| Electronics > Beginners |
| oscilloscope auto trigger explained |
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| stern0m1:
Hi, Im using the RIGOL DS1054Z. I want the oscilloscope just to continuously display the voltage levels it reads. Is auto trigger going to give me this? Below is how the manual explains it. I dont understand it. Is there no mode where it would just continuously read the voltage levels? Im a beginner, obviously. :) The manual states: Auto: No matter whether the trigger condition is met, there is always waveform display. A horizontal line is displayed when no signal is input. In this mode, the oscilloscope operates by first filling the pre-trigger buffer. It starts searching for a trigger after the pre-trigger buffer is filled and continues to flow data Pre-trigger Buffer Post-trigger Buffer through this buffer while it searches for the trigger. While searching for the trigger, the oscilloscope overflows the pre-trigger buffer and the first data put into the buffer is first pushed out (First Input First Out, FIFO). When a trigger is found, the pre-trigger buffer would contain the data acquired just before the trigger. If no trigger is found, the oscilloscope will trigger forcefully. If forceful trigger is invalid, the oscilloscope still displays waveform but the waveform is not stable; if forceful trigger is valid, the oscilloscope displays stable waveform. |
| Brumby:
--- Quote from: stern0m1 on October 07, 2018, 01:13:39 am ---The manual states: Auto: No matter whether the trigger condition is met, there is always waveform display. A horizontal line is displayed when no signal is input. --- End quote --- This is the bit you need to understand - and it's pretty straightforward. For a DC input, there will be a line displayed - and it will be shifted from zero exactly as you would expect. The rest of the text you quoted is an explanation of the process that happens within the scope - which isn't really of interest for a simple voltage measurement. |
| PTR_1275:
Putting the scope in roll mode might help as well, depending on what you are wanting and hoping to see |
| bitseeker:
stern0m1, yes, auto trigger will make the scope draw a trace regardless of the trigger level that's set. As Brumby said, for a steady DC voltage you'll see a straight line. For a voltage that changes over time, you'll see that as well, but depending on how fast it changes, your time base setting, and your trigger level, it may be difficult to see clearly. If you want to see a slowly changing voltage drawn across the screen like a graph, that's what roll mode is for. It'll make the screen like a roll of paper with the trace being drawn across it continuously. Roll mode on the DS1054Z is enabled automatically when the horizontal time base is set to 200 ms or longer. So, give these a try to see what works best for the signal you're wanting to look at. |
| vk6zgo:
It was a common technique with analog 'scopes to put them into auto trigger,so that they would "free run", tracing a line across the screen. In DC coupled mode, this was very useful for quick checking of DC supplies, or for adjusting DC voltages for a maximum ot minimum value. It sounds like this is what you want to do. Early DSOs that I used did not have an equivalent "free run" function, so we had to try to use the "roll" mode, which was pretty useless, as it wanted to display the DC variation as a slow waveform, making it very difficult to see variations in level to adjust things. Modern DSOs do have such a mode, so can probably be used in the same way as an analog instrument (I do not have any type of DSO, either old or new, so the comment about modern ones is based on what I have read in this forum & others). |
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