thanks for the example, very useful. So the trigger would be like that input that triggers the shutter release at the right time. If the trigger triggers right, we will have the signal on the display, otherwise not.
Exactly. You might end up with a spaguetti of overlapping signals if you make a poor decision for the trigger.
For example (seeing actual operational errors helps a lot!) use the reference signal from the scope to test different trigger voltage values.
If the trigger is +- 1 V (I don't remember) and you try to trigger at 1 V it won't be able to draw the square wave accurately. You don't want it to trigger on a "flat" part of the signal of interest. Instead, try triggering on an edge, for example on 0.5 V, and you will see a clear representation.
Basically default the center of the display is the trigger point, and there the signal is born which we will then see on the display
I think I should have understood these things before, it would have been easier. Now I must also understand how long the signal trace is: only the length of the display? infinity? this is another thing that I don't have in mind, and it is not a beautiful thing ..
You can move the triggering point on the screen as well. Maybe there is a triggering event but you want to see what happened before the that event. Remember, the oscilloscope is a camera to take pictures of time, while a photo camera takes pictures of space.
To do that, use the "position" control below the horizontal knob.
And this is a really useful trick you can't do with an analog scope. You can capture a single event, freeze it on screen, and "zoom" into the horizontal range using the horizontal control.
To do that, use the "Single" triggering button.
(Unfortunately that "zooming" is not possible in the vertical axis due to limitations in the input electronics). The resolution of that "horizontal zoom" will be limited by the memory capture size you configure.