source  can  operate  normally  no  matter  its  input  is 
displayed or not.