What is the trigger mode of an oscilloscope?
Oscilloscope "trigger" is to make the oscilloscope scanning and the observed signal synchronous, so as to display a stable waveform. In order to meet different observation needs, different "trigger modes" are required. There are three basic trigger modes for oscilloscopes:
The first is the "automatic mode (AUTO)", in this mode, when the trigger does not occur, the oscilloscope's scanning system will automatically scan according to the set scanning rate; and when the trigger occurs, the scanning system will try to scan according to the frequency of the signal, so in this mode, regardless of whether the trigger conditions are met, the oscilloscope will generate a scan. Therefore, in this mode, no matter whether the trigger conditions are met or not, the oscilloscope will generate a scan, and you can see the scanning line on the screen with changes, which is the characteristic of this mode.
The second is "Normal Mode/Regular Mode (NORM)", this mode is different from the automatic mode, in this mode the oscilloscope will scan only when the trigger conditions are met, and if there is no trigger, no scanning will be performed. Therefore, if there is no trigger in this mode, for analogue oscilloscopes will not see the scan line, there is nothing on the screen, for digital oscilloscopes will not see the waveform update, do not understand this will often think that the signal is not connected or any other fault.
The third is the "single mode (SINGLE)", this mode and the "normal mode" is somewhat similar, that is, only when the trigger conditions are met to produce a scan, otherwise no scanning. The difference is that this scanning, but produced and completed, the oscilloscope scanning system is to enter a resting state, even if the back again to meet the trigger conditions of the signal is no longer scanning, that is, triggering a single scanning once, that is, a single time, you must manually restart the scanning system in order to produce the next trigger. Obviously, for ordinary analogue oscilloscopes in this mode you will often find that nothing can be seen, because the waveform flashes, the oscilloscope can not be retained, on most occasions this mode is not useful. The above three trigger modes are provided by most oscilloscopes.
