Products > Test Equipment
REVIEW - Rigol DS2072 - First Impressions of the DS2000 series from Rigol
edavid:
--- Quote from: WVL_KsZeN on April 18, 2014, 07:57:59 pm ---Here's a weird bug in the average function :
-hook up channel one to the 1khz test signal
-hit auto button
-change timebase to 50ms
now your signal just looks like a wide band, like you'd expect on a graded display. OK.
-turn on averaging in the acquire menu, 2x will do nicely.
-> wtf! what happened to our signal? the wide band just turned into a small ribbon
-it gets even weirder when turning on anti-aliasing, now the ribbon is waving over the screen
What is happening here? The scope is fetching 14Mpts, so there shouldnt be any weird aliasing things happening, but still it's there.
It looks normal again when you go to 20ms timebase.
--- End quote ---
Did you try setting the trigger to normal instead of auto?
miguelvp:
--- Quote from: edavid on April 18, 2014, 11:20:09 pm ---Did you try setting the trigger to normal instead of auto?
--- End quote ---
normal sweep has the same behavior.
Teneyes:
--- Quote from: WVL_KsZeN on April 18, 2014, 07:57:59 pm ---Here's a weird bug in the average function :
-turn on averaging in the acquire menu, 2x will do nicely.
--- End quote ---
Oh it's an Undocumented feature by Rigol. :)
I think some sort of Beat freq. with the way Averaging is calculated, combined with Intensity grading and Bug #18 noted in the 3rd post of this blog
Here's some more displays:
at slightly off frequencies (999.8, 999.9, 1000.05, 1000.1, 1000.2 Hz)
at off duty cycle 50.7%
and scanning at 49.80ms/div .
Note to Newbies: I used Marmad's RUU software to capture and post here in 30 sec/pix (no stick 4 me)
miguelvp:
--- Quote from: Teneyes on April 19, 2014, 02:24:47 am ---
Note to Newbies: I used Marmad's RUU software to capture and post here in 30 sec/pix (no stick 4 me)
--- End quote ---
Been meaning to install that software, specially for the cool plots in time. Thanks for the remainder (who am I kidding I probably wait another 4 months to do it).
WVL_KsZeN:
--- Quote from: Teneyes on April 19, 2014, 02:24:47 am ---
--- Quote from: WVL_KsZeN on April 18, 2014, 07:57:59 pm ---Here's a weird bug in the average function :
-turn on averaging in the acquire menu, 2x will do nicely.
--- End quote ---
Oh it's an Undocumented feature by Rigol. :)
I think some sort of Beat freq. with the way Averaging is calculated, combined with Intensity grading and Bug #18 noted in the 3rd post of this blog
Here's some more disppays:
at slightly off frequencies (999.8, 999.9, 1000.05, 1000.1, 1000.2 Hz)
at off duty cycle 50.7%
and scanning at 49.80ms/div .
Note to Newbies: I used Marmad's RUU software to capture and post here in 30 sec/pix (no stick 4 me)
--- End quote ---
What I don't get is that the signal is always completely messed up while triggering is functioning properly. You'd expect Rigol to do either of 2 things :
- calc average from screen data (but surely they can't, since you can still zoom in afterwards)
- calc running average from all the captured data (this is what they must be doing, since averaging also works when capturing 56Mptoints and there is simply no more memory)
But that last one is also not what is going on, we can see that. The signal is properly triggered, so the data should be the same for each captured waveform and at 50ms/division, we're getting about 50*12ms = 600ms of data, showing 600 periods of the 1kHz signal. So we have 14Mpts/600=23.333points available per period and should not expect any weird aliasing stuff..
Somehow Rigol must not be calculating the average from all the points from each waveform. It gives me the feeling that Rigol is using points from waveform 1 at time offset x and points from waveform 2 at time offset y to speed up the calculation. Or some other way to sneakily do it, giving these weird results.
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