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Show us your square wave
Fungus:
--- Quote from: Mechatrommer on August 31, 2020, 06:08:13 pm ---
--- Quote from: Electro Fan on August 31, 2020, 05:22:03 pm ---That looks like a very fast Rigol 1054Z
--- End quote ---
thats look like it but i dont know, thats what it said... i'm also a bit surprised...
--- End quote ---
Plenty of people have seen similar results with the right cables, termination, etc.
(it's buried somewhere in the massive Rigol thread....)
Electro Fan:
After looking at your Rigol posts and my Rigol while playing with the cursors, I think there is an error in the way we are I am using/interpreting the cursor measurements.
I think your AX numbers of -800 and -500 ps are the distance to the left of the trigger line, and your BX numbers of 700 ps and 1.3 ns are the distances to the right of the trigger line.
Try using the built-in Rigol Rise Time measurement and see if you get a number that is different than what your AX and BX cursor measurements are displaying.
The BX-AX is more likely the Rise Time.
I got mesmerized by looking at ps measurements; I'm guessing what the Rigol cursor measurements are trying to tell us is that the Rise Time is 1.5 ns to 1.8 ns which would imply about 233 MHz to 190 MHz - still very fast for a 1054Z but somewhat more plausible.
Try the Rigol built-in Rise Time measurement and let us know. My bad for even raising the issue. Sorry. :palm:
Electro Fan:
Attached is a file showing the 2072 Rise Time of 3.3 ns.
Note that the B->X = 2.000ns display just happens to be highlighted because the cursor menu selection was set to SelectCursor X and CursorB. So your eye is drawn to what is highlighted; makes sense except that if what you are really looking for is DeltaX (what I think is the Rise Time), then you might be (in my case, at least) temporarily confused. :palm:
On the 2072 Rigol uses the convention DeltaX and on the 1054Z Rigol uses the BX-AX convention. These are nitty little things but either way until you are fully indoctrinated (or at least paying attention, duh), it's possible to misinterpret a displayed value. All good lessons that I'm happy to have learned. |O :-DD
And, I'm still leaving open the possibility that I'm still missing something..... so feel free to point it out.... I heard someone say recently we learn much more from our mistakes than when we get it right. I'm feeling like I'm continuously in the deep end of the learning pool. :)
Slightly veering off topic but I just noticed... doesn't seem like the Rigol 2072 display shows the 10% and 90% markers that would be nice to have for RT measurements.
T3sl4co1l:
Not having seen the settings, acquisition and all that -- it could easily just be a glitch, with sinc interpolation making it look believable. (The suspiciously small number of points seems to hint at that?)
I can do the same thing, to literally unbelievable risetimes, on my TDS460 -- this being relatively easy as it uses equivalent time sampling. (Heh, though I don't know how I'd trick it to acquire a nice step; it's random sampling I believe, it just assembles a waveform bit by bit.)
Heh, and at maximum settings (1ns/div sweep, 50x zoom), it can show all the way down to 20ps/div. Not that anything it can properly acquire is at all meaningful there (it's only 350MHz BW).
Tim
graybeard:
This is the output of my 1GHz Colby PG100A pulse generator running at 200 MHz into my 1GHz Tektronix TDS784D. The Colby (with GaAs drive option) is rated for a rise and fall time of <250ps, so the times shown are a limitation of the scope.
Click on the images above for a larger version.
Chris
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