User Manual

Sampling oscill

oscope concepts

Auto mode, when forcing triggers in the absence of valid triggering events, does not synchronize the w aveform on the

display. The wa

veform will appear to roll across the screen. If valid triggers occur, the display will become stable.

Normal trigger mode. Normal mode sets the oscilloscope to acquire a waveform only when a trigger condition occurs.

If no trigger occurs, the last waveform record acquired remains on the display. If no last waveform exists, no waveform

is displayed.

Holdoff trigger mode. The Holdoff trigger mode lets you set a time period during which the oscilloscope ignores trigger

events. For e

xample, to trigger on the ﬁrst pulse of a pulse burst, you would set the trigger conditions to trigger on a positive

edge, and set the holdoff value so that the trigger is disabled for a period of time after the trigger event but before the next

bust occurs. Using Holdoff in this case prevents the oscilloscope from triggering on any positive s ignal edge.

Use Set Holdoff to minimum to set the holdoff value to the minimum value.

NOTE. The trigger mode does not set the trigger conditions; those are set with the trigger Type controls. (See page 27,

Available trigger types.)

Trigger delay (acquisition mod e)

In nor

mal acquisition modes, the trigger point is located at the center of the waveform record, and is positioned at the

center-screen expansion point so that horizontal scale changes are centered around the trigger point. The Delay function

in the Acquire menu disconnects the trigger point from the center-screen expansion point. This feature lets you use the

Horiz

ontal Position knob to reposition (delay) the trigger point from the expansion point by a speciﬁed amount.

The mo

st com m o n use for Delay is to acquire and display waveform detail that is separated after the trigger event by a

signiﬁcant interval of time. For example, you can trigger on a pulse that occurs once every 10 ms and then use Delay to look

at the signal characteristics that occur 6 ms after the trigger point.

TBS2000 Series User Manual 29