Products > Test Equipment
REVIEW - Rigol DS2072 - First Impressions of the DS2000 series from Rigol
devitrify:
I think page 85 broke when I as posting a response to Marmad. I had trouble uploading a 1.5MB .BMP file, attached to my response, where the page (#85) would timeout when I posted. I tried 2 or three times, and succeeded with the post only after I removed my attachment. I then went back to modify the post to re-add the attachment, and that's when page 85 started behaving badly. My post exists, attached to my username devitrify, but it doesn't appear on page 85.
marmad:
--- Quote from: devitrify on June 13, 2013, 04:19:46 pm ---I think page 85 broke when I as posting a response to Marmad. I had trouble uploading a 1.5MB .BMP file, attached to my response, where the page (#85) would timeout when I posted. I tried 2 or three times, and succeeded with the post only after I removed my attachment. I then went back to modify the post to re-add the attachment, and that's when page 85 started behaving badly. My post exists, attached to my username devitrify, but it doesn't appear on page 85.
--- End quote ---
@devitrify: I just read your 'vanished' post (and your original post again). Obviously the Rigol, like all other low-cost DSOs, uses an 8-bit ADC, meaning that you would never get more than 256 discrete levels maximum. The Rigol does another trick (I'm not sure why, but I think partially for speed - and partially because of the 500uV/div setting) in which it only maps 200 (of the 256 possible) to the 400 pixel height of the display (25 levels = 50 pixels = 1 division ), effectively causing ~10% of the possible vertical resolution to fall offscreen, top and bottom. If you want to get as much vertical resolution as possible in your saved waveforms, you should adjust the display so the it overlaps the top and bottom by ~10% (one division).
Edit: If you download my software, RUU, it will display 10 divisions (if you check 'Full ADC') so that you can adjust the vertical scale precisely on the Rigol to match the (almost) maximum resolution (250 out of 256).
Here's an image saved of a full 10-division sine wave:
marmad:
@devitrify: BTW, one other point worth mentioning (which you may or may not be aware of): the DSO is doing sin(x)/x (or linear) interpolation for the display - constructing new data points within the range of the captured sample points; i.e. filling in-between the 'blanks'. It does not do this normally when you save the waveform - you only get the actual sample points, not the interpolated points - unless you save the display memory, as opposed to the sample memory.
tinhead:
--- Quote from: marmad on June 13, 2013, 04:32:58 pm ---The Rigol does another trick (I'm not sure why, but I think partially for speed - and partially because of the 500uV/div setting) in which it only maps 200 (of the 255 possible bits) to the 400 pixel height of the display, effectively causing ~10% of the possible vertical resolution to fall offscreen, top and bottom. If you want to get as much vertical resolution as possible in your saved waveforms, you should adjust the display so the it overlaps the top and bottom by ~10% (one division).
--- End quote ---
other manufacturers doing this as well, 10.24DIV for full scale, so each DIV represents 25 of 255 values.
Sure, they could use as well 8DIV each 32 of 255 values, but then the waveform would clip at the edge of the
screen, this didn't look good. It have as well something with display resolution vs amount of steps per DIV,
so yes, you right, it does speed up the calculation (display engine).
devitrify:
--- Quote from: marmad on June 13, 2013, 04:32:58 pm ---@devitrify: I just read your 'vanished' post (and your original post again). Obviously the Rigol, like all other low-cost DSOs, uses an 8-bit ADC, meaning that you would never get more than 256 discrete levels maximum.
--- End quote ---
Marmad, Rigol claims 12 bits of resolution for the DS2000 series in their posted specs at: http://www.rigolna.com/products/digital-oscilloscopes/ds2000/
but I understand you to say that these additional 4 bits are interpolated from the actual 8-bit measurement.
I am disappointed. I wish that manufacturers would simply state the resolution of their ADCs and separately indicate the means with which they achieve any additional resolution, much like optical vs digital zoom on cameras.
Marmad, I look forward trying out your RUU software. I've heard good things about RUU while exploring the info on these Rigol scopes.
Edited: OK, after posting above, I read the specs at Rigol more carefully...
From the specs:
Sample mode
High Resolution: 12 Bits of resolution when...
Vertical
Vertical Resolution: 8bit
I just don't know what "Sample Mode" means, and how it differs from the vertical resolution.
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