Products > Test Equipment
REVIEW - Rigol DS2072 - First Impressions of the DS2000 series from Rigol
marmad:
--- Quote from: pa3bca on November 09, 2014, 05:31:00 pm ---Aha! Now it makes sense. From 100 -> 200 ms/div the display indeed changes from complete capture -> display to displaying "live" while capturing.
Thanks, this helped me a lot. (Still would like Rigol to do something about it, but it is probably not on top of a list)
--- End quote ---
It's definitely a quirky byproduct of their mathematics/display code, which could be changed with a little effort - although you could argue that it's actually displaying the intensity (after averaging) exactly correctly. It is curious to note though, that the intensity is, in fact, 'adjusted' by the DSO when stopped.
Try this: do a Single capture of a sine wave in High Res mode @ >=200ms/div with Intensity at 50%. You'll see the typical very dim waveform when the capture is done. Then just lightly turn (I don't mean PUSH - just very slightly rotate) the multifunction knob, and the intensity will snap back to an 'average' setting.
pa3bca:
--- Quote from: marmad on November 09, 2014, 05:45:15 pm ---Try this: do a Single capture of a sine wave in High Res mode @ >=200ms/div with Intensity at 50%. You'll see the typical very dim waveform when the capture is done. Then just lightly turn (I don't mean PUSH - just very slightly rotate) the multifunction knob, and the intensity will snap back to an 'average' setting.
--- End quote ---
Yes, I already noticed that (by twiddling the vertical position knob, even while capturing). That was (then) one of the reasons why I suspected a bug....
marmad:
--- Quote from: pa3bca on November 09, 2014, 05:48:02 pm ---Yes, I already noticed that (by twiddling the vertical position knob, even while capturing). That was (then) one of the reasons why I suspected a bug....
--- End quote ---
No, I think that Rigol's thinking is that the dimness is actually the mathematically correct intensity after averaging (as mentioned above) - so it's giving you the 'truest' image of the averaged + decimated samples. But once the DSO is stopped, the 'true' image of the incoming and processed samples is not as important as normal brightness.
At least, I can imagine that some engineer might have thought this way ;D
pa3bca:
--- Quote from: marmad on November 09, 2014, 05:54:16 pm ---
No, I think that Rigol's thinking is that the dimness is actually the mathematically correct intensity after averaging (as mentioned above) - so it's giving you the 'truest' image of the averaged + decimated samples. But once the DSO is stopped, the 'true' image of the incoming and processed samples is not as important as normal brightness.
At least, I can imagine that some engineer might have thought this way ;D
--- End quote ---
Ok so if the displayed trace(brightness) reflects the actual density/intensity of the original signal at that level, then increasing the amount of noise on the input should result in an even dimmer average trace (as the signal density per tracewidth would become smaller). Might try that later...
marmad:
--- Quote from: pa3bca on November 09, 2014, 06:26:53 pm ---Ok so if the displayed trace(brightness) reflects the actual density/intensity of the original signal at that level, then increasing the amount of noise on the input should result in an even dimmer average trace (as the signal density per tracewidth would become smaller). Might try that later...
--- End quote ---
No, the amount of noise won't make a difference: in High Res mode, it's already displaying the lowest intensity level possible.
Think of the math: for example, at 200ms/div in Normal mode (and the AUTO/14M memory setting), the sample rate is 5MSa/s, so the samples are every 200ns - and each column of the 400px waveform display area equals 7ms, so is derived from 35,000 samples. In other words, the intensity is roughly based on the number of hits between 0 to 35k (with 256 maximum divisions). If High Res is then turned on, the number of possible hits drops by a factor of 256 - which is already the lowest intensity level possible.
You can prove this by turning the intensity level to 0%, then running the DSO in High Res mode. It will always be a perfectly black trace.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version