UTD2000 Series User Manual 
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Scan Mode:When the horizontal time base control is set at 100ms/div or slower, the 
instrument enters the slow scan sampling mode. When using the slow scan mode to 
observe low frequency signals, it is recommended to set the channel Coupling to DC. 
SEV/DIV:Horizontal scale (time base) units, such as waveform sampling is stopped 
(using the RUN/STOP button), and the time base control expands or compresses the 
waveform. 
 
3.3 Window extension 
Window extension time base function is used to observe the waveform detail for a 
given window of the waveform. User can active this function by pressing F3 button at the 
horizontal function menu. 
 
 
 
 
 
 
 
 
 
 
 
Figure 3-2 Screen Display under Window Extension 
Under Window extension time base, there are two display areas, as shown in the 
figure above.  The original waveform is displayed in the upper part, this area can be 
moved left and right by turning horizontal POSITION
 knob or can be enlarged and 
reduced by turning the horizontal SEC/DIV
 knob.   
The waveform generated through horizontal extension time base of the selected 
original waveform area shall be displayed in the lower part.    As the waveform displayed 
in the whole lower part corresponds to the selected area in the upper part, the extension 
time base can be enhanced by turning horizontal SEC/DIV
 knob to reduce the selected 
area of the waveform. 
 
3.4 Trigger hold-off time adjustment   
Trigger hold-off time is the time interval between two trigger events (100ns by default); 
Trigger hold-off time can be adjusted by using the multi-purpose knob at the horizontal 
function menu. 
During trigger hold-off, DSO will not be triggered any new event until the hold-off time 
is over. For example, if a set of pulse train shall be triggered from the first pulse upon 
request, then the hold-off time can be set as the pulse train width. As shown as below.   
Waveform horizontal extension part 
Waveform horizontal extension part 
Extension time base