42
Figure 5-5 Oscilloscope Trigger Mode Setting
If a signal feature is not understood, the oscilloscope should be set as “
Auto
” mode, which can ensure that the
oscilloscope can also display the waveform when other trigger settings are not correct. Although the waveform
is not necessarily stable, it can provide the intuitive judgment for our further adjustment of the oscilloscope. The
signal in Figure 5-5 is the result of forced trigger in “
Auto
” mode.
When we set a specific trigger condition for a specific signal, especially when the time interval for satisfying the
trigger condition is long, we need to set the trigger mode to “
Normal
” so as to prevent the oscilloscope from
automatic forced trigger.
Figure 5-6 shows a conceptual demonstration of the acquisition memory. In order to understand the trigger event,
the acquisition memory can be divided into pre-trigger and post-trigger buffers. The position of the trigger event
in the acquisition memory is defined by the time reference point and trigger position (horizontal delay) settings.
Figure 5-6 Conceptual Demonstration of Acquisition Memory
All events displayed to the left of the trigger point
occur before trigger. These events are called pre-trigger
messages that show events before the trigger point. All events to the right of the trigger point is called post-trigger
messages. The number of delay ranges available (pre-trigger and post-trigger messages) depends on the selected
time base and memory depth.
Trigger Event
Acquisition Memory
Pre-trigger Buffer
Post-trigger Buffer
