There are several common trigger modes for oscilloscopes
For digital oscilloscopes, the whole machine works under the control of the trigger circuit. The trigger circuit determines when the oscilloscope acquires signals and when it stops to display waveforms. The trigger mode is the working state of the oscilloscope before and after the trigger conditions are met. The following trigger modes are commonly used in oscilloscopes:
AutoTrigger Mode: This is the default trigger mode of most oscilloscopes. In AutoTrigger Mode, the oscilloscope will give priority to detect whether the set trigger conditions are satisfied. If the trigger conditions are met, the oscilloscope will be triggered according to the current trigger conditions; if the trigger conditions are not met and last for more than a certain period of time (usually tens of ms), the oscilloscope will automatically generate a trigger and capture the waveform display. If the oscilloscope is auto-triggered, the captured waveform may not meet the trigger conditions, but this avoids the situation where the user cannot see the signal waveform at all due to the wrong trigger condition settings, and the user can further change or optimise the trigger condition settings according to the waveform captured by the oscilloscope auto-trigger. Auto-trigger mode can be applied to most of the test occasions, but there are certain constraints. If the signal that the user is interested in jumps or the trigger conditions are set to occur very infrequently, for example, only once a second, then if the oscilloscope is working in auto-trigger mode, it may be too late to wait for a signal that meets the trigger conditions before the oscilloscope is automatically triggered, resulting in the capture of the signal is not the desired signal situation. In automatic trigger mode, whether to meet the conditions of the trigger or the oscilloscope automatically generated trigger, once triggered the oscilloscope will be captured waveform processing display, and then wait for the arrival of the next trigger, so regardless of whether the trigger conditions to meet the oscilloscope on the waveform are "moving" up.
Normal Trigger (NormalTrigger Mode): If the user wants to capture a signal with a long interval, and the trigger conditions are set correctly, the oscilloscope can be set to Normal Trigger Mode. In NormalTrigger Mode, the oscilloscope will be triggered strictly according to the set trigger conditions. If the trigger conditions are not met, the oscilloscope will keep waiting for the arrival of the signal that meets the trigger conditions and will not trigger automatically. In normal trigger mode, the oscilloscope will also process and display the captured waveform once it is triggered, and then wait for the arrival of the next trigger. Therefore, if the waveforms with trigger conditions continue to arrive, the waveforms on the oscilloscope are "moving"; if the waveforms that satisfy the trigger signals never arrive, the waveforms on the oscilloscope are not moving and are not updated, so the waveforms on the oscilloscope are not updated.
SingleTrigger Mode: Under normal triggering conditions, when a new waveform that meets the triggering conditions arrives, the previous waveform will be updated, but sometimes it is necessary to capture some single or transient situations (such as capturing the waveform when the system is powered on, the waveform when the switch is turned on, the waveform when the clock is just starting to oscillate, etc.), and we are concerned about the waveform of the first signal that meets the triggering conditions. We are concerned about the waveform of the first signal that meets the trigger conditions, and then the oscilloscope can be set to single trigger mode. In the single trigger mode, once the trigger conditions are met, the oscilloscope will process and display the captured waveform, and will not carry out subsequent triggering and acquisition.
Digital Although digital oscilloscopes have a relatively large dead time, due to the use of digital technology, it is possible to set up a very rich set of trigger conditions. If the user can roughly estimate the characteristics of the signal that may be captured, it is possible to set up the corresponding trigger conditions according to the characteristics of the signal to be captured. It can be said that the ability to set trigger conditions to capture signals according to the signal characteristics reflects the user's proficiency in operating the oscilloscope. The following section introduces the meaning of commonly used trigger conditions in oscilloscopes and how to set trigger conditions to capture signals.
