General > General Technical Chat
The Rigol DS1052E
Mark_O:
--- Quote from: Mark_O on March 18, 2010, 10:15:50 am ---Agilent did a paper on noise in digital scopes a while back, and it was quite illuminating. Even very expensive scopes can exhibit surprisingly high levels of relative noise, under some circumstances as much as 50% of one vertical division on a peak-to-peak basis! Turn on infinite Persistence, and things can get pretty ugly. ;)
--- End quote ---
They also did a nice job of dispelling the myth that digital scopes are intrinsically "noiser" than analog scopes. At first look, it seems obvious that the signals on a digital scope are much noiser, but that's attributable mostly to the difference in acquisition and display methods. I.e., the higher peak-to-peak noise levels you see on your digital scope are captured and displayed instantaneously. The exact same signal displayed on an analog scope will show much less noise, simply because of the persistence of the phosphor.
I.e., the random peak-to-peak fluctuations don't occur with sufficient frequency to continually repaint on the screen... so you don't see them. What you do see are those parts of the signal that occur over and over again. Or in other words, the analog scope has built-in automatic averaging. Turn averaging on with your Rigol (or any DSO), and see how much cleaner things look! Almost analog-like. :) As little as 4x can make a big difference.
- Mark
rf-loop:
Mark_O
"...even with sin(x)/x reconstruction..."
My opinion is: Rigol have not this function at all. There is some kind of "smooth" function and nothing else.
Specially this can also see in my some pictures and... I understand they need do also this fake becouse BW is NOT compatible for real or near real Sin(x)/x.
Simon:
--- Quote from: Mark_O on March 18, 2010, 10:40:29 am ---
--- Quote from: Mark_O on March 18, 2010, 10:15:50 am ---Agilent did a paper on noise in digital scopes a while back, and it was quite illuminating. Even very expensive scopes can exhibit surprisingly high levels of relative noise, under some circumstances as much as 50% of one vertical division on a peak-to-peak basis! Turn on infinite Persistence, and things can get pretty ugly. ;)
--- End quote ---
They also did a nice job of dispelling the myth that digital scopes are intrinsically "noiser" than analog scopes. At first look, it seems obvious that the signals on a digital scope are much noiser, but that's attributable mostly to the difference in acquisition and display methods. I.e., the higher peak-to-peak noise levels you see on your digital scope are captured and displayed instantaneously. The exact same signal displayed on an analog scope will show much less noise, simply because of the persistence of the phosphor.
I.e., the random peak-to-peak fluctuations don't occur with sufficient frequency to continually repaint on the screen... so you don't see them. What you do see are those parts of the signal that occur over and over again. Or in other words, the analog scope has built-in automatic averaging. Turn averaging on with your Rigol (or any DSO), and see how much cleaner things look! Almost analog-like. :) As little as 4x can make a big difference.
- Mark
--- End quote ---
I beg to differ my rigol is noisy and the only way to cure it is use the inernal filtering and hope you don't have to measure in the same band as the noise
Mark_O:
--- Quote from: Simon on March 18, 2010, 12:39:24 pm ---I beg to differ my rigol is noisy and the only way to cure it is use the inernal filtering and hope you don't have to measure in the same band as the noise
--- End quote ---
So you're saying you've tried averaging, and it did no good?
- Mark
DJPhil:
For those of you looking for Dave, he's on walkabout for a while.
I'm sure when he gets back he'll do all his catching up and you'll hear from him. :)
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