Products > Test Equipment
REVIEW - Rigol DS2072 - First Impressions of the DS2000 series from Rigol
marmad:
--- Quote from: JDubU on December 17, 2013, 07:28:25 pm ---In regards to your previous post: Dots mode 100us --> 200us. The 200us setting does produce a display with unique dot artifacts at that one setting but, if I stop the sampling and zoom in, the sampling rate does match what is displayed at the top of the screen (by counting the dots per horizontal division).
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Thanks, JDubU! Yes, it appears as if it's a bug that's between sample memory and display memory - since the sample memory is correct when stopped. But there is something wrong in the routine which is building the intensity map in the display memory - thus screwing up the waveform update numbers as well. But it's causing errors at other time base settings as well - you can tell by switching to 1.4M sample depth and seeing what appears to be a higher sample rate (which should, in fact, be a lower sample rate).
I sent an email onto Drieg to report the bug to Rigol.
eV1Te:
--- Quote from: marmad on December 17, 2013, 06:59:47 pm ---Found a bug in the new firmware - incorrect setting of the sample rate in Dots mode at certain time bases (and maybe something else too).
Perhaps someone can confirm on their DSO? Also, if someone still has FW v.01.01.00.02 installed, could they please double-check to see if this bug is present in that FW or not?
To test:
Single channel on; Dot mode; test signal input (e.g. 1MHz sine) - the bug affects both AUTO/14M/56M memory settings (but not the others, I think).
Go from 100us/div to 200us/div - and watch the image change. The sample rate is clearly wrong; in the image it's supposed to be 2GSa/s:
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I don't see what is wrong? if you stop the scope and "zoom in" horizontally until you see the points, what is the distance? 0.5 ns?
I haven't seen Rigol actually specifying how many points the scope can show at once on the same screen, I guess it decimates the data in order to to get the 256 intensity gradings it is rated for.
For example the scope has 256 intensity gradings if i remember correctly and how many pixels wide is the graph part of the display? 700 pixels maybe?
256*700 dots = 179200 points at once on the screen. What is screen fps? 30? 179200 * 30 = 5376000 points on screen per second
You have 5.6 Mpoints memory which according to the table gives 88 Wfrm/s = 88*5600000 = 492800000 points captured per second
5376000/492800000 = 0.011 = ca. 1 % of the captured points are displayed on the screen.
marmad:
--- Quote from: eV1Te on December 17, 2013, 07:41:46 pm ---I don't see what is wrong?
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Here is the EXACT same signal and settings - except with 2 channels ON - and a 1GSa/s rate (LOWER than the first image). Can you see what's wrong now?
Bugware:
Same here with HW2 and old FW 00.01.01.00.02. (I could only test it with 16Mhz, but same at 200µs)
eV1Te:
--- Quote from: marmad on December 17, 2013, 07:48:36 pm ---
--- Quote from: eV1Te on December 17, 2013, 07:41:46 pm ---I don't see what is wrong?
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Here is the EXACT same signal and settings - except with 2 channels ON - and a 1GSa/s rate (LOWER than the first image). Can you see what's wrong now?
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I agree that it should look as good as that with one channel also, I just wanted to point out that when you have "too" many points in memory and an unfortunate frequency of the input signal you can get an apparent aliasing on the screen even though you have intensity graded display. But when the difference is that big it must be something else I would think as you pointed out.
What happens when you have anti-aliasing turned on in the first case, does it get better?
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